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Meckel's diverticulitis

Meckel's diverticulitis is the inflammation of Meckel's diverticulum, which is the most common congenital structural abnormality of the gastrointestinal tract 3. Despite this, it is an uncommon causes of acute abdomen, and is often not correctly diagnosed pre-operatively. 

This article focuses on Meckel's diverticulitis. For a general discussion of the un-inflamed diverticulum, please refer to the article on Meckel's diverticulum

Epidemiology

Meckel's diverticulum is seen in approximately 2% of adult population, predominantly in males1.

Clinical features

Patients usually present with acute pain in right lower quadrant. Painless rectal bleeding is also frequent.

Pathology

A number of mechanisms are recognised as precipitants of diverticulitis. Meckel's diverticulitis can occur due to bacterial infection, which can go on occasionally to gangrene. This is similar in pathogenesis to acute appendicitis or colonic diverticulitis

Peptic ulceration due to acid secretion from gastric mucosa(see Meckel's diverticulum) or diverticular torsion are also encountered. 

Radiological features

Ultrasound

Meckel's diverticula are usually seen as tubular incompressible blind ending hypoechoic structure with irregular margins. Occasionally it may also be seen as a cyst, raising a different differential diagnosis of intestinal duplication which however is said to have regular margins 2 . Doppler may reveal anomalous vessels and signs of inflammation along the diverticulum.

CT

CT is the main modality employed in imaging patients with acute abdominal pain and signs of inflammation. 

Meckel's diverticula are round or tubular fluid/air filled structures communicating with small bowel with a wall-to-wall diameter of 1.5-6 cm. Mural wall thickening and enhancement is seen with surrounding inflammatory changes in the adjacent fat as well as small reactive mesenteric lymph nodes. Wall enhancement will be absent in gangrenous Meckel's diverticulum.

Rarely, an enterolith can also be visualized within the diverticulum. As is the case with appendicitis, it is said that contrast opacification of diverticula is suggestive of inflammation. 

small bowel obstruction may also be present and in many cases this is the only pre-operative finding.  

Reporting checklist

Identification of Meckel's diverticulitis requires not only familiarity with the condition but also careful examination of the small bowel. If an inflammed diverticulum is identified a number of features should be sought and commented upon, including:

  • diverticulum
    • estimate the distance from the ileocaecal junction
    • size/length of diverticulum
    • location relative to the abdominal surface anatomy
    • enhancement/non-enhancement of wall (non-enhancement suggests gangrene and impending rupture)
  • appendix: look for signs of inflammation
  • free intra-abdominal gas
  • intra-abdominal fluid/abscess formation
  • small bowel obstruction
Small bowel follow-through or CT enteroclysis

They can be used to diagnose morphological Meckel's diverticulum, however sensitivity depends on contrast opacification, and has no role in cases of suspected acute diverticulitis.

Pertechtenate scan (nuclear medicine)

Ectopic gastric mucosa, if present, can be picked up on this scan, but again does not usually play a role in acute presentation. 

Differential diagnosis

Clinically the differential diagnosis is broad, and unless a Meckel's diverticulum is known to be present, Meckel's diverticulitis is usually not specifically suspected. 

Imaging can also be challenging, with the most common differentials including:

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