Acute appendicitis and peritonitis in children: clinical guidelines

List of Abbreviations

Terms and Definitions

Abdominal sepsis – a systemic inflammatory response of the body to a destructive process in the abdominal cavity and/or retroperitoneal space

Appendicular mass – a dense inflammatory conglomerate consisting of intestinal loops and greater omentum, forming in the abdominal cavity against the background of destructive inflammation of the appendix

"Appendicular mass" on ultrasound – a heterogeneous echo-structure of complex appearance with indistinct margins, in which a modified appendix, edematous intestinal loops, and edematous omentum may be visualized

Henoch-Schönlein purpura – a vasculitis primarily affecting small vessels

Instrumental diagnostics – diagnostics using various devices, apparatus, and instruments to examine a patient

Laboratory diagnostics – a set of methods aimed at analyzing test material using various specialized equipment

Laparoscopy – a modern minimally invasive surgical method in which operations on abdominal organs are performed through small incisions

Muscle defense (peritoneal sign) – passive, involuntary tension of the anterior abdominal wall muscles over the inflamed peritoneum

Intestinal paresis – impaired motility of the small intestine without a mechanical obstruction to the passage of intestinal contents

"Periappendiceal abscess 3" on ultrasound – an anechoic/hypoechoic formation (encapsulated fluid collection) of round or oval shape with clear margins (capsule); a modified appendix can sometimes be visualized in the wall area.

"Free fluid" on ultrasound – an anechoic collection in the pelvic cavity and other abdominal compartments detected on ultrasound

Kocher's sign – shifting of pain from the epigastric region to the right iliac fossa

Kümmell's sign – shifting of pain from the umbilical region to the right iliac fossa

Filatov's sign – tenderness upon palpation in the right iliac fossa in young children

Rovsing's sign – increased pain in the right iliac fossa upon deep palpation in the left iliac fossa

Щеткина-Блюмберга sign – increased pain upon sudden release of the hand after preliminary smooth pressure Образцов's sign (psoas sign) – increased pain during palpation in the right iliac fossa with the elevated right leg.

Sitkovskiy's sign – increased pain in the right iliac fossa when lying on the left side

Bartomier-Michelson's sign – increased tenderness upon palpation in the right iliac fossa when the patient lies on the left side

Voskresenskiy's sign (shirt sign) – sharp increase in pain in the right iliac fossa when the physician's fingertips slide over the patient's taut shirt from top to bottom

Pencil sign – the inflamed appendix is rigid and does not hang off the instrument during laparoscopic diagnostics

Intestinal failure syndrome – combined impairment of all gastrointestinal functions (motor, secretory, digestive, absorptive, and barrier), accompanied by endotoxemia

Sepsis – a pathological process based on the body's response in the form of generalized (systemic) inflammation to an infection of various origins (bacterial, viral, fungal), leading to acute organ dysfunction and failure

Septic shock – the most severe clinical course of sepsis, characterized by pronounced circulatory, cellular, and metabolic disturbances

Condition – changes in the body arising from the impact of pathogenic and/or physiological factors and requiring medical care

Syndrome – a set of symptoms sharing a common etiology and pathogenesis

Level of evidence – reflects the degree of certainty that the discovered effect of a medical intervention is true

Surgical intervention – an invasive procedure that can be used for diagnostic purposes and/or as a method of treating diseases

Surgical treatment – a method of treating diseases through the division and joining of tissues during a surgical operation

Kloiber's cups – a pathognomonic radiological sign of intestinal obstruction. Manifests as an "inverted cups" picture with horizontal fluid levels on an abdominal radiograph in the patient's upright position

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Acute appendicitis (AA) – acute non-specific inflammation of the cecal appendix.

Peritonitis – acute inflammation of the peritoneum accompanied by a complex of pathological processes occurring in the abdominal cavity and leading to a systemic inflammatory response, organ dysfunction, and sepsis.

Acute appendicitis is the primary cause of peritonitis in children. Peritonitis typically develops due to perforation of the appendix resulting from destruction of its wall (gangrenous-perforative appendicitis), but it can also develop without wall perforation in phlegmonous and gangrenous appendicitis.

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

The etiopathogenesis of acute appendicitis was actively studied throughout the 19th and 20th centuries [1]. However, to date, there is no consensus on the cause of acute appendicitis. Appendix inflammation is a non-specific infectious-inflammatory process. Opportunistic intestinal flora (Enterobacteriaceae, Bacteroides, etc.) plays a significant role in the development of the inflammatory process, becoming the primary pathogen in the development of peritonitis in the event of appendiceal perforation. The dominant pathogens in appendicular peritonitis are Escherichia coli, Bacteroides spp., Peptostreptococcus, and Pseudomonas [2-11].

The main etiopathogenetic factors in the development of inflammation in the vermiform appendix include impaired passage of contents, microcirculatory disturbances in the appendiceal wall, and the formation of a "primary affect"—a primary focus of inflammation in the form of a wedge-shaped defect of the appendiceal mucosa, as well as alterations in the immunological reactivity of the child's body [1, 3–11].

The mechanical theory (theory of stasis, closed cavities) was proposed in 1896 by Paul Georges Dieulafoy. As a result of obstruction of the vermiform appendix by a fecalith, a foreign body, or kinking due to adhesions, the outflow of secreted mucus is disrupted, leading to increased pressure in its lumen and the development of inflammation. In 1905, the German pathologist Ludwig Aschoff put forward the infectious theory. Aschoff suggested that fecal stasis in the appendix leads to the activation of virulent bacterial strains (most commonly gram-positive diplococci) and the formation of a primary affect. In the 1930s, Gustav Ricker proposed the angioneurotic theory, where the main pathogenetic factor of inflammation is microcirculatory disturbance in the wall of the vermiform appendix due to impaired neural regulation. Also in the 20th century, the immunological theory of inflammation developed, associated with the disruption of immune homeostasis and the triggering of an inflammatory cytokine cascade in the appendiceal mucosa.

Despite the fact that none of these theories has been confirmed as fully independent, most modern researchers recognize the factors presented in them as fundamental in the development of inflammation in the vermiform appendix [1, 3–11].

1.3 Epidemiology of the Disease or Condition

Acute appendicitis can occur at any age, including neonates, but is predominantly observed after 7 years of age; in children under 3 years, its frequency does not exceed 8% [3]. The peak incidence occurs between 9 and 12 years of age [3]. The overall incidence of appendicitis ranges from 3 to 6 per 1,000 children [3]. According to the largest epidemiological study of appendicitis in recent years (Anderson et al., 2012), the incidence of appendicitis was highest among Caucasians and Hispanics and lower among African Americans and Asians [12]. It is known that the incidence of appendicitis varies seasonally, with a peak in the summer months in the Northern Hemisphere from May to July, decreasing by February [12]. Girls and boys are affected with equal frequency. In infants and young children, appendicitis develops more rapidly, and destructive changes in the appendix leading to appendiceal peritonitis occur significantly more often than in adults [3-9].

Epidemiological studies of appendicitis in children are limited and consistently report a decreasing trend in incidence. However, most of these studies were conducted in Western countries and are based on data from the past century [13]. According to Ran He et al. (2025), in 2021 acute appendicitis was diagnosed in 2,193,020 children, accounting for 12.93% of all appendicitis cases in the general population. The corresponding incidence rate was estimated at 109 per 100,000. From 1990 to 2021, the incidence of appendicitis in children increased by 0.3% per year. In 2021, the incidence of appendicitis in children increased with age, with children aged 10 to 14 years being most frequently affected. The incidence varies widely across different regions and countries [13].

1.4 Features of Coding the Disease or Condition

K35 – Acute appendicitis

K35.2 – Acute appendicitis with generalized (diffuse) peritonitis following rupture or perforation

K35.3 – Acute appendicitis with localized peritonitis with or without perforation (peritoneal abscess)

K35.8 – Acute appendicitis, other or unspecified, without mention of localized or generalized peritonitis

K36 – Other forms of appendicitis

K37 – Unspecified appendicitis

K38.1 – Appendicular calculi

K38.8 – Other specified diseases of appendix

K65 – Peritonitis

K66.8 – Other specified disorders of peritoneum

1.5 Classification of the disease or condition

Acute appendicitis is traditionally classified according to morphological changes in the vermiform appendix [1, 3–21]. Preoperative diagnosis of the form of inflammation of the vermiform appendix is extremely difficult. Intraoperative diagnosis based on macroscopic appearance also does not exclude subjectivity [14]. Morphological changes in the appendix are patchy, and their precise diagnosis is only possible through histological examination. For the surgeon, it is most important to distinguish between non-destructive and destructive appendicitis, since the presence of tissue destruction due to appendiceal inflammation determines the surgical treatment strategy generally accepted in Russia. Non-destructive appendicitis presents a particular challenge for the surgeon, as this form typically masks other diseases that simulate acute appendicitis. The stages of inflammatory development include catarrhal appendicitis. However, when performing an appendectomy for non-destructive appendicitis, the surgeon generally encounters not the catarrhal stage of inflammation—which likely lacks clear clinical, sonographic, and macroscopic manifestations—but secondary changes in the vermiform appendix (lymphoid hyperplasia, periappendicitis), which requires a correct histological conclusion. In the postoperative diagnosis, prior to obtaining the histological report, it is advisable to use the term "acute appendicitis" when removing a vermiform appendix with questionable changes, and "secondary appendicitis" when diagnosing the primary cause of pain syndrome during laparoscopy.

Destructive appendicitis is traditionally divided into phlegmonous and gangrenous forms according to the morphological picture. In addition, a distinction is made between uncomplicated and complicated appendicitis (appendiceal infiltrate, periappendicular abscess, peritonitis) [3, 4, 7–18, 21].

Classification of acute appendicitis:

• Non-destructive (simple) (K35 Acute appendicitis);

• Destructive (K35.8 Acute appendicitis, other or unspecified, without mention of localized or generalized peritonitis):

  • Phlegmonous;

  • Gangrenous;

Complications:

• Perforation;

• Infiltrate;

• Abscess;

• Peritonitis

• Pylephlebitis;

• Retroperitoneal phlegmon.

Complicated appendicitis is understood as forms of acute appendicitis with the spread of the inflammatory process from the vermiform appendix to the abdominal cavity, which can occur either as a result of appendiceal perforation (gangrenous-perforative appendicitis) or without perforation. From the perspective of general pathology, all these forms are variants of peritonitis (inflammation of the peritoneum).

Complicated appendicitis:

• Appendicular infiltrate

  (K37 Unspecified acute appendicitis);

• Appendicular (periappendicular) abscess, stages 1, 2, 3

  (K35.33 Acute appendicitis with peritoneal abscess);

• Appendicular peritonitis

  (K35.2 Acute appendicitis with generalized (diffuse) peritonitis following rupture or perforation).

Classifications of complicated appendicitis in Russia include a large number of terms, including synonyms (localized, delimited, local, locally delimited, locally undelimited, widespread, diffuse, generalized, etc.), which causes confusion and complicates the evaluation of treatment outcomes. However, established clinical practice does not allow for the adoption of a unified terminology today. Under these conditions, it is advisable to distinguish three main forms of complicated appendicitis: infiltrate, abscess, and peritonitis. From the perspective of disease classification, the form and extent of the inflammatory process in the abdominal cavity (infiltrate, abscess, free purulent effusion, and combinations thereof) determine the therapeutic strategy and surgical tactics.

Appendicular infiltrate (AI) is a dense inflammatory conglomerate consisting of intestinal loops and the greater omentum, formed in the abdominal cavity against the background of destructive inflammation of the vermiform appendix. Appendicular infiltrate is detected on palpation through the anterior abdominal wall and is clearly visualized on ultrasound. When laparoscopy is performed in doubtful cases, the abdominal cavity reveals a mass of inflamed, edematous intestinal loops and omentum that are intimately fused together; separating them presents significant technical difficulties and a risk of hollow organ injury. It is inappropriate to subdivide AI into loose and dense, or hot and cold. This is because neither a "loose infiltrate," which represents an adhesive infiltrative-adhesive process around the appendix, nor a "hot" or abscess-forming infiltrate, which represents an abscess, reflects the definition of an infiltrate. In the absence of a dense mass palpable through the anterior abdominal wall, it is incorrect to call the process an infiltrate, and in the presence of localized purulent exudate, the inflammatory process has the exhaustive designation of an abscess. In cases of appendicular infiltrate, conservative treatment followed by interval appendectomy is successfully performed, which dictates the classification of this form of inflammation as an independent entity among complicated forms. When a loose infiltrative-adhesive process around the appendix is discovered during laparoscopy, laparoscopic appendectomy is performed without technical difficulties. The clinical, laboratory, and sonographic presentation, surgical technique, and postoperative management in these cases do not differ from those of destructive appendicitis.

Periappendicular abscess (PA). The stages of PA in pediatric surgery were first proposed by S.Ya. Doletsky et al. [15]. The use of videolaparoscopic techniques has made it possible to detail the nature and staging of pathological changes in the abdominal cavity during the formation of a periappendicular abscess. From the endosurgeon's perspective, the main criterion for subdividing PA into stages is the possibility of minimally invasive endoscopic destruction of existing demarcations, followed by effective debridement of the abscess cavity. In the early stages of the disease, the organs and tissues forming the walls of the abscess (PA 1, 2) are involved in a loose infiltrative-adhesive process and, despite existing inflammatory changes, are well differentiated, which ensures the possibility of safe endoscopic destruction of the abscess. With a long duration of the disease (more than 5 days), pronounced inflammatory edema and infiltration of the organs and tissues forming the abscess walls (PA 3), as well as the formation of a granulation capsule, determine their rigidity and make it possible to diagnose the pathological formation in the abdominal cavity before surgery on the one hand, while on the other hand, they reliably limit the spread of the infection process to the free abdominal cavity and dictate the tactics of an extraperitoneal approach for opening and drainage. Thus, it is advisable to subdivide PA into 3 stages depending on the severity of the infiltrative-adhesive process in the organs and tissues forming its walls, which at the present stage determines the surgical tactics and the feasibility of laparoscopic operations for PA 1, 2 [15, 16, 17, 18].

PA 1 – infiltrative changes in the tissues and organs forming the abscess walls are mildly pronounced; localization of purulent exudate (5–7 ml) in the region of the appendix occurs due to an adhesive process, without capsule formation. PA 1 is generally diagnosed intraoperatively; the adhesions are easily and completely disrupted, pus is aspirated, and the appendix is removed without technical difficulties.

PA 2 – localization of purulent effusion (up to 20 ml) in the region of the appendix occurs due to a loose adhesion process without the formation of an abscess capsule. Infiltrative changes in the tissues and organs forming the walls are moderately pronounced, and the latter are well differentiated, which determines the possibility of their minimally invasive intraoperative destruction with targeted debridement of the purulent exudate. After destruction, infiltrative tissue changes persist in the area of the destroyed abscess. PA 2 is also diagnosed intraoperatively, although in some cases preoperative diagnosis of PA 2 by ultrasound is possible in the form of a small, irregularly shaped fluid collection in the appendix region without a capsule. The sonographic picture is not pathognomonic for an abscess and may occur in uncomplicated appendicitis.

The duration of the disease and clinical presentation in PA 1 and 2 do not differ from the characteristics of uncomplicated appendicitis.

PA 3 – localization of purulent effusion in the region of the appendix occurs due to a pronounced infiltrative-adhesive process with the formation of a granulation capsule. The duration of the disease in PA 3 is typically 5–7 days or more; the abscess has a round or oval shape, a capsule, and a volume of more than 20 ml. PA 3 has pathognomonic ultrasound characteristics.

Appendicular peritonitis (AP). From the perspective of acute appendicitis classification as a separate nosology, appendicular peritonitis should be understood as the presence in the abdominal cavity of free purulent exudate or its transitional forms (seropurulent, fibrinosurulent). Understanding peritonitis as inflammation of the peritoneum in the broad sense of the word is valid from the standpoint of general pathology [19, 20], but does not meet the needs of clinicians. It allows the comparison of treatment results for conditions that are incomparable in the severity of their clinical manifestations and organ dysfunctions. It is well known that uncomplicated destructive appendicitis features hyperemia of the peritoneum adjacent to the appendix and a small amount of reactive serous effusion, not only in the appendix area but also in the pelvic cavity. Nevertheless, these changes do not alter the clinical picture and course of the disease characteristic of uncomplicated appendicitis and cannot be interpreted as peritonitis.

In practical work, additional utilization of AP systematization depending on the prevalence and form of the inflammatory process is possible in accordance with the scientific school's terminology of the clinic and the local protocol. The spread of the inflammatory process to more than 3 anatomical regions is typically accompanied by an increase in intoxication syndrome, often with the development of abdominal sepsis [17]. Involvement of all compartments of the abdominal cavity in the inflammatory process with the formation of loculated abscesses is accompanied by the development of intra-abdominal hypertension syndrome (IAHS) and abdominal sepsis, which requires maximum intensive care and special surgical techniques [16, 17, 21–22].

Appendicular peritonitis prevails in the structure of peritonitis in children, accounting for more than 90% in children older than the neonatal period. The main cause of peritonitis in neonates is necrotizing enterocolitis (NEC). In preschool children, primary peritonitis due to hematogenous spread of infection in frequently ill children also occurs and requires differential diagnosis with acute appendicitis. Secondary peritonitis due to perforation of a hollow organ (stomach, intestine, gallbladder, etc.) as a result of inflammatory-destructive processes or trauma, including inflammation and trauma of the pancreas, can occur at any age. The clinical picture of peritonitis requires differential diagnosis and clarification of the cause of its development.

Classification of peritonitis by etiology:

• primary (hematogenous or lymphogenous);

• secondary (presence of an infection focus in the abdominal cavity);

• tertiary (due to multiple organ dysfunction syndrome [MODS], sepsis);

By prevalence:

• localized (one anatomical region);

• diffuse/generalized (multiple abdominal regions);

By the nature of the exudate:

• serous;

• serofibrinous;

• fibrinosurulent;

• purulent;

• biliary;

• pancreatogenic;

• fecal;

• urinary.

Complications:

systemic:

• sepsis;

• septic shock;

• multiple organ failure;

abdominal:

• intra-abdominal hypertension syndrome (IAHS);

• intestinal failure syndrome (IFS);

• adhesive intestinal obstruction (early, late);

• abdominal infiltrate;

• abdominal abscess.

1.6 Clinical presentation of the disease or condition

The typical picture of acute appendicitis is characteristic of children over 5 years of age with a typical location of the vermiform appendix in the right iliac region [3–11, 23–29]. The typical location of the vermiform appendix is generally considered to be in the right iliac region, such that the appendix, regardless of its direction, is in contact with the parietal peritoneum of the anterior abdominal wall, which upon the development of inflammation leads to local symptoms. Atypical locations of the appendix include subhepatic, in the lateral gutter, pelvic, retrocecal, subileal, and on the left side of the abdomen.

The disease begins suddenly against a background of complete health. The main complaints are abdominal pain, nausea, and vomiting. Patients usually complain of abdominal pain without clear localization (in the epigastric or periumbilical regions), with or without anorexia, nausea, and vomiting. Vomiting is generally single-episode and typically occurs in the first hours of the disease. Within a few hours, the pain shifts from the epigastric (Kocher's sign) or periumbilical (Kümmell's sign) region to the right iliac fossa, may be accompanied by a rise in body temperature to subfebrile levels, and muscle guarding and positive signs of peritoneal irritation appear. The pain is usually constant and aching in nature. A number of children experience constipation or diarrhea. High fever is not typical for uncomplicated forms of acute appendicitis. A characteristic sign is tachycardia that does not correspond to the grade of fever.

When the appendix is in an atypical location, the localization of pain corresponds to the position of the appendix (in the right hypochondrium, hypogastrium, etc.). With retrocecal, subileal, and pelvic locations of the appendix, muscle guarding and Shchetkin-Blumberg's sign are absent because the appendix does not come into contact with the parietal peritoneum of the anterior abdominal wall. With a pelvic location of the appendix, frequent painful urination as well as frequent loose stools may be observed.

In newborns, inflammation of the appendix develops extremely rarely and is usually diagnosed upon the development of peritonitis. The use of modern imaging modalities, primarily ultrasound, makes it possible to establish the diagnosis of acute appendicitis in newborns before complications develop. The clinical picture of acute appendicitis in children under 3 years of age most often develops rapidly and manifests with non-specific symptoms of acute abdominal syndrome [3-9, 24]. Against a background of complete health, the child becomes restless, irritable, refuses to eat, body temperature rises to 38-39 °C, and repeated vomiting occurs.

There is no direct correlation between the intensity of pain and the degree of morphological changes in the appendiceal wall. In gangrenous appendicitis, the initial severe abdominal pain may subside to the point of complete absence. A sudden sharp increase in pain is observed upon perforation of the appendix. Clear localization of the pain is lost and the area of its radiation increases with the development of peritonitis.

Thus, the main clinical symptoms of acute appendicitis with its typical location are local symptoms detected by abdominal palpation in the right iliac fossa (right lower quadrant):

• Local tenderness upon palpation (Filatov's sign in younger children);

• Muscle guarding;

• Shchetkin-Blumberg sign.

A large number of symptoms of acute appendicitis bearing the names of authors (Shchetkin-Blumberg, Voskresensky, Razdolsky, Rovsing, Sitkovsky, Bartomier-Michelson, Obraztsov, etc.) are described in the literature. All of them are a consequence of irritation of the parietal peritoneum in the area where the appendix is located. In clinical practice in pediatric surgery, the Shchetkin-Blumberg sign is the most widely used. One should remember Obraztsov's sign, which occurs when the appendix has a retrocecal location.

2. Diagnostics, medical indications and contraindications for diagnostic methods

Diagnosis of acute appendicitis is based on interview data (complaints and anamnesis), results of physical, laboratory, and instrumental examinations. In the majority of patients, the diagnosis of acute appendicitis does not cause major difficulties. However, in some patients, recognizing the disease can be extremely difficult. Acute appendicitis can mimic many conditions accompanied by abdominal syndrome [1, 3–11, 23-30]. Most often, acute appendicitis in children must be differentiated from the following conditions:

• acute viral infections with abdominal syndrome;

• coprostasis;

• nonspecific mesadenitis;

• intestinal infections;

• pneumonia, especially right-sided;

• urinary tract infection, renal colic;

• acute pelvic inflammatory diseases in girls;

• acute testicular diseases in boys;

• Meckel's diverticulitis;

• gastric and duodenal ulcers;

• acute cholecystitis;

• acute pancreatitis;

• intussusception;

• intestinal obstruction;

• Crohn's disease;

• hemorrhagic vasculitis (Henoch-Schönlein purpura).

It should also be remembered that diabetes mellitus, Burkitt lymphoma [23, 30], inflammatory bowel disease, and other rare diseases can mask acute appendicitis.

To improve the diagnosis of acute appendicitis, diagnostic scoring systems for clinical decision-making have been proposed. However, none of them has found widespread use in Russia. Appendix G presents the 3 scales most widely used in global practice: the Appendicitis Inflammatory Response score (AIR), PAS, and the Alvarado scale [25-27]. The use of scoring systems improves the preoperative diagnosis of acute appendicitis, especially when ultrasound is unavailable [25-27].

Diagnostic criteria:

1. anamnestic data indicating the nature and time of onset of disease symptoms (see section 1.6);

2. physical examination data characteristic of acute appendicitis (see section 1.6);

3. laboratory examination data;

4. instrumental examination data.

Comments: The first examination of the patient in the surgical department by a pediatric surgeon must be performed no later than 2 hours after hospitalization with a record in the medical history. Based on the results of the examination, taking into account the performed laboratory and instrumental examination, the diagnosis of acute appendicitis must be established and indications for surgical treatment determined, or dynamic observation continued in case of a doubtful diagnosis of acute appendicitis.

Comments: In the absence of convincing signs of acute appendicitis (local tenderness in the right iliac fossa in the absence of muscle guarding and signs of peritoneal irritation) and doubtful or negative ultrasound data, dynamic observation is carried out for 12 hours with repeated examinations of the child by a pediatric surgeon and a record in the medical history no later than after 6 hours of observation. If doubts about the diagnosis persist, diagnostic laparoscopy is indicated.

According to a 2018 systematic review, an appendectomy performed within the first 24 hours after hospitalization is not associated with an increased risk of appendiceal perforation or adverse outcomes [32]. WSES considers that appendectomy should be performed within the first 24 hours after hospitalization [21].

2.1 Complaints and Anamnesis

Comments: The localization of abdominal pain depends on the location of the appendix and the development of complications. The possibility of an atypical location of the appendix, including left-sided, should be kept in mind. Pain in the right iliac fossa can also be caused by other conditions, including acute testicular diseases in boys.

Comments: When interviewing the patient and/or their parents, one may find that prior to the onset of the leading symptom (abdominal pain), certain changes in the child's behavior were noted—lethargy, fatigue, decreased appetite. Dysuric phenomena may be a sign of pelvic localization of the appendix, as well as diarrhea or tenesmus. In middle and high school-aged girls, a gynecological history must be taken (age at menarche, menstrual cycle characteristics), and in boys, complaints of pain in the inguinoscrotal region should be clarified to rule out scrotal pathology. With a retrocecal location of the appendix, pain may be localized in the right lumbar region with radiation to the right leg. A detailed characterization of symptoms allows for the differential diagnosis of abdominal pain syndrome.

2.2 Physical Examination

Comments: The examination must be performed while undressed, which allows for assessing the condition of the skin and ruling out a rash. When examining boys, it is mandatory to inspect the external genitalia to rule out acute scrotal conditions and incarcerated inguinal-scrotal hernia. The possibility of Amyand's hernia (location of the vermiform appendix within the hernia sac in an inguinal-scrotal hernia) should also be kept in mind. In uncomplicated acute appendicitis, the child's general condition is mildly affected. However, attention is drawn to the child's gait (slightly stooped, cautious, as if protecting the abdomen) and forced position in bed (the child lies on the right side with knees bent). With the development of appendicular peritonitis, the child's condition can be severe to critical. In appendicular infiltrate and periappendiceal abscess, the child's condition remains stable, but intoxication symptoms and fever are usually present. In uncomplicated appendicitis, the abdomen has a normal shape and participates in the act of breathing. In appendicular peritonitis, the abdomen may be distended and lag behind in the act of breathing.

Comments: Abdominal palpation begins with the patient in a supine position: superficially from the left iliac region, gradually moving toward the right. Palpation of the abdomen may reveal localized tenderness, muscular defense, and Shchetkin-Blumer's sign in the right iliac region. With a retrocecal position of the vermiform appendix, Obraztsov's sign (psoas sign) may be elicited. In appendicular infiltrate and periappendiceal abscess in the right half of the abdomen, a dense, painful pathological mass can sometimes be palpated, but most frequently the above-mentioned triad of symptoms (pain on palpation, muscular defense, Shchetkin-Blumberg sign) is determined over the infiltrate/abscess. In appendicular peritonitis, abdominal tenderness is more pronounced, and muscular defense and peritoneal irritation signs are also detected in other abdominal regions depending on the spread of the inflammatory process. Examining younger children during dynamic observation is advisable to perform during physiological sleep. In case of marked agitation and negative reaction of the child to the examination, it can be performed during drug-induced sleep.

Comments: Pulmonary auscultation helps rule out pulmonary pathology (pneumonia), which can mimic "acute appendicitis" or be a complication of appendicular peritonitis with the development of abdominal sepsis.

Comments: Abdominal auscultation allows for determining the characteristics of intestinal peristalsis, including the presence of pathological bowel sounds.

Comments: Digital rectal examination (per rectum) (transrectal digital examination) allows for detecting pain and doughy consistency of the bowel vault on the right in pelvic positions of the vermiform appendix, which may clinically manifest as dysuria and frequent stools. The examination is most informative in the presence of a pelvic mass (abscess, infiltrate, ovarian cyst, hematometra). For a long time, this procedure was a mandatory component of the diagnostic workup for suspected acute appendicitis in our country. In recent years, with the introduction of ultrasound into clinical practice for diagnosing acute appendicitis, the value of the per rectum examination has significantly decreased. When the clinical picture of acute appendicitis is clear, as well as when ultrasound is available, the examination is unnecessary and, among other things, can cause psychological trauma to the child. The examination should not be considered routine and may be used in complex diagnostic cases (pelvic appendix location, gynecological pathology, pelvic abscess/infiltrate). Legal aspects of the issue must be kept in mind. The examination must be performed after appropriate explanations and informed consent from the patient/patient's legal representatives.

2.3 Laboratory Diagnostics

For suspected acute appendicitis, a standard laboratory workup for abdominal syndrome should be performed.

Comments: An elevated leukocyte count with a left shift is a sign of an inflammatory process in the vermiform appendix with the development of destructive changes. However, both uncomplicated and complicated appendicitis may present with a normal leukocyte count. On the other hand, leukocytosis is a characteristic of most diseases included in the differential diagnosis of abdominal syndrome. A decrease in hemoglobin and erythrocyte levels may indicate pre-existing anemia in the child. Elevated hematocrit, hemoglobin, and erythrocyte counts may indicate hypovolemia in the setting of pronounced intoxication.

Comments: Urinalysis allows for differential diagnosis within abdominal pain syndrome and helps rule out urinary tract pathology.

Comments: A severe condition is usually due to complicated forms of acute appendicitis, but can also occur in uncomplicated forms in young children, as well as in other diseases requiring differential diagnosis with acute appendicitis. Identified signs of hypovolemia and metabolic disorders require immediate correction.

Comments: The general clinical blood biochemistry panel allows for assessing blood protein pools and organ failure. Blood glucose is a key criterion in diagnosing the onset of diabetes mellitus, which often manifests as abdominal syndrome against the background of ketoacidosis development. A severe condition typically develops in complicated appendicitis, and may occur in young children with uncomplicated appendicitis, as well as in other diseases with abdominal syndrome requiring differential diagnosis with acute appendicitis.

Comments: The C-reactive protein (CRP) level is a marker of the severity of the infectious process. CRP levels are used in the scoring system of the AIR (Appendicitis Inflammatory Response) score.

Comments: A coagulogram is an analysis aimed at assessing the blood coagulation system. The coagulogram includes tests for APTT, fibrinogen, INR, and Antithrombin III. Assessing APTT, fibrinogen, and INR levels helps diagnose the development of hypocoagulation and DIC syndrome in complicated appendicitis, as well as perform differential diagnosis within abdominal syndrome.

Comments: Depending on the capabilities of the microbiological laboratory, various methods are used: disk diffusion method for antimicrobial susceptibility testing; gradient diffusion method for antimicrobial susceptibility testing; dilution methods for antimicrobial susceptibility testing; automated analyzers for antimicrobial susceptibility testing; and breakpoint methods for antimicrobial susceptibility testing. To obtain a rapid response, it is also advisable to perform rapid testing of antimicrobial susceptibility to endotoxins in purulent discharge or rapid testing of antimicrobial susceptibility to endotoxins in exudate.

Comments: In a complicated postoperative course, microbiological monitoring (blood cultures, throat and anal swabs) is performed to determine the leading pathogen and the flora colonizing the patient's mucous membranes. During treatment, in the event of ongoing peritonitis or sepsis, the leading pathogens obtained intraoperatively from the peritoneal fluid may be replaced by hospital-acquired flora. Microbiological monitoring in this situation allows for targeted changes in antibacterial therapy, taking into account susceptibility to the most likely pathogens colonizing the patient's mucous membranes. Depending on the capabilities of the microbiological laboratory, various methods are used: disk diffusion method for antimicrobial susceptibility testing; gradient diffusion method for antimicrobial susceptibility testing; dilution methods for antimicrobial susceptibility testing; automated analyzers for antimicrobial susceptibility testing; and breakpoint methods for antimicrobial susceptibility testing. To obtain a rapid response, it is also advisable to perform rapid testing of antimicrobial susceptibility to endotoxins in purulent discharge or rapid testing of antimicrobial susceptibility to endotoxins in exudate.

2.4 Instrumental Diagnostics

High diagnostic accuracy, lack of ionizing radiation, and patient comfort make ultrasound the preferred imaging modality for diagnosing acute appendicitis.

Comments: Ultrasound makes it possible to visualize the appendix, which during inflammation appears as a non-peristaltic tubular structure with a diameter of more than 6 mm, thickened (2–3 mm) hypoechoic walls, and a lumen that may be filled with heterogeneous fluid contents (empyema of the appendix) or a fecalith. A small fluid collection and/or edematous omentum may be visualized around the appendix.

In complicated appendicitis, in addition to visualizing the appendix itself, ultrasound can diagnose free fluid in the abdominal cavity, intra-abdominal abscesses including periappendicular abscess grade 3 and infiltrates, inflammatory changes in internal abdominal organs (edema of the gallbladder wall, edema of the small and/or large intestine wall), and intestinal failure syndrome (IFS). An echographic picture pathognomonic for an abscess occurs only in the presence of a formed abscess of significant volume in the abdominal cavity (periappendicular abscess grade 3). Periappendicular abscesses (PA) grades 1 and 2 do not have a specific echographic picture and are visualized as a small fluid collection near the altered appendix.

Intestinal failure syndrome: IFS grade 1 – uneven increase in the diameter of intestinal loops up to 20–25 mm in the right iliac and adjacent anatomical regions; IFS grade 2 – intestinal loops up to 30–35 mm in diameter with thickened walls, filled with liquid contents, are visualized in all abdominal regions; chyme movement is pendular; IFS grade 3 – intestinal loops greater than 35 mm in diameter with thickened walls, filled with liquid contents, are visualized in all abdominal regions; peristalsis and chyme movement are absent, abdominal visualization may be difficult due to gas accumulation in the intestinal loops [17].

Given its non-invasiveness and lack of radiation exposure, ultrasound is advisable to use as the first-line imaging modality in the diagnosis of acute appendicitis in children [3, 11, 21, 35–41].

Comments: SCT is an effective imaging tool for many abdominal diseases. The main drawback of SCT is radiation exposure. At the same time, studies by foreign authors have proven that routine use of SCT reduces the number of negative appendectomies and increases the detection rate of abdominal diseases [36–41]. In Russia, SCT has not become widespread in routine practice. In the updated 2020 WSES guidelines for the diagnosis and management of acute appendicitis, SCT is not considered a first-line imaging modality in children with right lower quadrant pain [21]. In most cases, if ultrasound is available, there is no need to perform SCT. SCT is advisable in complex diagnostic cases when ultrasound results are ambiguous, as well as when mass lesions are detected on ultrasound.

MRI can also be used in complex diagnostic cases for the differential diagnosis of abdominal mass lesions. According to a review published in 2025, MRI is highly accurate in confirming and excluding acute appendicitis in adults and children regardless of the protocol [42, 43].

Although SCT and MRI have high diagnostic value for acute appendicitis, they are not first-line diagnostic methods. However, these methods should be used in complex diagnostic cases, including the diagnosis of abdominal space-occupying lesions. If the patient is in a stable condition and the required equipment is unavailable at the hospital, the patient must be referred to a higher-level medical facility.

Comments: Plain abdominal radiography has no diagnostic value for diagnosing acute appendicitis. However, it can be useful for differential diagnosis to rule out free air in the abdominal cavity caused by hollow viscus perforation (perforated gastric and duodenal ulcer, abdominal trauma with hollow viscus injury). In addition, signs of small bowel obstruction can be diagnosed: horizontal fluid levels in the small intestine (Kloiber's cups) and the absence of gas in the large intestine, as well as radiopaque foreign bodies, including magnetic ones.

Comments: Diagnostic laparoscopy became widespread in Russia in the 1980s and revolutionized the diagnosis of acute appendicitis, replacing diagnostic laparotomy with a minimally invasive and highly informative intervention that spares the patient from an unnecessary appendectomy. The introduction of diagnostic laparoscopy into pediatric surgery practice led to a reduction in negative appendectomies, which previously accounted for up to 25–30% and were interpreted as catarrhal or simple appendicitis [44–46]. The use of diagnostic laparoscopy made it possible to prove that "catarrhal appendicitis" is actually secondary reactive changes in the surface tissues or lymphoid apparatus of the vermiform appendix occurring against the background of other inflammatory diseases of the abdominal cavity (nonspecific mesadenitis, primary peritonitis, pelvioperitonitis, intussusception, Meckel's diverticulum, gynecological pathology, etc.) and does not require an appendectomy, since the destructive changes in the vermiform appendix characteristic of acute appendicitis as a distinct nosology are absent. Currently, with the widespread introduction of ultrasound into practice, the role of diagnostic laparoscopy has significantly decreased. However, it should be noted that even when a clinic fully transitions to laparoscopic surgery, diagnostic laparoscopy remains an important stage of the surgical intervention. If destructive appendicitis is detected, laparoscopic appendectomy is indicated provided the specialist and equipment are available, or conversion to open appendectomy should be performed. In the absence of destructive changes in the vermiform appendix, appendectomy is not indicated.

To determine the indications for appendectomy, surgeons rely on the macroscopic signs of AA: increased diameter of the vermiform appendix and its infiltration (rigidity), dullness of the serosa and color change (hyperemia, purple or gray-black color), presence of fibrin deposits, and presence of perforation. A manifestation of appendiceal empyema (pus-filled sac) is its flask-like enlargement and tension with minimal serosal changes. In doubtful inflammatory changes of the vermiform appendix (injection of blood vessels in the serous layer), the key method for determining destructive changes during diagnostic laparoscopy is its instrumental palpation and "hanging" on an instrument to determine rigidity (the "pencil sign"). If the vermiform appendix does not hang freely over the instrument—the "pencil sign" is positive—this must be regarded as destructive appendicitis, and an appendectomy should be performed. If it hangs freely over the instrument—the "pencil sign" is negative—this must be regarded as secondary appendicitis, i.e., a manifestation of another abdominal pathology. In this case, further exploration of the abdominal organs should be performed (80–100 cm of the ileum, small pelvis, mesenteric lymph nodes of the small intestine). In secondary appendicitis, appendectomy is not indicated. Performing a "concomitant" appendectomy can lead to postoperative complications and seriously hinder the identification of the true cause of the abdominal syndrome. If indications for appendectomy are identified during diagnostic laparoscopy, performing the surgery via a laparoscopic approach is preferred.

Comments: Following surgical treatment of uncomplicated appendicitis, ultrasound is performed before the patient's discharge (postoperative days 3–5). In the postoperative period after surgical treatment of complicated appendicitis, and during conservative treatment of an appendiceal infiltrate, ultrasound monitoring is performed to monitor the course of the inflammatory process in the abdominal cavity. It is advisable to perform ultrasound daily on days 1–3, then as clinically indicated and before discharge.

2.5 Other Procedures

When suspected of having AA, differential diagnosis should be performed within the framework of acute abdominal syndrome, ruling out diseases accompanied by fever, vomiting, and other functional gastrointestinal disorders.

Comments: Differential diagnosis of acute appendicitis within the framework of acute abdominal syndrome is most frequently conducted with viral infections accompanied by abdominal syndrome, nonspecific mesadenitis, gynecological pathology, and diseases of the gastrointestinal and urinary systems. If necessary, it is advisable to consult a pediatric gynecologist or urologist after ruling out acute surgical abdominal pathology, provided corresponding symptoms are detected via ultrasound or laparoscopy.

Comments: A cleansing enema in patients with suspected acute appendicitis helps determine the presence and characteristics of stool, and often resolves abdominal pain caused by functional bowel disorders (constipation, flatulence).

Comments: All patients requiring treatment in the ICU must undergo multi-parameter monitoring, including heart rate measurement, peripheral blood pressure measurement, respiratory rate measurement, pulse oximetry, electrocardiography, echocardiography, and abdominal ultrasound.

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

3.1 Conservative Treatment

Comments: Surgical treatment in the presence of a dense appendiceal infiltrate is associated with a high risk of abdominal organ injury, which makes conservative therapy advisable [3–10]. The findings of a review by R.E. Andersson et al. (2007), predominantly based on retrospective studies, support the practice of non-operative management without interval appendectomy in patients with an appendiceal abscess or infiltrate [51]. WSES considers interval appendectomy inappropriate in young individuals (< 40 years) and children [21].

In the Russian Federation, the practice of interval appendectomy following conservative treatment of an appendiceal infiltrate is generally accepted [3].

In the Russian Federation, conservative treatment of uncomplicated and complicated appendicitis, except for appendiceal infiltrate, is not recommended. However, numerous high-evidence studies worldwide demonstrate the feasibility of conservative antibiotic therapy for acute appendicitis in both adults and children [21, 57–62].

The working group for the development of these clinical guidelines considers that conservative therapy for acute appendicitis in children using antibacterial drugs is only possible within the framework of registered studies approved by an ethics committee in major clinical centers and supported by the Russian Association of Pediatric Surgeons (RAPS).

Comments: Secondary inflammatory changes in the appendix are generally associated with intra-abdominal inflammatory conditions (pelvioperitonitis, primary peritonitis, Meckel's diverticulitis, non-specific mesadenitis). All these conditions require antibacterial therapy, including mesadenitis when it presents with pronounced clinical manifestations. The primary cause of appendiceal changes in non-specific mesadenitis is lymphoid hyperplasia, which is a risk factor for the activation of the intrinsic intestinal microbiota and microbial translocation.

Comments: The course of infusion antibacterial therapy should be at least 48 hours, followed by a potential switch to oral administration, with the total duration being at least 7 days. Amoxicillin/clavulanic acid** or a combination of cephalosporins (ceftriaxone**, cefotaxime)** with metronidazole** is used as empirical therapy.

3.1 Surgical Treatment

To date, appendectomy remains the gold standard of treatment for complicated and uncomplicated destructive appendicitis, except for cases where removal of the vermiform appendix is impossible or extremely dangerous due to the risk of intestinal loop injury (appendiceal infiltrate, periappendicular abscess 3). Surgical intervention for acute appendicitis is performed on an emergency and urgent basis, taking into account the duration of dynamic monitoring. Prior to surgery, all patients must undergo the recommended minimum diagnostic examinations and, if necessary, preoperative preparation consisting of symptomatic therapy to correct homeostasis parameters. Preoperative preparation, including infusion therapy, may be required not only for children with complicated appendicitis, but also for patients with uncomplicated appendicitis presenting with pronounced intoxication syndrome.

Comments: The same drugs are used for antibiotic prophylaxis as for empirical antibacterial therapy. The antibacterial drug is administered within 30–60 minutes before the skin incision. If the duration of the surgery exceeds 3 hours, the drug is re-administered.

Comments: Preoperative preparation aims to correct severe metabolic and water-electrolyte disorders, which are manifestations of endotoxicosis and organ dysfunction in the development of peritonitis and sepsis. The duration and scope of preoperative preparation are determined by a joint consultation of an anesthesiologist-resuscitator and a pediatric surgeon. The baseline drugs for preoperative preparation are crystalloid solutions (solutions affecting the water-electrolyte balance). Preoperative preparation usually lasts 2–3 hours; in extremely severe conditions of the patient, it may be extended to stabilize the patient's condition, but it should not exceed 6 hours.

Comments: Surgical treatment can be performed via an open (appendectomy) or laparoscopic approach (appendectomy using video-endoscopic technologies, which is preferred) [11, 15, 17, 21, 48, 64] for appendectomy and peritoneal sanitation. WSES considers video-endoscopic appendectomy preferable in children when specialists and equipment are available, as the laparoscopic technique is associated with less postoperative pain, a lower rate of wound infection, and a higher quality of life [21]. In the case of periappendicular abscess 3, surgical treatment consists of its drainage.

Comments: In uncomplicated acute appendicitis, a delay in surgical treatment is possible provided the patient is kept in the hospital under the supervision of a pediatric surgeon [31, 32]. Postponing surgery for uncomplicated appendicitis is permissible if the surgical team is occupied with treating patients whose surgery cannot be delayed (internal bleeding, intracranial hematoma, mass casualty events, etc.). Modern studies show that in confirmed uncomplicated appendicitis, the delay in surgery should not exceed 24 hours, although it should be minimized whenever possible [21, 31, 32].

Comments: In complicated acute appendicitis, appendectomy must be performed as soon as possible, which corresponds to the time required for necessary preoperative preparation, usually 2–3 hours. In the group of critical patients who develop infectious-toxic shock, the time for stabilizing the patient's condition prior to surgery may be extended up to 6 hours until the patient's condition is stabilized. Surgical intervention in these cases must be performed in accordance with damage control principles.

Comments: Appendectomy can be performed as an open procedure (appendectomy) via a transverse or McBurney/Lanz incision or, preferably, laparoscopically (appendectomy using video-endoscopic technologies) [17, 21, 47, 48, 74-96]. Division of the mesoappendix during laparoscopic appendectomy is performed using mono- or bipolar coagulation or an ultrasonic scalpel-coagulator. Studies show no significant difference in outcomes, length of hospital stay, or complication rates among various methods of mesoappendix management (mono- or bipolar coagulation, ultrasonic energy transection, clipping, etc.). Monopolar coagulation is considered the cheapest and most effective method, whereas the ultrasonic scalpel causes the least thermal damage to surrounding tissues. Ligation of the appendix base prior to its transection without stump peritonization is advisable in both open and laparoscopic appendectomy (ligature technique). Literature reports exist on the use of a non-ligature appendectomy by vessel-sealing of the appendiceal stump [97].

Comments: Appendectomy is performed electively no earlier than 6–8 weeks, typically after 3–6 months. Recent reviews discuss the appropriateness of interval appendectomy following conservative management of an appendiceal mass or drainage of a periappendiceal abscess [49, 51, 52, 76]. Appendectomy can be performed via an open approach (transverse or McBurney/Lanz incision) or, preferably, laparoscopically (appendectomy using video-endoscopic technologies).

Comments: For periappendiceal abscess 3, opening and drainage of the abscess must be performed, whereas for total peritonitis, midline laparotomy is indicated (see explanations below).

Comments: Total (generalized) peritonitis is characterized by the involvement of all compartments of the abdominal cavity in the inflammatory process, with the formation of multiple loculated abscesses during the organization of free purulent effusion. This is the most severe form of appendiceal peritonitis, typically accompanied by abdominal sepsis, multiple organ dysfunction syndrome, and frequently infectious-toxic shock at the time of admission to the hospital. A pathognomonic feature of total peritonitis is the development of intestinal failure syndrome, which is the primary cause of intra-abdominal hypertension syndrome (IAHS) in this category of patients [17, 22, 72, 73]. Performing laparoscopy under such conditions is not only contraindicated but also impossible, as there is no free abdominal cavity, and any laparoscopic manipulations, including trocar insertion, carry a risk of bowel loop injury. Given the impossibility of effective single-stage peritoneal lavage in total peritonitis, "open" management of the abdominal cavity using vacuum-assisted laparostomy is advisable [17, 72, 73]. When grade 3 acute intestinal failure develops, small bowel intubation is indicated for effective intestinal decompression and resolution of IAHS [15, 17, 22, 72, 73].

Comments: When preoperative diagnosis reveals a periappendiceal abscess 3, it is necessary to perform its opening and abscess drainage without removing the appendix. If equipment and a specialist are available, it is advisable to perform percutaneous ultrasound-guided puncture and drainage of the abscess. Puncture and drainage of the abscess can be performed using a trocar-catheter or via the Seldinger technique. An 8–10 Fr tubular drain is used for drainage. After aspiration of purulent exudate under ultrasound guidance, the abscess cavity is washed with an antiseptic solution (e.g., 0.05% aqueous chlorhexidine** solution). The drain placed in the abscess cavity is connected to active suction (cavity drainage by active suction method). A Redon vacuum drain may be used. In the postoperative period, ultrasound monitoring of the drained area and daily checks to maintain drain patency are required. If necessary, additional ultrasound-guided flushing of the abscess cavity is possible (ultrasound-guided drainage of an intra-abdominal abscess). The drain (following ultrasound-guided drainage of the intra-abdominal abscess or opening and drainage of the phlegmon (abscess)) is left in place for 3–5 days (for long-standing, large-volume abscesses, the duration of drainage may be extended) until there is no purulent discharge through the drain and inflammatory changes regress according to ultrasound data. If a fecalith is present within the abscess cavity, its removal via extraperitoneal abscess opening is required. In case of a pelvic location of the abscess, it may be opened through the anterior wall of the rectum.

The 2020 WSES guidelines, based on meta-analyses and reviews published in recent years [21], discuss abscess drainage in cases where laparoscopic appendectomy is not feasible, and laparoscopic surgery when possible in high-volume laparoscopy centers with a low conversion rate.

The working group for the development of these guidelines considers it inappropriate to perform laparoscopic appendectomy for an appendiceal mass and periappendiceal abscess 3. Laparoscopic surgeries are safe and effective in early periappendiceal abscesses (PA 1, 2) [17, 50–52, 72].

Comments: Intraoperative peritoneal lavage is performed by irrigating the cavity with various solutions or by simple aspiration of peritoneal exudate in accordance with the hospital's internal protocol. Despite the lack of convincing advantages in research findings, including recent systematic reviews and meta-analyses, most researchers lean toward omitting peritoneal lavage and perform intraoperative sanitization solely by aspirating purulent effusion [11, 15, 21, 17, 56, 72, 86-89]. Regarding abdominal drainage, recent studies have likewise demonstrated no benefits [21, 90-96]. The 2020 WSES guidelines recommend performing only fluid aspiration during laparoscopic appendectomy and avoiding drains in complicated appendicitis [21].

3.2 Postoperative management

Comments: In uncomplicated acute appendicitis, postoperative antibiotic therapy is impractical [21]. In uncomplicated appendicitis, an equal incidence of infectious complications has been described in patient groups receiving and not receiving antibiotic therapy [62]. Perioperative antibiotic prophylaxis should be limited to 72 hours. Symptomatic pain relief with nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed, and an enema administered in the absence of stool.

Comments: The development of complications (appendiceal abscess, appendiceal peritonitis, intestinal failure syndrome) triggers a cascade of diverse pathological processes, leading to organ dysfunction, sepsis, and multiple organ dysfunction syndrome (MODS). The patient's critical condition, as well as the risk of its development, necessitates intensive care and multi-parameter patient monitoring. The main areas of intensive care include: correction of water-electrolyte and metabolic disorders, analgesia, antibacterial therapy, early nutritional therapy, and normalization of gastrointestinal function.

For postoperative analgesia, opioid analgesics (Morphine**, Trimeperidine**, Tramadol**), Metamizole sodium (ATC: N02B), Paracetamol (ATC: N02BE), non-steroidal anti-inflammatory and antirheumatic drugs (ATC M01A) (Ibuprofen** et al.), and epidural analgesia [33, 34] are used (Table 1).

Table 1 – Medicinal products for pain management

Comments: The infusion therapy program includes electrolyte solutions, plasma substitutes, and perfusion solutions (B05) as clinically indicated.

Comments: Empirical initial therapy involves protected penicillins or 2nd, 3rd, and 4th generation cephalosporins in combination with metronidazole. In total peritonitis complicated by sepsis, it is advisable to prescribe a de-escalation regimen of systemic antibacterial drugs (carbapenems in combination with glycopeptides). The approximate course of antibacterial therapy is 5-7 days for an uncomplicated postoperative period. Antibacterial therapy is discontinued in the absence of clinical and ultrasound-confirmed postoperative complications, normalization of body temperature and laboratory parameters (leukocyte and CRP levels). The antibacterial drug is changed when postoperative complications develop (intra-abdominal abscess, sepsis, wound suppuration) in accordance with the bacteriological data of peritoneal exudate and microbiological monitoring in the postoperative period (purulent focus, blood, patient's mucous membranes).

Comments: Parenteral nutrition products (B05BA) are generally prescribed from the 1st day of the postoperative period after the relief of shock reactions and stabilization of the patient's hemodynamics until the transition to enteral nutrition in the volume of physiological requirements and the restoration of the protein pool.

Comments: The main stages of early enteral therapy are decompression of the upper gastrointestinal tract (stomach, initial parts of the jejunum) using a nasogastric tube (nasogastric tube placement) or a dual-lumen nasointestinal tube (nasointestinal tube placement (157910 Nasoenteric tube)), and administration of an isotonic saline electrolyte solution into the stomach and/or small intestine (e.g., specialized dietary therapeutic food "Kit for preparing a specialized dietary therapeutic food (enteral nutrition) drink "SER" (saline enteral solution)") with a gradual transition to specialized nutrient formulas (oligomeric, polymeric — specialized enteral nutrition product for children, liquid complete balanced formula based on hydrolyzed whey proteins) as gastrointestinal function recovers. SER (saline enteral solution) can be used as the saline electrolyte solution. SER for enteral infusions includes sodium chloride**, sodium acetate, potassium chloride**, sodium phosphate, magnesium sulfate**, calcium chloride, and water. The saline electrolyte solution may additionally contain pectin, inulin, and glutamine, as well as citric acid as a stabilizer. SER allows for the effective regulation of the water-electrolyte balance of macronutrients during enteral infusions, significantly reduces the level of endogenous intoxication, and promotes the restoration of the intestinal barrier.

Comments: If gastrointestinal function is preserved, a surgical diet is prescribed from the 1st postoperative day. The transition to a general diet is typically carried out by the 3rd postoperative day. When postoperative acute intestinal obstruction develops, patients require early enteral tube therapy followed by a sparing diet. The transition to a general diet is carried out at a later date (after 7-10 days) as gastrointestinal function recovers.

4. Medical Rehabilitation and Sanatorium-Resort Treatment

Comments: In the postoperative period, therapeutic exercises (drainage breathing exercises, therapeutic exercises for colon diseases) and massage (general medical massage) are indicated for the prevention of postoperative complications. The choice of physical therapy depends on the type and scope of the surgical intervention and the course of the postoperative period. To improve reparative processes and prevent postoperative infectious complications, microwave resonance therapy (decimeter-range electromagnetic radiation therapy (microwave therapy)), magnetotherapy (general magnetotherapy), and laser therapy (low-intensity laser therapy (intravenous blood irradiation)) are used; for the normalization of intestinal motility, gastrointestinal electrical stimulation is applied.

5. Prevention and Dispensary Observation

6. Organization of Medical Care

Indications for hospital admission to a medical organization:

If acute appendicitis is suspected, emergency hospitalization in a pediatric surgical hospital is indicated.

Indications for discharging a patient from a medical organization:

• General condition of the child: satisfactory;

• Absence of complaints;

• No changes upon physical and laboratory examination;

• No complications according to abdominal ultrasound (comprehensive ultrasound examination of internal organs).

Recommended duration of hospitalization:

• Uncomplicated appendicitis: 5–7 days.

• Complicated appendicitis: 7–14 days.

7. Additional Information

No

Criteria for Evaluating the Quality of Medical Care

References

Appendix A1. Working Group Composition

Karaseva Olga Vitalievna, Doctor of Medical Sciences, Deputy Director for Scientific Work, Head of the Department of Polytrauma, Anesthesiology and Intensive Care at the Research Institute of Emergency Pediatric Surgery and Traumatology – Dr. Roshal Clinic, Chief Freelance Pediatric Specialist in Polytrauma of the Moscow Healthcare Department, member of the Russian Association of Pediatric Surgeons, Moscow, Russia

Mikhail Aleksandrovich Akselrov, Associate Professor, MD, PhD, Head of the Department of Pediatric Surgery, Tyumen State Medical University of the Russian Ministry of Health, Member of the Russian Association of Pediatric Surgeons, Tyumen, Russia. No conflict of interest.

Bairov Vladimir Gireevich, Doctor of Medical Sciences, Professor, Professor of the Department of Faculty Surgery with Clinic at the Almazov National Medical Research Centre of the Russian Ministry of Health, Chief Freelance Pediatric Surgeon of the Northwestern Federal District, member of the Russian Association of Pediatric Surgeons, St. Petersburg, Russia. There is no conflict of interest.

Barova Natalya Kaplanovna, Associate Professor, Candidate of Medical Sciences, Head of the Department of Pediatric Surgical Diseases at the Kuban State Medical University of the Russian Ministry of Health, Honored Healthcare Worker of Kuban, Honored Healthcare Worker of Adygea, Head of Surgical Department No. 1 at the Children's Regional Clinical Hospital of the Ministry of Health of Krasnodar Krai, Chief Freelance Pediatric Surgeon of the Ministry of Health of Krasnodar Krai, member of the Russian Association of Pediatric Surgeons, Krasnodar, Russia. There is no conflict of interest.

Barskaya Margarita Alexandrovna, Doctor of Medical Sciences, Professor, Professor of the Department of Surgical Diseases of Children and Adults at the Samara State Medical University of the Russian Ministry of Health, Chief Freelance Pediatric Surgeon of the Ministry of Health of Samara Region, member of the Russian Association of Pediatric Surgeons, Samara, Russia. There is no conflict of interest.

Bryantsev Alexander Vladimirovich, Candidate of Medical Sciences, Director of the Research Institute of Emergency Pediatric Surgery and Traumatology – Dr. Roshal Clinic, Honored Doctor of the RF, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest.

Golikov Denis Evgenievich, Researcher at the Department of Polytrauma at the Research Institute of Emergency Pediatric Surgery and Traumatology – Dr. Roshal Clinic, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest.

Golovanev Maxim Alexeevich, Candidate of Medical Sciences, Assistant at the Department of Pediatric Surgery, Pirogov Russian National Research Medical University, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest.

Gorelik Alexander Lvovich, Researcher at the Department of Polytrauma at the Research Institute of Emergency Pediatric Surgery and Traumatology – Dr. Roshal Clinic, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest.

Zhurilo Ivan Petrovich, Doctor of Medical Sciences, Professor, Professor of the Department of Pediatric Surgical Disciplines and Innovative Technologies in Pediatrics at the Orel State University named after I.S. Turgenev, member of the Russian Association of Pediatric Surgeons, Orel, Russia. There is no conflict of interest

Morozov Dmitry Anatolyevich, Doctor of Medical Sciences, Professor, Head of the Department of Pediatric Surgery and Urology-Andrology at Sechenov University, Director of the Academician Yu.E. Veltischev Research and Clinical Institute of Pediatrics and Pediatric Surgery, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Nalivkin Alexander Evgenievich, Doctor of Medical Sciences, Professor, Head of the Pediatric Surgery Course at the Department of Surgery of the Moscow Regional Research Clinical Institute named after M.F. Vladimirsky, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Poddubny Igor Vitalievich, Doctor of Medical Sciences, Professor, Head of the Department of Pediatric Surgery at the Yevdokimov Moscow State University of Medicine and Dentistry of the Russian Ministry of Health, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Razumovsky Alexander Yuryevich, Doctor of Medical Sciences, Professor, Corresponding Member of the RAS, Head of the Department of Pediatric Surgery at the Pirogov Russian National Research Medical University of the Russian Ministry of Health, President of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Svarich Vyacheslav Gavrilovich, Doctor of Medical Sciences, Professor of the Department, Honored Doctor of the RF, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Smirnov Alexey Nikolaevich, Doctor of Medical Sciences, Professor of the Department of Pediatric Surgery at the Pirogov Russian National Research Medical University of the Russian Ministry of Health, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Sokolov Yury Yuryevich, Doctor of Medical Sciences, Professor, Head of the Academician S.Ya. Doletsky Department of Pediatric Surgery at the Russian Medical Academy of Continuous Professional Education of the Russian Ministry of Health, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Timofeeva Anna Vyacheslavovna, Researcher at the Department of Polytrauma at the Research Institute of Emergency Pediatric Surgery and Traumatology – Dr. Roshal Clinic, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Tsap Natalya Alexandrovna, Doctor of Medical Sciences, Professor, Head of the Department of Pediatric Surgery at the Ural State Medical University of the Russian Ministry of Health, Chief Freelance Pediatric Surgeon of the Ministry of Health of Sverdlovsk Region; Chief Freelance Pediatric Surgeon for the Ural Federal District, member of the Russian Association of Pediatric Surgeons, Moscow, Russia. There is no conflict of interest

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience for these clinical guidelines:

• Pediatric surgeons in inpatient and outpatient settings;

• Surgeons providing emergency medical care to children;

• Pediatricians;

• Anesthesiologists-intensivists;

• Lecturers at medical educational institutions;

• Students, residents, postgraduate students, continuing education course attendees.

Table 1. Level of Evidence (LoE) grading scale for diagnostic methods (diagnostic interventions)

Table 2. Level of Evidence (LoE) grading scale for prevention, treatment, and rehabilitation methods (preventive, therapeutic, and rehabilitative interventions)

Table 3. Grade of Recommendation (GoR) scale for prevention, diagnostic, treatment, and rehabilitation methods (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision at least once every three years, as well as upon the emergence of new evidence-based medicine data on the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

• Order of the Ministry of Health of the Russian Federation No. 562n dated October 31, 2012 "On Approval of the Procedure for Providing Medical Care in the Profile 'Pediatric Surgery'."

• Order of the Ministry of Health of the Russian Federation No. 203n dated May 10, 2017 "On approval of criteria for assessing the quality of medical care."

• Order of the Ministry of Health of the Russian Federation No. 1134n dated October 20, 2020 "On approval of the procedure for medical examination of the recipient, performing individual compatibility tests, including the biological test, during transfusion of donor blood and (or) its components".

Appendix B. Physician Action Algorithms

Note: AA – acute appendicitis, AI – appendicular infiltrate; PA – periappendiceal abscess;

LA – laparoscopic appendectomy; OA – open appendectomy

Appendix C. Patient Information

Acute appendicitis is a surgical condition where delayed medical care can lead to severe complications and even death. The patient and parents must know that if acute abdominal pain occurs, self-treatment is unacceptable; medical assistance must be sought immediately at a medical facility or an ambulance should be called.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

1. Russian name: Alvarado score

Key (interpretation): 0-4 – unlikely; 5-6 – possible; 7-8 – probable; > 9 – highly probable

Notes: none

2. Russian name: Pediatric Appendicitis Score

Original name: Pediatric appendicitis score (PAS)

Source (official developer website, validation publication):

Samuel M. Pediatric appendicitis score. J Pediatr Surg. 2002 Jun;37(6):877-81. doi: 10.1053/jpsu.2002.32893. PMID: 12037754.

Type (underline): - scale

- index

- questionnaire

- other (specify): _______________

Purpose: predicts the probability of an acute appendicitis diagnosis

Content (template):

Key (interpretation): < 5 – unlikely; 5 – possible; > 6 – probable

Notes: for patients aged 3–18 years

3. Russian name: Appendicitis Inflammatory Response score

Original name: Appendicitis Inflammatory Response score (AIR)

Source (official developer website, validation publication): Andersson, M. and Andersson, R.E. (2012), Erratum to: The Appendicitis Inflammatory Response Score: A Tool for the Diagnosis of Acute Appendicitis that Outperforms the Alvarado Score. World J Surg, 36: 2269-2270 1. https://doi.org/10.1007/s00268-012-1679-9

Type (underline): - scale

- index

- questionnaire

- other (specify): _______________

Purpose: predicts the probability of an acute appendicitis diagnosis

Content (template):

Key (interpretation): 0-4 – low probability; 5-8 – moderate; 9-12 – high

Notes: Used in pediatric or adult patients with suspected appendicitis (large external validation cohort included ages 2–96 years)