Meckel’s diverticulum

Section: Small bowel Curriculum: Curriculum, page 60

Definition

• Outpouching on antimesenteric aspect of ileum
• True diverticulum, containing all layers of the bowel wall
• 40-60cm (2ft) from ileocaecal valve
• May have various forms:
  • Small bump to long projection
  • May communicate with umbilicus via small fibrous strand
    • Rarely patent fistula
  • Usually wide mouthed diverticulum
    • 5cm (2inches) long with diameter of 2cm

Incidence

• M = F
• 2%

Rule of 2’s

• 2% of population
• 2% symptomatic
  • Children are usually < 2
• Affects males twice as often as females
• Located 2 feet from ileocaecal valve
• 2 inches long or less
• 2 types of mucosal lining (gastric and pancreatic)

Aetiology

• Results from incomplete closure of Vitelline Duct connecting midgut to yolk sac
  • See Gastrointestinal embryology
  • Duct normally involutes between 5th-6th weeks of gestation
• Cells lining duct are pluripotent
  • Therefore can find heterotopic tissue
    • Gastric most common – 50%
    • Pancreatic 5%
    • Colonic mucosa is rare

Clinical Presentation

• Majority incidental finding
• GI bleeding
  • 25-50% of complications
  • Commonly in children < 2
  • Usually due to gastric mucosa secreting acid and ulceration of mesenteric aspect
  • Acute GI bleed
  • IDA
  • Recurrent episodes
• Obstruction
  • Volvulus around fibrous band
  • Intussusception – Diverticulum invaginates and then intussuscepts
  • Incarceration into inguinal hernia (Littre’s Hernia)
• Diverticulitis
  • 10-20% complications
  • More common in adults
  • Presents similar to appendicitis
• Neoplasm
  • Benign – Leiomyoma, Angioma, Lipoma
  • Malignant – Adenocarcinoma, NET, Sarcoma

Diagnosis

• Meckel’s scan
  • Oral delivered Na 99Tc – pertechnetate scintigraphy
    • 99-Tc pertechnetate is preferentially taken up by mucus secreting cells of gastric mucosa in the ectopic gastric tissue
      • Found in 50% of diverticulum and the majority of those that bleed
      • Less accurate in adults as reduced prevalence of gastric mucosa
• May be augmented by
  • Pentagastrin – increases metabolism of gastric mucosal cells
  • Glucagon – Reduces peristalsis and prolongs uptake of Tc-99
  • H2 Receptor Antagonists
    • Decreases peptic acid secretion (but not uptake of Tc-99) therefore reduces expulsion of isotope after uptake
• Angiography – CT-A in acute haemorrhage
• Diagnostic Laparoscopy

Management

• Non-operative for asymptomatic Meckel’s
• Incidental finding during operation
• In children
  • Generally resect due to increased life-long risk of complications
• In adults
  • < 50 likelihood of becoming symptomatic ~ 2-6%
    • Complication rate ~ 6%
    • General consensus is to leave alone unless suspicious features
      • Palpable abnormality

      • 2cm

      • Male < 50 years
      • Anyone under 18
      • Presence of ectopic tissue in diverticulum
  • If > 50 and normal appearing, leave alone
• Operative
  • Formal resection for symptomatic Meckel’s
    • Don’t just staple off as heterotrophic mucosa can travel into lumen
    • As need to remove the ulcer
  • If asymptomatic
    • Long
      • Can do a diverticulectomy
    • Short and wide
      • Should do a formal resection