Overview
Meckel's Diverticulum
1. Clinical Overview
Summary
Meckel's Diverticulum is the most common congenital anomaly of the gastrointestinal tract. It is a true diverticulum (containing all three layers of the bowel wall: Mucosa, Submucosa, Muscularis) arising from the anti-mesenteric border of the ileum. It represents a remnant of the Vitellointestinal (Omphalomesenteric) Duct, which normally connects the fetal midgut to the yolk sac and obliterates by week 7-8 of gestation. Most are asymptomatic. Complications occur due to the presence of ectopic tissue (most commonly Gastric mucosa, which secretes acid causing ulceration and bleeding) or lead to intestinal obstruction or inflammation (Diverticulitis). [1,2]
Clinical Pearls
The Rule of 2s: The classic teaching mnemonic for Meckel's Diverticulum.
- 2% of the population.
- 2 feet (60cm) from the Ileocaecal Valve.
- 2 inches (5cm) long.
- 2 types of ectopic tissue (Gastric most common, then Pancreatic).
- Symptomatic usually by age 2 years.
- 2:1 Male to Female ratio for complications.
Painless Rectal Bleeding: The classic presentation in young children is painless, brick-red rectal bleeding (altered blood due to gastric acid action on small bowel mucosa / mixed with stool). Think Meckel's in any child less than 5 with significant lower GI bleed.
"Appendicitis on the Wrong Side": Meckel's Diverticulitis can mimic appendicitis (central then localised RIF pain), but may be more periumbilical or left-sided.
2. Epidemiology
Demographics
- Prevalence: ~2% of the general population (autopsy studies).
- Sex: Equal prevalence, but symptomatic complications are 2-3x more common in Males.
- Age of Presentation: Most symptomatic cases present in childhood (less than 10 years), with peak less than 2 years.
- Asymptomatic: The vast majority remain asymptomatic throughout life. Lifetime risk of complications is ~4-6%.
3. Pathophysiology
Embryology
- Week 4-5 Gestation: The Vitellointestinal Duct connects the developing midgut to the yolk sac.
- Week 7-8: The duct normally obliterates completely.
- Failure of Obliteration: Results in various remnants:
- Meckel's Diverticulum: Most common. Complete failure at ileal end.
- Fibrous Band: Connects diverticulum tip to umbilicus. Causes obstruction.
- Umbilical Sinus/Polyp: Remnant at umbilical end.
- Vitelline Cyst: Persistence in middle of duct (Omphalomesenteric cyst).
- Patent Vitellointestinal Duct (Umbilical Fistula): Rare. Faecal discharge from umbilicus.
Structure
- True Diverticulum: Contains all bowel wall layers.
- Location: Anti-mesenteric border of the terminal Ileum (has its own blood supply - Vitelline artery remnant).
- Ectopic Mucosa: ~50% contain ectopic tissue. Gastric mucosa (most common, ~80%), Pancreatic tissue (5-10%), Duodenal, Colonic.
Mechanism of Complications
- Bleeding (Most Common in Children): Ectopic Gastric mucosa secretes Acid. This causes peptic ulceration at the junction between ectopic and normal ileal mucosa.
- Obstruction: Fibrous band (Meckel's to Umbilicus) acts as a fulcrum for Volvulus. Internal herniation can occur. Intussusception (Meckel's acts as lead point).
- Diverticulitis (Inflammation): Mimics appendicitis.
- Perforation: From ulceration or diverticulitis.
4. Differential Diagnosis (Lower GI Bleeding in Children)
| Condition | Key Features |
|---|---|
| Intussusception | 6 months - 2 years. Colicky pain, "Redcurrant jelly" stool (late), Sausage-shaped mass. |
| Juvenile Polyps | Painless, bright red blood on surface of stool. Usually rectosigmoid. |
| Infectious Colitis | Diarrhoea, Fever, Blood mixed with stool. Stool cultures positive. |
| Anal Fissure | Bright red blood on wiping/surface. Pain on defecation. |
| Inflammatory Bowel Disease (IBD) | Older children. Bloody diarrhoea, Abdominal pain, Weight loss, Growth failure. |
| Henoch-Schönlein Purpura (HSP) GI Involvement | Purpuric rash, Arthralgia, Abdominal pain, GI bleeding. |
5. Clinical Presentation
Bleeding (Most Common Presentation less than 5 Years)
Intestinal Obstruction
Diverticulitis (Meckel's Inflammation)
Perforation
Painless Rectal Bleeding
Brick-red or maroon blood. May be massive.
Anaemia
In chronic or occult bleeding.
Note
The blood is often described as "currant jelly"-like or maroon rather than bright red, as the acid-induced ulceration is in the small bowel.
6. Investigations
Meckel's (Technetium-99m Pertechnetate) Scan - "Meckel's Scan"
- Principle: Technetium-99m Pertechnetate is taken up by Gastric mucosa (wherever it is).
- Positive Scan: Ectopic uptake in the RLQ (distinct from stomach and bladder).
- Sensitivity: ~85% for symptomatic Meckel's with gastric mucosa. Lower if no ectopic gastric tissue.
- Enhancers: Pentagastrin, H2-blockers, Glucagon can increase sensitivity.
Other Investigations
- FBC: Anaemia.
- Group & Save / Crossmatch: If significant bleeding.
- Abdominal X-Ray: May show small bowel obstruction.
- CT Abdomen: May show inflamed diverticulum or obstruction. Less reliable for uncomplicated Meckel's.
- Capsule Endoscopy / Enteroscopy: For occult GI bleeding if Meckel's scan negative.
- Laparoscopy / Laparotomy: Often diagnostic and therapeutic.
7. Management
Management Algorithm
SUSPECTED MECKEL'S
(Painless Rectal Bleed in Child < 5
OR Atypical Appendicitis / Obstruction)
↓
RESUSCITATE IF BLEEDING
(IV Access, Fluids, Transfuse PRN)
↓
MECKEL'S SCAN (Tc-99m)
(If stable and not obstructed)
┌────────┴────────┐
POSITIVE NEGATIVE (but high suspicion)
↓ ↓
SURGERY CONSIDER:
(Diverticulectomy - Laparoscopy
or Segmental - Capsule Endoscopy
Resection) - CT Angiography
↓
TREAT CAUSE
↓
IF OBSTRUCTION / PERITONITIS
-> EMERGENCY LAPAROTOMY
Symptomatic Meckel's (Bleeding, Obstruction, Diverticulitis)
- Surgical Resection: Definitive treatment.
- Diverticulectomy: Simple excision of diverticulum if inflammation/ulceration at base is minimal.
- Small Bowel Resection + Primary Anastomosis: If ulceration extends to adjacent ileum or if diverticulum is broad-based.
- Laparoscopic Approach: Increasingly common.
Incidentally Discovered Meckel's (Asymptomatic)
- Controversial: Risk of lifetime complication (~4%) vs Risk of surgery.
- General Consensus: Resect if:
- less than 50 years old (higher lifetime risk).
- Palpable abnormality (e.g., thickening at tip suggesting ectopic tissue).
- Fibrous band present.
- Found during surgery for another reason in a young patient.
- Leave if elderly and no concerning features.
Emergency
- GI Bleed: Resuscitate, Transfuse, Urgent Surgery.
- Obstruction / Peritonitis: Emergency Laparotomy.
8. Complications
Of Meckel's Diverticulum (If Untreated)
- Haemorrhage: Can be massive and life-threatening.
- Intestinal Obstruction: Volvulus, Intussusception, Internal Hernia.
- Diverticulitis / Perforation / Peritonitis.
- Neoplasia (Rare): Carcinoid tumour, Adenocarcinoma, GIST.
Post-Operative
- Anastomotic Leak (Rare).
- Adhesional Obstruction.
9. Prognosis and Outcomes
- Symptomatic Meckel's: Excellent prognosis after resection.
- Incidental Meckel's (Untouched): ~4-6% lifetime risk of complication.
- Mortality: Low overall, but can be significant if diagnosis delayed in large bleed or perforation.
10. Evidence and Guidelines
Key Guidelines
- No specific major international guidelines. Management based on surgical consensus and paediatric surgical textbooks.
Landmark Evidence
- Soltero MJ & Bill AH (1976): Classic epidemiological study defining the "Rule of 2s" and lifetime risk of complications.
- Yahchouchy EK (2001): Large review of incidental Meckel's management.
11. Patient and Layperson Explanation
What is Meckel's Diverticulum?
It's a small pouch sticking out from the lower part of the small intestine (ileum). It's something you're born with, left over from before you were born.
Is everyone born with it?
Only about 2 in 100 people have it. Most never know because it causes no problems.
Why does it sometimes cause trouble?
Sometimes the pouch contains tissue that normally belongs in the stomach. This tissue produces acid, which can eat into the surrounding bowel and cause bleeding. Other times, the pouch can twist or cause a blockage.
What are the symptoms?
- Bleeding from the bottom: Usually painless, dark red blood, in a young child.
- Tummy pain and vomiting: If there's a blockage.
- Pain like appendicitis: If it becomes inflamed.
How is it treated?
If it's causing problems, an operation is done to remove the pouch. This usually cures the problem completely.
12. References
Primary Sources
- Soltero MJ, Bill AH. The natural history of Meckel's Diverticulum and its relation to incidental removal. A study of 202 cases of diseased Meckel's Diverticulum found in King County, Washington, over a fifteen year period. Am J Surg. 1976.
- Elsayes KM, et al. Meckel diverticulum: multimodality imaging. AJR Am J Roentgenol. 2007.
13. Examination Focus
Common Exam Questions
- Mnemonic: "Rule of 2s?"
- Answer: 2% population, 2 feet from Ileocaecal valve, 2 inches long, 2 types ectopic tissue, Age less than 2.
- Investigation: "How is Meckel's diagnosed?"
- Answer: Meckel's Scan (Technetium-99m Pertechnetate) – detects ectopic Gastric mucosa.
- Embryology: "What structure does it arise from?"
- Answer: Vitellointestinal (Omphalomesenteric) Duct.
- Presentation: "Classic presentation in a 2-year-old?"
- Answer: Painless Rectal Bleeding (brick-red/maroon blood).
Viva Points
- True vs False Diverticulum: True contains all 3 layers (Meckel's, Zenker's Pharyngeal). False only Mucosa/Submucosa (Colonic diverticula).
- Why Ulceration at Junction?: Acid from ectopic gastric mucosa damages the adjacent normal ileal mucosa, not the gastric tissue itself (which is acid-resistant).
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.