Critical Care Medicine

Gastrointestinal Emergencies: Meckel's Diverticulum

Gastrointestinal Emergencies: Meckel's Diverticulum

Also known as: Omphalomesenteric Duct Remnant

1. Description of the problem

The omphalomesenteric duct typically involutes, however, if it does not there is often a persistent connection to the ileum which is termed a Meckel's diverticulum. A Meckel's diverticulum is often asymptomatic, however, if gastric mucosa is present it can cause severe painless bleeding.

The Rule of Two is often used to describe Meckel's diverticulum as it occurs in approximately 2% of the population, if found 2 feet from the ileocecal valve, is 2 inches long, and is found in a 2:1 ratio of male to female.

Clinical features

Painless rectal bleeding

Key management points

  • Fluid resuscitation

  • Meckel's scan

  • Surgical correction

2. Emergency Management

  1. Stabilize patient - painless rectal bleeding is often profuse and requires initial stabilization with IV fluids and occasionally blood products.

  2. Abdominal X-ray - an abdominal X-ray is helpful to exclude perforation as a cause of rectal bleeding.

  3. Additional studies are helpful to exclude other causes of rectal bleeding depending on the history obtained.

3. Diagnosis

Meckel's scan: A Meckel's scan involves the administration of 99mtechnetium pertechnetate followed by scintigraphy. The scan identifies areas of gastric mucosa and a will detect a Meckel's diverticulum if it has ectopic gastric mucosa.

Approximately half of all Meckel's diverticulum do not have gastric mucosa and thus do not cause bleeding and cannot be detected by a Meckel's scan. Most are asymptomatic although some can cause recurrent obstruction. A Meckel's diverticulum which does not have gastric mucosa may be detected on cross-sectional imaging, although only with a high degree of suspicion. A Meckel's diverticulum without gastric mucosa is often an incidental finding at the time of laparotomy, laparoscopy or autopsy.

Laboratory values are significant for a low hemoglobin, which can often be below 8 and is caused by acute hemorrhage. Acute hemorrhage causes vasoconstriction which often decreases the bleeding and helps to stabilize the patient while workup can be performed.

Differential diagnosis

Any cause of lower GI bleeding can present similarly to Meckel's diverticulum and could include the following.

  1. Inflammatory bowel disease - both Crohn's disease and ulcerative colitis can present with an acute GI bleed, although there are often symptoms that were present for months after taking a careful history. Weight loss, blood in the stool and fatigue have often been present for weeks to months. Inflammatory bowel disease often presents in teenage years, but can present in young children.

  2. Polyps - rectal bleeding can occur after a polyp sloughs off causing significant bleeding, often for 1-2 days. This typically occurs in younger children and is a classic cause of painless rectal bleeding.

Confirmatory tests

A Meckel's scan, or technetium 99m pertechnetate scan, is diagnostic if gastric tissue is present. A Meckel's scan detects gastric mucosa which is present in a majority of Meckel's diverticulum that bleed. It will not detect a Meckel's diverticulum that does not have gastric mucosa, although these are less likely to bleed.

4. Specific Treatment

Surgical resection of Meckel's diverticulum in necessary and often can be performed laparoscopically after stabilization.

Appendectomy is also often performed in conjunction.

5. Disease monitoring, follow-up and disposition

Outcome of a Meckel's diverticulum is excellent after surgical treatment.

There are some reports of increased malignancy in Meckel's diverticulum leading to recommendations that incidental Meckel's diverticulum be surgically removed. However, screening or evaluation of asymptomatic adults is not necessary.

Pathophysiology

The pathophysiology of a Meckel's diverticulum includes two aspects. First, the omphalomesenteric duct which typically involutes remains patent leading to a diverticulum.

The second aspect which leads to bleeding includes the presence of heterotopic gastric or pancreatic tissue. It is typically the presence of gastric tissue which secretes acid causing the development of ulcers and bleeding, although pancreatic tissue can also cause bleeding. Meckel's diverticulum without gastric mucosa do not typically bleed, but can be a cause of recurrent obstruction.

Epidemiology

A Meckel's diverticulum is found is as much as 2-5% of the population, however a majority are asymptomatic. It is likely that less than 5% of people with a Meckel's diverticulum will become symptomatic. Meckel's diverticulum are more common in males, although the reason for this finding is unknown.

What's the evidence?

Kahn, E, Daum, F, Feldman, M, Friedman, LS, Brandt, LJ. "Anatomy, histology, embryology, and developmental anomalies of the small and large intestine". Sleisenger & Fordtran's Gastrointestinal and Liver Disease. Saunders Elsevier. 2010.

(Overview of Meckel's diverticulum)

Park, JJ, Wolf, BG, Tollefson, M. "Meckel's Diverticulum: the Mayo Clinic experience with 1476 cases (1950-2002)". Annals of Surgery. vol. 241. 2005 March. pp. 529-33.

(A large institutional experience evaluating need for surgical intervention.)
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