Acute intestinal obstruction of tumor etiology: clinical guidelines

List of Abbreviations

BP – blood pressure

RF – respiratory failure

GI - gastrointestinal tract

CT – computed tomography

ABR – acid-base balance

CBC – complete blood count

AIO - acute intestinal obstruction

Ultrasound – ultrasound examination

CKD – chronic kidney disease

CHF – chronic heart failure

RR – respiratory rate

HR – heart rate

Rg – radiography

ScvO2 – central venous oxygen saturation

SpO2 – arterial blood oxygen saturation

Terms and Definitions

Endotoxemia, or endogenous intoxication syndrome is a complication of various diseases associated with impaired homeostasis due to the accumulation of endogenous toxic substances in the body, including bacterial endotoxins with pronounced biological activity.

Peritoneal carcinomatosis – a form of metastasis of abdominal and pelvic organ cancer, characterized by the appearance of tumor foci on the visceral and parietal peritoneum.

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

Tumor-induced intestinal obstruction is a syndrome characterized by impaired passage of contents through the digestive tract, caused by a mechanical obstacle represented by a malignant or benign neoplasm of the intestine.

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

Acute intestinal obstruction of tumor etiology refers to obturation obstruction, and in the overwhelming majority of cases, its cause is located in the colon. Much less frequently, AIO is caused by malignant neoplasms of the small intestine and benign tumors of the bowel. Obturation may occur due to the overlapping of the intestinal lumen either by a primary bowel tumor or by external compression from a tumor originating in adjacent organs and tissues.

The most characteristic feature is a subtle, slowly progressive onset in the form of impaired transit due to incomplete occlusion of the intestinal lumen. An acute onset may be caused by complete obturation of the narrowed area by a tumor or dense fecal masses.

In the early stage of obstruction, peristalsis increases, with the bowel striving to overcome the emerging obstacle through contractions. At this stage, peristaltic movements in the afferent loop shorten in length but become more frequent. Subsequently, as a result of sympathetic nervous system hypertonus, bowel overdistension, and a sharp depression of tissue perfusion, a phase of significant suppression of intestinal motor function occurs, and in late stages of obstruction, complete paralysis develops. Metabolic disorders of the intestinal wall tissue exacerbate the escalating endogenous intoxication, which in turn increases tissue hypoxia.

Water-electrolyte disturbances are associated with the loss of large amounts of fluid, electrolytes, and proteins. Fluid is lost through vomiting, pooled in the afferent section of the intestine, accumulated in the edematous intestinal wall and its mesentery, as well as in the free abdominal cavity. Daily fluid losses can reach 4 L or more. Electrolyte balance disruption occurs, primarily potassium loss. Along with fluid and electrolytes, significant amounts of protein (up to 300 g/day) are lost due to starvation, vomiting, sequestration into the intestinal lumen and abdominal cavity. Impairment of the intestinal wall barrier function leads to bacterial translocation into the portal bloodstream, lymph, and peritoneal exudate. These processes underlie the systemic inflammatory response and abdominal surgical sepsis characteristic of acute intestinal obstruction.

A significant role in the pathogenesis of intestinal obstruction is played by intra-abdominal hypertension (compartment syndrome), leading to impaired blood supply to internal organs, decreased tissue viability, and multiple organ failure. The main principles of compartment syndrome treatment are early surgical decompression and rational infusion therapy.

1.3 Epidemiology of the Disease or Condition

Colon cancer is one of the most common forms of malignant neoplasms both in Russia and worldwide [1; 2]. Acute intestinal obstruction is a complication of colorectal cancer that occurs in 15–20% of patients and can be observed in all age groups, but more frequently in patients over 50 years of age. In the Russian Federation, an annual increase in the number of patients with tumor-related acute intestinal obstruction is registered. According to 2019 data, 22,221 cases of AIO were detected in Russia, with hospital and postoperative mortality rates of 15.39% and 17.05%, respectively [3].

1.4 Features of Coding the Disease or Condition

Class - Diseases of the digestive system (XI):

K56.6 - Other and unspecified intestinal obstruction

1.5 Classification of the disease or condition

To date, there is no universally accepted classification of tumor-related intestinal obstruction.

The Working Group on the Creation of Clinical Guidelines for the Treatment of Patients with AIO of Tumor Etiology has proposed dividing it depending on the degree of compensation [4]:

▪ compensated AIO: intermittent stool retention and difficulty passing gas; abdominal plain radiography may reveal colonic pneumatization with isolated fluid levels within it;

▪ subcompensated AIO: stool and gas retention for less than 3 days, plain radiography reveals pneumatosis and Klatskin/Kloiber's sign – horizontal fluid levels with dome-shaped radiolucency (gas) above them; no signs of multiple organ dysfunction; conservative therapy is effective;

▪ decompensated AIO: stool and gas retention for more than 3 days; radiological signs of both colonic and small bowel obstruction with localization of small bowel fluid levels and arches throughout all regions of the abdominal cavity; vomiting of stagnant contents; presence of organ dysfunctions.

However, scientific evidence supporting the validity of using this classification to determine surgical tactics in patients with intestinal obstruction is insufficient.

The ColoRectal Obstruction Scoring System (CROSS) classification proposed by The Japan Colonic Stent Safety Procedure Research Group (JCSSPRG) does not provide for its use as a tool to determine the timing and type of treatment for intestinal obstruction [5].

To determine the urgency of surgical treatment, patient stratification by stability in accordance with sepsis (septic shock) criteria is necessary.

Organ dysfunction, which may be caused by intestinal obstruction or perforation, is defined as a criterion for sepsis. Patients with sepsis due to bowel perforation against the background of intestinal obstruction require emergency surgical treatment. It is reported that a surgical delay of over 6 hours in patients with septic shock due to gastrointestinal perforation is accompanied by zero 60-day survival [6]. Criteria for patient instability corresponding to sepsis were proposed in the guidelines of The World Society of Emergency Surgery (WSES) when determining treatment tactics for obstructive colonic obstruction [7]. To assess organ dysfunction, the use of the Sequential Organ Failure Assessment (SOFA) and quick SOFA scales is recommended.

Examples of diagnosis formulation:

1. "Sigmoid colon cancer complicated by acute intestinal obstruction."

2. "Ascending colon cancer complicated by acute intestinal obstruction."

A more precise formulation of the diagnosis using the international TNM classification is possible upon obtaining data on the morphological structure and extent of the tumor process.

1.6 Clinical presentation of the disease or condition

Clinical manifestations of tumor-related AIO are diverse and depend on many factors. The most common of these are abdominal pain, abdominal distention, and absence of stool and gas passage.

2. Diagnostics, medical indications and contraindications for diagnostic methods

A wide variety of different diseases and their clinical forms can lead to the development of acute intestinal obstruction syndrome [98-102]. However, the diagnosis is established based on data that are uniform for all conditions: complaints and clinical examination findings (abdominal distension, cramping abdominal pain, cessation of stool and gas passage, nausea, vomiting), as well as data from laboratory and instrumental research methods (plain radiography [103]; abdominal ultrasound [104]; abdominal computed tomography [105]). At the same time, diagnostic measures are universal, regardless of the underlying disease, and boil down to the following main stages: exclusion of conditions requiring immediate surgical intervention (strangulation, perforation, peritonitis, etc.); differential diagnosis of mechanical and paralytic obstruction; determination of the level and cause of the obstruction.

Identifying perforation, strangulation, and septic shock is a priority task of the diagnostic stage in patients with intestinal obstruction.

It has been established that delaying surgical intervention for more than 6 hours in bowel perforation and septic shock is associated with 100% 60-day mortality [6]; therefore, an important goal of initial diagnosis and monitoring during non-operative treatment is the early detection of perforation or the threat of colon perforation. At the same time, the role of time to surgery in stable patients without peritonitis should not be overestimated. A direct correlation between surgical delay in acute intestinal obstruction and 30-, 90-day, as well as 1-year mortality has not been established [8].

2.1 Complaints and Anamnesis

Acute intestinal obstruction usually occurs suddenly, manifesting as a lack of gas passage and abdominal distension. Abdominal distension and the absence of gas passage are pathognomonic symptoms of acute intestinal obstruction.

Abdominal pain is an inconstant symptom of acute intestinal obstruction; it can be cramping, with periods of intensification during a peristaltic wave. As the disease progresses, intestinal peristaltic activity decreases, which is why pain, as a rule, changes its character from cramping to constant by the 2nd–3rd day, serving as a poor prognostic sign.

Vomiting may be absent in the early stages of acute intestinal obstruction, later becoming recurrent and bringing no relief. In the late period, vomitus acquires the appearance and smell of intestinal contents.

2.2 Physical Examination

Upon admission of a patient with suspected acute intestinal obstruction to the hospital, a clinical examination is performed first, during which the condition of the skin is assessed, body mass index is calculated, thermometry, pulse measurement, respiratory rate, and blood pressure are measured. Auscultation, percussion, and palpation of the abdomen are performed. Digital rectal examination is performed in all patients, and a vaginal examination is additionally performed in women.

2.3 Laboratory Diagnostics

There is no specific laboratory diagnostics for acute intestinal obstruction of tumor etiology.

The basis of laboratory diagnostics in acute intestinal obstruction is the detection of systemic disorders requiring correction and additional therapy. In the complete blood count, it is necessary to pay attention to the presence or absence of anemia, which may be one of the markers of postoperative complications or a sign of chronic blood loss, and to the presence or absence of leukocytosis and changes in the leukocyte formula as markers of a systemic inflammatory response and translocation of microflora through the distended intestinal wall. A blood chemistry panel and determination of serum electrolytes allow for the detection of water and electrolyte disorders occurring during the development of intestinal failure syndrome as a result of bowel lumen obstruction, as well as changes in liver enzymes and nitrogenous bases, which may indicate the development of hepatorenal failure as a consequence of vomiting, dehydration, and endotoxemia against the background of intestinal failure [9].

2.4 Instrumental Diagnostics

• Patients with suspected acute obturation intestinal obstruction in the absence of contraindications are recommended to undergo computed tomography of the chest, abdomen, and pelvis as the method of choice [10].

LoR CGoE 5Level of Recommendation C (Grade of Evidence - 5)

Comments: Performing abdominal computed tomography in patients with suspected acute obturation intestinal obstruction makes it possible to suspect the tumoral nature of the obstruction, establish the stage of the oncological process, the presence of distant metastases, the extent of the pathological process in the colon [10], exclude free gas in the abdominal cavity, and detect the presence of gas bubbles in the pericolic fat as an early radiological symptom of tumor perforation of the bowel wall and other complications of acute intestinal obstruction. Limitations of the method include the patient's contraindications to the use of iodine-containing radiopaque agents (drug intolerance, elevated blood urea and creatinine levels), and the inability to transport the patient to the radiology department. In such cases, preference in diagnostics is given to ultrasound and/or radiological examination of the abdominal organs [11–13].

• All patients with suspected acute obturation intestinal obstruction, when computed tomography cannot be performed, are recommended to undergo ultrasound examination of the abdominal and pelvic organs and plain radiography of the abdominal organs [14].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comments: If abdominal computed tomography cannot be performed, the diagnostic algorithm includes transabdominal ultrasound of the abdominal cavity and plain abdominal radiography. Ultrasound is an operator-dependent examination method, but in the presence of an experienced physician, it is more effective than X-ray examination and can also be performed in the hospital ward without requiring patient transportation [13;15].

• All patients with suspected acute obturation intestinal obstruction determined by ultrasound and plain abdominal radiography, when computed tomography cannot be performed, are recommended to undergo irrigoscopy using water-soluble nephrotropic high-osmolar radiopaque agents (V08AA01 Sodium amidotrizoate) [16;17].

Level of Evidence CQuality of Evidence 2Strength of Recommendation - C (Level of Evidence - 2)

Comments: If acute obturation intestinal obstruction is suspected based on abdominal ultrasound and plain abdominal radiography, and computed tomography cannot be performed, it is advisable to perform irrigoscopy (A06.18.001) with a water-soluble contrast agent to determine the level of obstruction. Barium sulfate** contrast enema is not recommended because it subsequently complicates the visualization of the intestinal mucosa during colonoscopy [17;18].

Comments: During colonoscopy, the diameter of the tumor stenosis and the feasibility of bowel stenting are assessed, and tumor tissue is harvested for pathomorphological examination. To prepare the bowel for examination, cleansing enemas are preferred; performing them in some cases allows for the resolution of intestinal obstruction, yet it can cause diastatic perforation of the proximal colon. Preoperative colonoscopy is not recommended in unstable patients, as well as when the cecal dome is dilated by more than 10 cm due to the high risk of bowel perforation during the procedure [20]. In such cases, colonoscopy should be performed in the postoperative period to rule out neoplasms in other parts of the colon [7]. To reduce the risk of bowel perforation, insufflation using CO₂ is preferred [21].

2.5 Other Procedures

No.

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

The main goal of medical care for patients with acute intestinal obstruction of tumor etiology is the elimination of intestinal obstruction, which creates favorable conditions for the prompt initiation of oncologically sound treatment.

Surgery is the main method of treatment for tumoral intestinal obstruction. The scope, urgency, and phased nature of surgical treatment depend on the technical equipment of the medical institution, the training of the surgical, anesthesiological, and resuscitation teams, the patient's functional status and the degree of surgical and anesthesiological risk, the prevalence and presence of complications of the oncological disease, including perforation with the formation of peritonitis, abscess, sepsis, and septic shock.

3.1 Conservative therapy

Non-operative treatment is a preparatory stage for surgery and, unlike small bowel obstruction, is not considered an independent definitive method for treating tumoral intestinal obstruction.

• Patients with acute colonic obstruction (ACO) without signs of intestinal perforation may be recommended initial non-operative treatment aimed at preparation for surgery under the most favorable conditions [20].

GoR CLoE 5Grade of Recommendation - C (Level of Evidence - 5)

Comment: to achieve optimal conditions, it is necessary to correct fluid and electrolyte imbalances, anemia, and nutritional status, and to provide a qualified anesthetic and surgical team. Indications for immediate surgical treatment include persistent acidosis and cecal dome dilation greater than 10 cm, which indicates a risk of perforation. In the absence of signs of intestinal wall compromise, treatment may be continued to achieve optimal conditions with laboratory and instrumental monitoring every 6–12 hours [20].

• All patients with ACO should undergo correction of hypovolemia and fluid-electrolyte imbalances [22, 23].

GPP CLOE 2Level of Evidence – C (Level of Confidence in Recommendations - 2)

Comment: hypovolemia can have catastrophic consequences for surgical patients and is a major factor in preventable mortality. Preoperative hypovolemia should be corrected whenever possible. Balanced crystalloid solutions (solutions affecting electrolyte balance, ATC code B05BB) should be preferred at the initial stage of hypovolemia correction [22].

• Patients with ACO presenting with symptoms of gastrostasis are recommended to undergo decompression of the upper gastrointestinal tract by aspiration of contents via a nasogastric or nasointestinal tube [20, 24].

GCP CLOE 5Grade of Recommendation – C (Level of Evidence – 5)

Comment: although in international guidelines [7] for acute colonic obstruction, unlike small bowel obstruction, the procedure of preoperative gastrointestinal decompression is not described, its use in mixed (small-colonic) obstruction allows expecting a reduction in intra-abdominal pressure, the concentration of the microbial flora, and the toxic effect of stagnant contents of the stomach and small intestine. The recommendation for preoperative GI decompression may be relevant primarily in tumors of the right colon manifesting as small bowel obstruction with dilatation of the proximal GI tract. In left-sided acute colonic obstruction, dilatation of the proximal small intestine and stomach is less common; therefore, in the absence of stagnant contents in the stomach, there is no need to insert a tube for upper GI decompression. A domestic study found no effect of gastric decompression on the survival of patients with small bowel obstruction [25]. However, preliminary GI decompression facilitates manipulations in the abdominal cavity. Therefore, GI decompression using a nasogastric (intestinal) tube may be recommended.

• All patients with ACO are recommended to discontinue enteral nutrition [26].

GCP CLOE 5Grade of Recommendation – C (Level of Evidence – 5)

Comment: enteral nutrition exerts a trophic effect on the intestinal epithelium, prevents mucosal atrophy, and prevents bacterial translocation. However, enteral nutrition is contraindicated in cases of gastrointestinal obstruction, perforation, or intestinal wall ischemia [26].

• All patients with ACO are recommended to undergo evaluation of treatment efficacy: clinical evaluation every 6 hours, and instrumental evaluation (plain abdominal radiography or ultrasound) every 12 hours [6, 19, 20].

CGR CLOE 5Level of Clinical Guidance - C (Level of Evidence - 5)

Comment: the most important clinical signs of improvement and conservative resolution of ACO include the restoration of passage of gas and spontaneous bowel movements. Criteria for discontinuing non-operative treatment include clinical and radiological findings indicating intra-abdominal complications (perforation), elevated lactate (serum lactate >2 mmol/L), leukocytosis (>18×10⁹/L), temperature >38.5°C, and a rise in creatinine (more than 2-fold compared to admission) [20]. In addition, cecal dome dilation >10 cm and refractory acidosis should be considered indications for emergency surgery [20]. The decision on whether to continue conservative therapy must be made every 6 hours. It has been shown that delaying surgery by more than 6 hours in cases of intestinal perforation and septic shock is associated with 100% 60-day mortality [6].

• Unstable patients with ACO, peritonitis, and septic shock are recommended to undergo surgery after intensive care and stabilization of their condition [27].

GCR CLOE 3Level of recommendation evidence - C (level of data reliability - 3)

Comment: patients with intestinal obstruction, peritonitis, and septic shock require intensive preoperative therapy. Risk factors for mortality include hypothermia (below 35 °C), metabolic acidosis, and the presence of clinical or laboratory signs of coagulopathy [27]. In addition, comorbid patients and individuals over 70 years of age require intensive care [28]. Target stabilization parameters include the restoration of central venous pressure to 8–12 mm Hg, mean arterial pressure >65 mm Hg, and central venous oxygen saturation (ScvO₂) >70% [29;30]. Management of unstable patients with intestinal obstruction should be carried out in an intensive care unit.

• Patients with confirmed intestinal perforation and peritonitis should be recommended antibacterial therapy as early as possible [31–33].

LoR ALoE 1Level of Recommendation — A (Level of Evidence — 1)

Comments: intra-abdominal infections caused by colonic perforation are frequently caused by a mixture of aerobic and anaerobic bacteria. Antimicrobial therapy recommended for intra-abdominal infections [31], includes carbapenem monotherapy and combination therapy with metronidazole** and third-generation cephalosporins or fluoroquinolones. Although metronidazole** has been used as standard therapy for trichomoniasis, anaerobic and amoebic infections worldwide since the 1970s, resistance to metronidazole** remains low [33]. It has been shown that combination therapy with metronidazole** can be an effective and safe treatment option for intra-abdominal infections, comparable to carbapenem monotherapy [32].

• For the prevention of thromboembolic events in patients with acute obstructing tumors of the colon (AOTC), the administration of heparin preparations and the use of compression stockings are recommended [34].

GCR BLOC 1Grading of Recommendations Assessment, Development and Evaluation (GRADE) level of recommendation - B (level of evidence - 1)

Comment: patients undergoing surgery for colorectal cancer are at high risk for thromboembolic complications. In the presence of bowel obstruction, the risk of such complications is considered extremely high. The use of low-molecular-weight heparins (ATC: heparin group) can significantly reduce the probability of deep vein thrombosis of the lower extremities and pulmonary embolism. The use of other heparin preparations does not differ in efficacy, but is associated with a higher rate of hemorrhagic complications and the development of heparin-induced thrombocytopenia. Additionally, compression stockings and intermittent pneumatic compression devices are used. At the same time, early mobilization is one of the prerequisites for successful venous thrombosis prevention and is practiced whenever possible. In patients undergoing major oncological surgeries, it is advisable to continue preventive measures combined with low-molecular-weight heparin administration for at least 4 weeks [35, 36].

3.2 Non-surgical treatments

No.

3.3 Surgical Treatment

The primary objective of surgical treatment for ACO is to save the patient's life from complications of colon cancer and to create favorable conditions for the prompt initiation of oncologically sound treatment. Colonic tumor resection in ACO should be performed only when necessary to save the patient's life, or when the potential risk of a staged treatment approach outweighs the benefits of a single-stage procedure.

There are two options for the surgical treatment of acute colon obstruction (ACO), namely: 1) initial colonic decompression followed by elective colonic resection; 2) primary colonic resection. Colonic decompression can be achieved by constructing a proximal intestinal stoma, placing a stent, or inserting a decompression colonoscopic catheter (colorectal tube, referred to in English-language literature as the "Dennis Colorectal Tube"). Primary resection procedures include obstructive segmental resection of the colon without anastomosis (Hartmann's procedure, right hemicolectomy with an end ileostomy/ileoascending ileostomy), subtotal colectomy, and segmental colonic resection with primary anastomosis. The choice of the optimal surgical approach remains controversial, and the search for optimal treatment strategies is ongoing.

3.3.1 Endoscopic minimally invasive decompression interventions

Minimally invasive surgical treatments for tumor-induced ACO include self-expandable stent placement and the insertion of a colonoscopic decompression catheter proximal to the colonic tumor. Resolving the intestinal obstruction helps avoid emergency or urgent surgery, enabling additional therapeutic and diagnostic measures to prepare the patient for elective surgery, including a laparoscopic approach. Relieving acute intestinal obstruction at the initial stage of complicated colorectal cancer treatment reduces the risk of severe complications and mortality, creates conditions for primary anastomosis creation, and in some cases avoids a diverting stoma [37].

3.3.1.1 Endoscopic stenting for tumor stenosis

The most common non-invasive treatment for relieving ACO is colonic stenting using a self-expandable mesh system (uncovered metal colonic stent) inserted endoscopically into the lumen at the tumor level.

• In the absence of signs of perforation, peritonitis, bleeding, or complete luminal occlusion by a left-sided colon tumor, it is recommended to place a self-expandable metal stent (uncovered metal colonic stent) [38].

GoR BLoE 2Grade of recommendation - B (level of evidence - 2)

Comment: the technical success rate of the procedure is 80–100%, while clinical improvement is observed in 73–89% of patients. The most dangerous complication of stenting is perforation, which occurs in 12.8% of cases, with "silent" perforation detected only on instrumental examination occurring in 26.7% of cases [39]. Tumor perforation during stenting is an unfavorable prognostic factor [40], and stenting is more frequently followed by lymph node involvement and perineural tumor invasion [41]. However, given sufficient stenting experience (at least 40 procedures) and radical surgical resection of the colonic tumor within 14 days, overall and disease-free survival rates in the stenting and primary resection groups do not differ [38;42], while the rates of anastomotic leakage and stoma formation are lower with stenting [43]. Earlier guidelines did not recommend the routine use of this treatment due to concerns about worsening long-term outcomes [44].

• To prevent obstruction recurrence, radical surgery is recommended to be performed within 14–30 days after ACO relief in patients who do not require additional treatment, including neoadjuvant medical therapy and/or radiation therapy [45].

GoR BLoE 3Grade of recommendation - B (level of evidence - 3)

Comment: following stenting, no significant differences in post-resection complications, length of hospital stay, or laparoscopic resections were observed when surgery was performed at 11–17 days compared to 5–10 days. Of the stent-related complications, 48% occurred in patients operated on more than 17 days after decompression. Compared to interventions performed within 14 days after stomy creation, surgeries performed 14–28 days after decompression were associated with a significantly higher number of laparoscopic resections, a greater number of primary anastomoses, and a shorter hospital stay. The timing of radical surgery showed no impact on mortality, disease-free survival, or overall survival [45].

• Tumor stenting for ACO during ongoing anti-tumor therapy with monoclonal antibodies inhibiting vascular endothelial growth factor (VEGF) biological activity (bevacizumab**) is not recommended [46].

GoR BLoE 2Grade of recommendation - B (level of evidence - 2)

Comment: the presence of a stent in the tumor channel in patients receiving long-term bevacizumab** therapy is associated with a high risk of tumor perforation [46].

• In patients with bowel obstruction caused by a tumor of the lower- and mid-ampullary rectum, stenting is not recommended [47].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: in low-lying rectal cancer, the dentate line may fall within the stenting zone, causing severe pain, bleeding, tenesmus, and fecal incontinence [47].

3.3.1.2 Retrograde passage of a decompression colonoscopic catheter

The method involves transanal insertion of a decompression colonoscopic catheter through the tumor channel followed by lavage of the proximal colon. It is performed during colonoscopy under fluoroscopic guidance.

• In the absence of signs of perforation, peritonitis, bleeding, and complete luminal occlusion by a left-sided colon tumor, as an alternative to stenting, it is recommended to place a decompression colonoscopic catheter [48].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: insertion of a radiopaque tube is feasible when the tumor channel diameter is at least 3 mm. The technical success rate of the method is 80%, clinical success is 72.5%; the rate of bowel perforation can reach 10%.

A potential advantage of the method is the possibility of lavage of the proximal colon and, presumably, less trauma to the bowel in the tumor area due to the absence of tumor channel dilation that occurs with stenting. A significant limitation to its use is the lack of data on its oncological safety [43].

3.3.2 Surgical treatment

The primary objective of surgical treatment for ACO is to relieve intestinal obstruction and save the patient's life. If a colorectal cancer surgeon or coloproctologist is available at the medical facility, the decision on the scope of surgical treatment is made based on individual patient characteristics—in the absence of peritonitis, both resectional and decompressive interventions (intestinal stoma) are acceptable. A rational surgical approach for ACO in non-specialized hospitals is the formation of a proximal stoma followed by radical surgical removal of the colonic tumor, which is preferably performed in specialized oncocoloproctology centers.

• An indication for terminating further therapy and performing urgent surgery is persistent acidosis and/or cecal dome dilation exceeding 10 cm [20].

CGR CLOE 5Level of Clinical Guidance - C (Level of Evidence - 5)

Comment: indications for emergency surgical treatment include cecal dome dilatation greater than 10 cm due to the risk of perforation, as well as uncorrectable acidosis [20].

• All patients scheduled for intestinal stoma formation are recommended to have the prospective stoma site marked preoperatively [49].

GoR CLoE 5Grade of Recommendation - C (Level of Evidence - 5)

Comment: if a stomy is planned for the patient, the procedure itself and its consequences must be thoroughly explained. The proposed stoma site must be marked. Preoperative consultation with an ostomy care nurse is optimal. In emergency situations, it is not always possible to follow the above recommendations; in such cases, the marking of the proposed stoma site must be performed by the operating surgeon. Marking is performed with the patient in standing, supine, and sitting positions, taking into account individual and constitutional features, in accordance with clinical guidelines for the management of patients with an intestinal stoma [50].

• Patients without signs of bowel perforation, peritonitis, abscess formation, undergoing surgery for tumor-induced ACO, are recommended to receive antibiotic prophylaxis with systemic antibacterial drugs (ATX J01) [51].

LoR ALoE 1Level of Recommendation — A (Level of Evidence — 1)

Comment: a single administration of a broad-spectrum antibacterial drug is considered effective (ATC: J01CA Broad-spectrum penicillins, J01DC Second-generation cephalosporins, J01DD Third-generation cephalosporins, J01DE Fourth-generation cephalosporins, J01DH Carbapenems, J01M Quinolone antibacterial drugs) immediately before surgery, and its repeated administration if the surgical intervention lasts more than 3 hours. The administration of systemic antibacterial drugs can reduce the incidence of infectious complications, shorten the hospital stay, and lower the costs of treating postoperative complications [51].

• All patients with acute intestinal obstruction are recommended to undergo intraoperative small bowel decompression [49].

GoR CLoE 5Grade of Recommendation - C (Level of Evidence - 5)

Comment: small bowel decompression is necessary to eliminate abdominal compartment syndrome, provide conditions for tension-free closure of the abdominal wall wound, reduce the concentration of microbial flora, eliminate the toxic effect of stagnant gastric and small bowel contents, normalize respiratory function, reduce the risk of aspiration pneumonia, improve intestinal wall perfusion, and restore the motor and absorptive functions of the intestine.

According to a systematic review, there are no statistically significant differences in treatment outcomes for patients with acute intestinal obstruction when using a nasogastric tube with manual small bowel decompression versus "open" bowel decompression [52]. In the treatment of small bowel obstruction, based on the meta-analysis results, the use of a nasointestinal tube has no advantages over a nasogastric tube [53].

The choice of digestive tract decompression method should be decided individually for each patient, based on the characteristics of their disease, and the experience of the medical institution and the operating surgeon.

3.3.2.1 Formation of a loop stoma.

The creation of a loop ileostomy/colostomy is an alternative to stenting in the "bridge to surgery" strategy, when treatment is aimed solely at resolving acute intestinal obstruction in order to create optimal conditions for the main stage of surgical intervention — resection of the colon tumor [37;54].

• In case of ineffective ongoing treatment, absence of signs of peritonitis, and also as an alternative to stenting, it is recommended to perform surgery in the volume of proximal loop bowel stoma formation [55–57] .

GOM BLOE 2Grade of Recommendation - B (Level of Evidence - 2)

Comment: the advantage of a loop stoma is the relative simplicity of the operation, reliable decompression of the colon, and the possibility of performing total colonoscopy (when a double-barreled colostomy is formed), which allows detection of a synchronous neoplasm in 2.3–12.4% of cases [55]. The choice between ileostomy and colostomy is decided individually, depending on the specific clinical situation. The complication rate is comparable for both options, however, patients with an ileostomy have a higher risk of developing dehydration [56]. It has been shown that patients who underwent loop stoma formation as the first stage had a statistically significantly lower rate of having a bowel stoma after surgery to remove the colon tumor - 29% versus 67% in the stenting group (p<0.001) [57]. At the same time, it should be noted that the rate of severe complications was higher in stoma patients - 15.3% versus 5.8% in the stenting group, however, this did not affect overall and relapse-free survival, which was comparable between the groups [57]. Compared with primary colon resection, the rates of cumulative mortality and complications are comparable, however, in the group of patients with a stoma, an interintestinal anastomosis can be formed more often - in 89.3% versus 49.2% when the colon tumor is removed as the first stage of treatment. In 9.4% of cases, patients remain with a permanent stoma, while in the primary resection group this figure is 21.6% [54]. In case of bowel obstruction caused by a rectal tumor, it is advisable to avoid primary rectal resection according to Hartmann, since this significantly complicates the patient's subsequent rehabilitation. In addition, when the tumor is localized in the mid- or lower-ampullary rectum, especially in the case of locally advanced tumors, performing a resection intervention deprives the patient of the opportunity to receive neoadjuvant chemoradiotherapy, thereby undermining the principles of oncological radicality [58;59].

• In unstable patients with obstructive acute intestinal obstruction caused by a tumor or in case of technical difficulties in bringing out a loop colostomy, a parietal colostomy can be used as a decompression procedure [60].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: patients with obstructive acute intestinal obstruction caused by a tumor are not recommended to undergo parietal colostomy, including cecostomy, because it does not provide complete cessation of intestinal passage and adequate relief of complications of the tumor process. This operation can be justified only in a limited number of patients in critical condition when stenting or loop bowel stoma formation cannot be performed [60].

3.3.2.2 Colon resection

The most frequently performed radical surgical intervention for left-sided colon cancer complicated by acute intestinal obstruction is colon resection with end colostomy (Hartmann's procedure) [12]. When tumors are located in the right parts of the colon, operations with anastomosis formation are performed, and if colon resection without anastomosis creation is necessary, a single-barreled ileostomy is formed.

The advantage of such operations is the elimination of the probability of inter-intestinal anastomosis leakage, as well as tumor removal at the initial stage of treatment. However, it should be noted that resection interventions are associated with a high rate of postoperative mortality (9%) and postoperative complications, including those related to the intestinal stoma. Risk factors for a fatal outcome are advanced age (>70 years), high anesthetic risk (ASA 3), heart failure, and neurological disorders. Of importance is the low rate of reconstructive procedures — only 35% of patients subsequently manage to restore natural defecation [12]. It was shown that the average number of lymph nodes in the resected specimen after emergency interventions is lower than in elective surgery (8.7 vs 21) [61].

It should be noted that dozens of randomized trials and meta-analyses have been conducted on the choice of the optimal surgical treatment strategy for patients with acute intestinal obstruction. Pubmed analysis over the last 5 years for the query "large bowel obstruction" revealed 10 meta-analyses dedicated to the choice of the optimal primary surgery: stoma, stent, resection. Of these, a single study showed that primary decompression surgery, in particular stenting, had advantages over primary resection in terms of in-hospital 90-day mortality: 6.5% vs 8.1% (RR 0.65, P = 0.01) [62]. Identical results of overall 3- and 5-year survival were obtained when comparing stoma and stent with primary resection, except for a single meta-analysis where stoma and stent had advantages. The same study established higher 5-year disease-free survival when using a stoma and stent. Regarding 3-year disease-free survival, two meta-analyses established advantages of primary resection [63;64]. The stoma and stent groups had clear advantages in terms of complication rates and primary anastomosis formation, with a certain advantage of primary resection in terms of cumulative hospital stay duration. The number of removed lymph nodes was either equal [63] or favored the stoma and stent group [65].

Overall, compared to emergency surgery, self-expandable metal stents and stoma improve short-term surgical outcomes with comparable overall and disease-free survival. At the same time, stable patients may benefit from emergency resection, including with primary anastomosis, while unstable patients benefit from decompression via stoma, stent, or colorectal tube [66]. Analysis of surgical treatment results for acute intestinal obstruction according to the prospective national register of the Netherlands showed mortality after emergency resection ranging from 2.9% in patients <70 years to 32.2% in elderly high-risk patients. For frail elderly patients, postoperative mortality exceeding 30% necessitates the search for alternative treatment strategies [67].

• In stable patients with acute bowel obstruction due to colon cancer without perforation or peritonitis, if a qualified team of oncological surgeons or coloproctologists is available, and following additional evaluation in accordance with clinical guidelines for the treatment of colon and rectosigmoid cancer, tumor resection surgery may be performed [63;64].

GPP CLOE 1Level of Evidence - C (Level of Data Reliability - 1)

Comment: considering current data, resection procedures should be used only when performed by a qualified team of surgeons, oncologists, or coloproctologists, when conditions exist for a high-quality morphological examination of the resected tumor, and when alternative treatment options cannot be applied. Provision of a qualified surgical team is of particular importance in resection procedures that require compliance with oncological surgical principles. The scope of surgery in emergency resection without perforation or peritonitis should not differ from elective surgery, except for the creation of the intestinal anastomosis. If surgery cannot be performed according to established treatment principles for colon cancer in patients without perforation, resections should not be performed. The scope of surgery should be limited to a decompression stoma.

• When perforation, peritonitis, abscess formation, diastatic tears, and ischemic changes of the colon are detected, large bowel resection without anastomosis is recommended [12;27].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: there are two main mechanisms leading to bowel perforation and peritonitis in tumor-induced acute bowel obstruction. First, the formation of a bowel wall defect at the tumor site due to necrosis and breakdown of tumor tissue; second, a diastatic tear of the wall of the distended bowel located proximal to the obstruction site. The second option is often more severe and is associated with high mortality due to diffuse contamination of the abdominal cavity and rapid development of severe septic shock [68]. Overall, in this situation, every effort must be made to resect the affected bowel segment together with the tumor, but the treatment strategy must be balanced and take into account the severity of the patient's condition—unstable patients should undergo only those procedures they can tolerate, which usually corresponds to technically simple and rapidly performed interventions, such as a Hartmann procedure or a right hemicolectomy without anastomosis, with the formation of a single-barrel ileostomy; in case of diastatic perforation of the right colon in patients with left-sided colon cancer, a subtotal colectomy without anastomosis is performed [12;27].

• Surgery to remove a malignant large bowel tumor with the creation of an intestinal anastomosis in acute bowel obstruction is recommended to be performed only after resolution of acute bowel obstruction symptoms in stable patients without severe comorbidities, provided there is a qualified team of surgeons, oncologists, or coloproctologists, in accordance with the clinical guidelines for the treatment of patients with colon and rectal cancer [7;89;90].

GoR CLoE 5Grade of Recommendation - C (Level of Evidence - 5)

Comment: intestinal obstruction is associated with an increased risk of a potentially fatal complication—inter-intestinal anastomotic leakage. The incidence of anastomotic leakage in intestinal obstruction ranges from 11.2% to 14.3%, with mortality reaching 17.1% [69;70]. Anastomotic leakage most frequently occurs after subtotal colectomy (14%), left hemicolectomy (13%), and transverse colon resection (10.3%) [12]. Risk factors for an unfavorable prognosis in surgery involving anastomosis formation include patient age over 70 years, high anesthetic risk (ASA > 3), anemia (Hb < 75 g/L), chronic kidney disease (glomerular filtration rate (GFR) < 45 mL/min/1.73 m²), chronic heart failure, respiratory failure, and neurological deficit. In the presence of any of these risk factors, anastomosis formation should be abandoned in favor of resection without creating an inter-intestinal anastomosis [12;71]. A complicated postoperative course may be the reason for a delayed start of chemotherapy or its complete omission.

3.4 Palliative treatment of patients with acute obstructive intestinal obstruction

The main goal of treatment for patients with stage IV colorectal cancer and acute bowel obstruction is to increase the patient's life expectancy and improve their quality of life. Available treatment options include systemic corticosteroids and gastrointestinal motility stimulants, supportive care such as nasogastric intubation and parenteral nutrition, bowel stenting, and surgical interventions such as proximal stoma creation and bowel resection. However, overall survival remains low regardless of the treatment type. Consistently poor outcomes suggest that acute bowel obstruction in the setting of incurable colorectal cancer should be considered a pre-terminal event [72]. In such situations, an individualized multidisciplinary approach with enhanced patient involvement in choosing the treatment scope is preferred [73]. When signs of perforation, strangulation, and peritonitis are detected in patients with stage IV colorectal cancer, emergency surgery is required. Efforts should be made to perform the minimal possible scope of intervention, favoring the creation of a proximal stoma. If bowel perforation, ischemia, and abscess formation are detected, bowel resection should be performed.

In patients with disseminated colorectal cancer complicated by compensated bowel obstruction, palliative large bowel resection may be performed. The grounds for performing such surgery are the decision of a multidisciplinary oncological board. Currently, there is no convincing evidence regarding the benefit or harm of palliative bowel resection in patients with disseminated cancer. The results of existing studies are contradictory, and most studies are retrospective, meaning many important variables such as the number of metastases, their size, and target organ characteristics may not be accounted for, precluding the use of precise statistical processing methods [74]. The rationale for palliative resection is the expected improvement in the patient's quality of life and the provision of optimal conditions for chemotherapy.

Issues of pain control and nutritional support in palliative patients are not covered in these guidelines.

• In obstructive bowel obstruction caused by tumors in stage IV colorectal cancer patients with a short expected life expectancy, bowel stenting is recommended [75].

GoR BLoE 2Grade of recommendation - B (level of evidence - 2)

Comment: colonic stenting as part of palliative treatment of patients with obstructive acute intestinal obstruction can eliminate the need for formation of an intestinal stoma, which may potentially provide an acceptable quality of life for patients [53]. However, despite the high rate of technically successful stenting (in the presence of only one tumor-related obstruction) – from 90 to 100% of cases, and a shorter hospital stay compared to stoma formation [76], stenting is more often associated with early postoperative complications [44]. The recurrence rate of acute intestinal obstruction is higher in the group of patients who underwent stenting - 20.7% versus 9% in the surgical treatment group [75].

• In stage IV cancer patients where bowel stenting is impossible, multiple sites of bowel obstruction are present, or systemic anticancer drug therapy is administered, surgical intervention involving the creation of a proximal colostomy/ileostomy is recommended [77].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: the mainstay of treatment for patients with disseminated colorectal cancer is chemotherapy. Because the presence of a stent in the tumor channel in patients receiving long-term bevacizumab** is associated with a high risk of tumor perforation, other methods of large bowel decompression should be used [46]. Stoma formation is a relatively simple and accessible procedure that allows for rapid and reliable large bowel decompression [77].

4. Medical Rehabilitation and Sanatorium-Resort Treatment

• In patients undergoing laparotomy, epidural anesthesia based on local anesthetics and opioids is recommended for postoperative pain control [78].

GoR BLoE 3Grade of recommendation - B (level of evidence - 3)

Comment: the optimal analgesia regimen after major surgeries should provide an adequate level of pain relief, promote early mobilization, more active recovery of bowel function and nutrition, and cause no complications [78]. The preferred approach is multimodal analgesia combining regional anesthesia techniques and, whenever possible, opioid-sparing strategies to avoid side effects. The use of opioid analgesics is associated with patient drowsiness and adynamia, bowel paresis, and episodes of nausea and vomiting.

In open midline laparotomy, epidural analgesia is the optimal method of pain relief during the first 72 hours after surgery, contributing to an earlier recovery of bowel function and a reduction in complications [79;80]. The use of 0.2% ropivacaine** solution combined with fentanyl** provides optimal pain relief while minimizing the risk of motor block and hypotension due to sympathetic blockade [78;81]. To eliminate hypotension caused by sympathetic blockade, vasopressin and its analogues should be administered in the absence of hypovolemia. It is preferable to remove the epidural catheter 48–72 hours after surgery.

• After surgery and emergence from post-anesthetic depression, it is recommended to prescribe nutritional support in the form of oral nutrition, including tube feeding as a supplement; once normal intestinal peristalsis recovers, regular food intake can be resumed [82;83].

Level of Evidence CQuality of Evidence 2Strength of Recommendation - C (Level of Evidence - 2)

Comment: the use of enteral infusions of saline, monomer-saline and nutrient mixtures, as well as intestinal sorbents in the postoperative period contributes to a faster recovery of gastrointestinal function[84]. Supplemental oral nutrition (using special mixtures for convenience, including sipping) can increase total food intake, thereby achieving target nutritional goals [85;86].

• Removal of the urethral catheter is recommended after the patient is mobilized, preferably on the 2nd postoperative day [87].

Level of Evidence CQuality of Evidence 2Strength of Recommendation - C (Level of Evidence - 2)

Comment: bladder catheterization is used for precise diuresis monitoring, in case of urinary retention, and when the patient is unable to control pelvic functions. Prolonged presence of a urinary catheter increases the risk of urinary tract infection and hinders early mobilization. If the patient is able to control pelvic functions, removal of the urinary catheter is possible as early as 1–2 days after surgery [87]. A longer duration of urinary catheterization may be required in patients receiving epidural analgesia.

• Patients who have undergone surgery for acute intestinal obstruction are recommended early mobilization in the postoperative period [81,88].

GOM BLOE 3Grade of Recommendation - B (Level of Evidence - 3)

Comment: Prolonged bed rest increases the incidence of thromboembolic complications and respiratory disorders, reduces muscle strength, and increases the risk of hemodynamic instability. Patient activity is determined by both objective and subjective factors. Important elements include adequate pain relief, timely removal of drains and catheters. In addition, the patient needs to be reassured about the safety of physical activity after surgery and put at ease regarding the risk of suture dehiscence in the early postoperative period. Getting the patient out of bed starting from the 1st postoperative day and regular physical activity are associated with a decreased frequency of postoperative complications and a shorter hospital stay [88].

5. Prevention and Dispensary Observation

5.1 Prevention

Prevention of acute obstructive colon cancer is based on early diagnosis of colorectal cancer and should be carried out in accordance with the treatment guidelines for rectal and colon cancer [89; 90].

5.2 Dispensary Follow-up

• All patients who have undergone surgery for acute obstructive tumor-induced bowel obstruction are subject to follow-up monitoring by an oncologist or colorectal surgeon [91-93].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: following a radically performed bowel resection for colorectal cancer and adjuvant chemotherapy (if indicated), patients undergo follow-up monitoring aimed at detecting potential complications, diagnosing cancer recurrence, and discovering synchronous or metachronous neoplasms. An analysis of data from 18 large randomized trials totaling 20,898 patients showed that up to 80% of all cases of colon cancer recurrence develop within the first 3 years after resection [91], and up to 95% of all recurrences within 5 years after surgery [92].

For stage II–III patients who have undergone successful resection of a malignant colon tumor (in the absence of residual tumor), follow-up examinations may be recommended every 3–6 months for the first 2 years after surgery, and every 6 months thereafter up to 5 years. Colonoscopy should be scheduled 1 year postoperatively (or in 1–3 months if total colonoscopy was not performed during the preoperative workup). Endoscopic examination of the colon should be repeated annually for up to 3 years, and then every 5 years [93]. However, if an adenomatous/villous polyp or high-grade epithelial dysplasia is detected, colonoscopy should be repeated annually. More frequent endoscopic examinations may be recommended for young patients (under 50 years of age). Colonoscopy as part of follow-up surveillance is primarily necessary for the diagnosis of metachronous polyps and their subsequent removal, since patients with a history of colon cancer are at risk of developing a second primary cancer, especially within the first 2 years following surgery [94].

Computed tomography is recommended to detect potentially resectable metastases, predominantly in the lungs and liver. Consequently, CT scanning may not be used routinely in patients with asymptomatic generalized cancer who are not candidates for potentially radical surgical treatment. Computed tomography of the chest, abdomen, and pelvis should be performed every 6–12 months for up to 5 years in stage III disease and in stage II patients with a high risk of disease recurrence [95].

6. Organization of Medical Care

6.1 Indications for hospital admission

All patients with suspected bowel obstruction must be urgently hospitalized in a surgical inpatient facility. In cases of acute bowel obstruction caused by a colonic tumor, care is emergency in nature. The timing of admission for such patients can determine the outcome of the disease. Delaying the initiation of treatment or violating the timeline of treatment stages leads to a decrease in overall and disease-free survival rates in these patients and worsens the prognosis for a specific individual.

Diagnostic measures at the stage of diagnosis should be carried out in a surgical inpatient setting. The working group recommends that elective surgery, drug-based anti-tumor therapy, and radiation therapy be performed in specialized inpatient departments (oncology, coloproctology).

All patients scheduled for a surgical procedure for colon cancer must give informed consent. This implies that the patient has been provided with information about the potential benefits and hypothetical risks of treatment, as well as the availability of any alternative treatment methods. Whenever possible, informed consent should be obtained directly by the operating surgeon. In accordance with Federal Law No. 323-FZ of the Russian Federation dated November 21, 2011, "On the Basics of Protecting the Health of Citizens in the Russian Federation," obtaining written informed consent is a mandatory and necessary procedure that reflects compliance with the legal and ethical rights of a person to make independent decisions regarding their health. The conditions for obtaining informed consent are the patient's ability to make deliberate decisions regarding treatment measures and the accessible provision of all information necessary for decision-making. Key issues include: the benefits and risks of the proposed treatment, the planned scope of treatment, and the consequences of refusing treatment.

• Surgeries to remove a colon tumor in acute bowel obstruction are recommended to be performed in a surgical, coloproctological, or oncological department by a specialist experienced in performing oncological colorectal surgeries [69].

GCP CLOE 4Grade of Recommendation — C (Level of Evidence — 4)

Comment: lack of physician specialization in colorectal surgery is an adverse prognostic factor [69]. It has been demonstrated that the overall rate of postoperative complications and postoperative mortality is higher when surgery is performed by a surgeon lacking specialized training. The rate of anastomotic leakage in general surgical inpatient facilities is twice as high as in specialized medical institutions (21.3% vs. 10.3%) [96]. In patients operated on in general surgical departments, the number of lymph nodes examined in the specimen fails to meet the required standard of 12 or more in 98.3% of cases [96]. Overall and disease-free survival are statistically significantly lower in the group of patients operated on in non-specialized hospitals. In stage III patients operated on after the resolution of acute intestinal obstruction in oncological departments, the 5-year overall survival rate is 50%, whereas among those operated on in the presence of acute intestinal obstruction in non-specialized hospitals, it is 28% ($p=0.02$) [97].

6.2 Indications for patient discharge from a medical organization

Upon hospitalization for acute intestinal obstruction, the timing of patient discharge from a medical organization depends on the scope of medical care provided, the nature of the surgical intervention, and the course of the postoperative period. Discharge in an uncomplicated postoperative course is performed upon improvement of the patient's condition, restoration of gastrointestinal tract function, relief of endotoxemia, and normalization of red blood cell parameters. Discharge from a non-specialized surgical department, with mandatory referral of the patient to an oncological or coloproctological hospital, is performed once the symptoms of acute intestinal obstruction are relieved via bowel stenting or the formation of a proximal loop stoma.

In situations where acute intestinal obstruction has resolved with conservative treatment, the patient is transferred to a specialized oncological or coloproctological hospital (department) to prevent obstruction recurrence.

7. Additional Information

Factors negatively affecting treatment outcomes:

Bowel perforation

Non-radical tumor removal

Incomplete pathomorphological description of the resected tumor specimen

Refusal of adjuvant chemotherapy when indicated.

Criteria for Evaluating the Quality of Medical Care

When performing resection procedures for complicated colorectal cancer,

When performing resection procedures for colorectal cancer complicated by acute intestinal obstruction, the quality of medical care provided should be assessed in accordance with the clinical guidelines for the treatment of colon and rectal cancer. [89;90]

References

Appendix A1. Working Group Composition

All working group members are members of the Association of Coloproctologists of Russia, the Association of Oncologists of Russia, and the Russian Society of Surgeons. There is no conflict of interest.

Appendix A2. Methodology for Developing Clinical Guidelines

Target audience of the clinical guidelines:

1. Coloproctologists.

2. Surgeons.

3. Oncologists.

4. General practitioners.

5. General practitioners (family physicians).

6. Endoscopists.

7. Nursing staff.

8. Medical students, residents, postgraduate students.

Table 1. Rating scale for levels of evidence (LoE) for diagnostic methods (diagnostic interventions).

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

Table 3. Scale for assessing the recommendation grades (RG) for prevention, diagnostic, treatment, and rehabilitation methods (preventive, diagnostic, therapeutic, and rehabilitative interventions).

Procedure for updating clinical guidelines.

The guideline revision mechanism provides for their systematic updating at least once every three years, as well as upon the emergence of new evidence-based medicine data regarding 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

These clinical guidelines were developed taking into account the following regulatory legal documents:

• Clause 3 of Article 37 of Federal Law of the Russian Federation No. 323-FZ dated November 21, 2011, "On the Fundamentals of Protecting the Health of Citizens in the Russian Federation" (as amended, effective January 11, 2023);

• 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. 206n dated April 2, 2010 (as amended on February 21, 2020), "On Approval of the Procedure for Providing Medical Care to the Population with Colorectal, Anal Canal, and Perineal Diseases in Coloproctology";

• Order of the Ministry of Health of the Russian Federation No. 116n dated February 19, 2021, "On Approval of the Procedure for Providing Medical Care to Adults with Oncological Diseases" (as amended by Order of the Ministry of Health of the Russian Federation No. 21n dated January 24, 2022);

• Order of the Ministry of Health of the Russian Federation No. 922n dated November 15, 2012, "On Approval of the Procedure for Providing Medical Care to Adults in the Profile of 'Surgery'" (as amended on February 21, 2020)

Appendix B. Physician Action Algorithms

Appendix C. Patient Information

Disease information.

Intestinal obstruction is a disruption of the passage of contents through the intestine caused by luminal occlusion, compression, spasm, hemodynamic or innervation disorders. Intestinal obstruction manifests as cramping abdominal pain, nausea, vomiting, constipation, and failure to pass gas. Conservative management is possible for certain types of intestinal obstruction; in other cases, surgical intervention is performed with the aim of restoring the passage of intestinal contents or diverting them externally, or resecting the affected bowel segment. If intestinal obstruction is suspected, medical attention should be sought immediately. Before a doctor's examination, it is strictly forbidden to administer enemas, give analgesics, take laxatives, or perform gastric lavage.

Information required in the postoperative period.

Intestinal obstruction can be partial or complete. In the former case, acute conditions requiring immediate hospitalization typically do not occur, and after thorough examination, optimal treatment options can be offered to the patient. Clinically, this manifests mainly as delayed stool and gas passage. Complete occlusion of the intestinal lumen leads to acute intestinal obstruction. In this case, severe cramping abdominal pain, nausea, and repeated vomiting join the delayed stool and gas passage. Acute intestinal obstruction is a life-threatening condition requiring urgent medical care in a surgical inpatient setting. With this course of events, several courses of action are possible. The first option is surgery to remove the affected segment of the intestine along with the tumor. The second is the removal of the tumor and creation of an intestinal stoma in a single operation. Stoma creation refers to a surgical procedure bringing a segment of the intestine out onto the anterior abdominal wall. An ostomy bag will be required to collect intestinal contents. The third option is staged treatment: a stoma is created first, and the tumor is removed subsequently. Another option is the placement of a stent to dilate the intestinal lumen, followed by tumor removal as a second stage. The prognosis for acute intestinal obstruction of tumor origin directly depends on the timing of seeking medical care—the earlier, the more favorable.

As a rule, patients with acute intestinal obstruction caused by a colorectal tumor learn about their disease either shortly before emergency surgery or already after it. To determine further treatment tactics for malignant neoplasms, all patients must consult an oncologist and undergo a specific list of diagnostic procedures. These procedures include a physical examination, computed tomography, total colonoscopy, and blood tumor marker levels. CT examination allows for proper staging of the disease and detection of potential metastases. Scanning of the chest, abdomen, and pelvis is recommended. Colonoscopy is indicated to examine all parts of the large intestine, including those not previously visualized due to intestinal obstruction. It can be performed 1–3 months after surgery. Tumor marker levels are also an integral part of the diagnostic program.

Patients with an intestinal stoma need to consult a healthcare professional specializing in ostomy care. It is important to modify physical activity habits to avoid damaging the stoma during daily activities, and to learn how to care for it. Subsequently, in a number of cases, reconstructive surgery to restore intestinal continuity—stoma closure—may be performed.

In the postoperative period, maintaining a healthy lifestyle is important. The main aspects of a healthy lifestyle are a balanced diet, physical exercise, and smoking cessation.

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

No.