Meckel’s diverticulum typically presents in children with painless rectal bleeding, and appears as a small outpouching on the antimesenteric border of the ileum and may contain ectopic gastric or pancreatic tissue.
Description
Meckel’s diverticulum is the most common congenital malformation of the gastrointestinal tract and the most common true diverticulum. It results from the incomplete obliteration of the omphalomesenteric (vitelline) duct, which connects yolk sac with gut lumen. It is a true diverticulum, containing all three layers of the bowel wall – mucosa, submucosa and muscularis propia. It is located on the antimesenteric border of the ileum, usually within 2 feet of the ileocecal valve.
Pathogenesis
The pathogenesis of Meckel’s diverticulum is related to the failure of the omphalomesenteric duct to completely involute during embryonic development. This duct normally connects the yolk sac to the midgut lumen, and its persistence leads to the formation of the diverticulum.
Subtypes
- Symptomatic: Exhibiting complications like bleeding, obstruction, or inflammation.
- Asymptomatic: Most cases are asymptomatic and incidentally found.
Epidemiology, Risk Factors & Associations
- Occurs in about 2% of the population.
- More common in males than females.
- Complications more likely in children than adults.
Clinical Features
- Painless rectal bleeding (most common in children).
- Abdominal pain, vomiting, and signs of intestinal obstruction.
- Can mimic symptoms of appendicitis.
Rule of 2’s:
- 2% prevalence
- 2:1 male-to-female ratio
- 2 inches long
- 2 feet from the ileocecal valve
- 2 types of ectopic tissue
- 2 years at presentation
- 2% develop complications
Complications
- Intestinal obstruction due to intussusception or volvulus.
- Haemorrhage from ectopic gastric mucosa.
- Peptic ulceration
- Inflammation leading to Meckel’s diverticulitis.
- Perforation and peritonitis.
- Risk of neoplasms (e.g., carcinoid tumors) is rare.
Pathological Features
Histopathology
- Macroscopic: A small pouch-like structure on the ileum.
- Microscopic: Ectopic gastric or pancreatic tissue in about 50% of cases. Other tissue includes duodenal/jejunal mucosa and Brunner glands.
Serology
- Not specific for Meckel’s diverticulum.
Biochemistry
- Not relevant for diagnosis.
Radiological Features
General Features
- Small outpouching on the antimesenteric border of the ileum.
- May show signs of inflammation, obstruction, or bleeding.
XR
- May show signs of obstruction or perforation.
CT
- Can identify diverticulum, signs of inflammation or complications like obstruction.
MRI
- Not routinely used for diagnosis.
US
- Can sometimes visualise the diverticulum, particularly in cases of complications.
NM
- Technetium-99m pertechnetate scintigraphy (Meckel’s scan): Highly sensitive for detecting ectopic gastric mucosa within the diverticulum.
Grading and Staging
No specific grading or staging system for Meckel’s diverticulum.
Diagnosis
Diagnosis is often incidental during imaging or surgery for other conditions. Technetium-99m pertechnetate scintigraphy (Meckel’s scan) is specific for detecting ectopic gastric mucosa. CT and ultrasound can be helpful in identifying complications.
Differential Diagnosis
- Appendicitis: Similar presentation with right lower quadrant pain.
- Intussusception: Sudden onset abdominal pain, “currant jelly” stool.
- Crohn’s Disease: Chronic abdominal pain, diarrhea, systemic symptoms.
- Gastroenteritis: Diarrhoea, vomiting, abdominal pain.
Management
Asymptomatic Meckel’s diverticulum usually requires no treatment. Symptomatic cases or those with complications are managed surgically, typically by diverticulectomy or segmental bowel resection.