Ultrasound diagnostics and management in pyloric stenosis
The key and most reliable criterion in the diagnostic imaging of hypertrophic pyloric stenosis is the transverse thickness of the pyloric muscle.
In clinical practice, borderline abnormal values during ultrasound are frequently encountered. They must be evaluated exclusively in conjunction with the transverse thickness. This parameter may vary depending on the child's birth weight and age; however, it has been proven that in true HPS, the transverse diameter of the pyloric muscle strictly exceeds 3 mm. This rule applies regardless of the patient's anthropometric data.
If measurement results are questionable or the clinical presentation (especially early onset of symptoms or prematurity) strongly suggests pathology, a repeat ultrasound examination is indicated. The radical treatment method for confirmed pyloric stenosis is surgical intervention — laparoscopic pyloromyotomy.
Omphalomesenteric (vitelline) duct remnants
Embryologically, the vitelline duct connects the midgut (midgut) to the extraembryonic yolk sac. Normally, its complete obliteration (involution) occurs in the middle of the first trimester of pregnancy. If this does not happen, persistence of the duct leads to a spectrum of congenital anomalies.
Statistically, symptomatic forms of such malformations are more frequently recorded in boys. About 60% of all clinical manifestations present before the age of 10 years.
Main anomaly variants:
- Meckel's diverticulum (Meckel diverticulum) — occurs most frequently.
- Umbilicoileal fistula (umbilicoileal fistula).
- Umbilical sinus (umbilical sinus) and umbilical cyst (umbilical cyst).
- Fibrous cord extending from the ileum to the umbilicus. This is the most common cause of small bowel obstruction (ileus) in children and adolescents who were previously completely healthy.
- Fully patent duct. It is rare, but presents vividly in the neonatal period: feces discharge from the umbilicus, or ileal prolapse occurs directly onto the anterior abdominal wall.
Detailed guide to Meckel's diverticulum
Meckel's diverticulum is the most common type of vitelline duct remnant, detected in 2–4% of the general population.
Anatomically, it is located on the antimesenteric border of the ileum (an important distinction from enteric duplication cysts, which grow on the mesenteric border). The usual distance is within 60 cm from the ileocecal valve. The wall of the diverticulum is complete and includes all layers of the intestinal tube. The dimensions of the formation can vary; if the length exceeds 5 cm, the diverticulum is classified as "giant". Foci of ectopic gastric mucosa and/or pancreatic tissue are often found inside.
Clinical manifestations:
- Melena. Occurs due to bleeding originating from a peptic ulcer (often against the background of ectopic mucosa).
- Intestinal obstruction (ileus). Develops as a result of intestinal intussusception (intussusception) or volvulus (volvulus) of loops around the diverticulum itself.
- Littre's hernia (Littre hernia). A specific condition in which Meckel's diverticulum becomes incarcerated in an inguinal hernia.
- Peritonitis / acute abdominal pain. A consequence of inflammation (diverticulitis) or wall perforation.
Establishing an accurate diagnosis before surgery is extremely difficult. Diagnostic imaging methods are chosen strictly individually, based on leading symptoms (e.g., searching for ectopic mucosa in case of bleeding).
Radiological patterns of gastric volvulus
Analysis of the radiological picture makes it possible to differentiate two main types of gastric volvulus.
Organoaxial volvulus (Organoaxial Torsion) During fluoroscopy with a contrast agent, the inverted position of the greater curvature of the stomach is visualized. The antrum is displaced in a caudal direction. Interestingly, the antrum itself and the pylorus may retain their normal anatomical position.
Mesenteroaxial volvulus (Mesenteroaxial Gastric Volvulus)
- On a plain radiograph, the classic "double bubble" sign (double bubble) is determined, located above the fluid-filled stomach. The uppermost of these bubbles corresponds to the antrum.
- During fluoroscopy, abnormal approximation of the pylorus and the gastroesophageal junction (GEJ) is recorded. In this case, the GEJ is displaced — it is located inferior and to the right of the pylorus. Placing a nasogastric tube helps to more accurately localize the esophagus and GEJ on the images.
Briefly: answers to topical questions
What diagnostic imaging methods are used to detect ectopic mucosa in Meckel's diverticulum?
Radioisotope scanning is used to detect ectopic gastric mucosa in Meckel's diverticulum.
- 99mTc-pertechnetate scintigraphy (99mTc-pertechnetate scintigraphy) is a method with high sensitivity and specificity for detecting bleeding diverticula.
The scintigram shows pathological accumulation of the isotope in Meckel's diverticulum along with its physiological accumulation in the stomach. The method is informative even in children without a prior history of rectal bleeding.
What causes hypertrophic pyloric stenosis in children?
- Heredity: having a first-degree relative with this pathology increases the risk of development by 5 times.
- Morphological changes: hypertrophy and hyperplasia of the circular muscles of the pylorus with some involvement of the longitudinal muscles, as well as hypertrophy of the muscular layer and mucosa.
- These changes lead to the formation of an elongated and narrowed pyloric channel, which is unable to relax, causing gastric outlet obstruction.
Class and exam questions
Which ultrasound criterion is considered the most reliable in diagnosing hypertrophic pyloric stenosis?
The most reliable criterion is the transverse thickness of the pyloric muscle. In true pathology, its transverse diameter exceeds 3 mm regardless of the child's weight and age.
What is the main anatomical difference between Meckel's diverticulum and enteric duplication cysts?
Meckel's diverticulum is always located on the antimesenteric border of the ileum, whereas enteric duplication cysts form on its mesenteric border.
What is Littre's hernia?
Littre's hernia is a specific type of incarceration in which Meckel's diverticulum enters and becomes trapped in the hernial sac of an inguinal hernia.
How does mesenteroaxial gastric volvulus appear on a plain radiograph?
It is characterized by the "double bubble" sign above the fluid-filled stomach, where the upper bubble represents the displaced antrum.
What else to study on this topic
- Methodology of neonatal gastric ultrasound
- Embryogenesis of the midgut and yolk sac
- Histological structure of the intestinal tube walls
- Pathophysiology of intestinal intussusception in children
- Technique of laparoscopic pyloromyotomy
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