Chapter 49: Meckel's Diverticulum

• The classical presentation of Meckel's diverticulum is painless bright-red bleeding per rectum.

• The nuclear medicine technetium-99m pertechnetate scan (Meckel's scan) is the imaging procedure of choice for the diagnosis of Meckel's diverticulum.

Bleeding per rectum is a common complaint among children seeking care at an emergency department (ED). In general, the differential diagnosis of hematochezia can be divided into conditions causing painful or painless rectal bleeding. Large volume, painless rectal bleeding suggests a specific, localizable lesion. The most common causes of such painless rectal bleeding in children are Meckel's diverticulum and colonic juvenile polyps.

Meckel's diverticulum is a persistent remnant of the omphalomesenteric duct that is seen in 2% of the population.¹ A typical Meckel's diverticulum is approximately 2 in (5 cm) long and is located on the antimesenteric border of the ileum, most commonly within 2 ft (approximately 60 cm) of the ileocecal valve, and, thus, is usually located in the right lower quadrant. More than 60% of patients who develop symptoms are younger than 2 years of age, and there are two types of mucosa, gastric and pancreatic, seen in the diverticulum. These findings of Meckel's diverticulum are commonly referred to as the “rule of twos.”

Approximately 4% to 35% of affected individuals experience symptoms associated with a Meckel's diverticulum.² The most common presentation in children younger than age 4 is painless rectal bleeding secondary to the acid secretion of functional ectopic gastric mucosa. This results in ulceration of the adjacent ileal mucosa and bleeding, which may present as hematochezia or less commonly as melena. Less-frequent presentations include Meckel's diverticulitis (which can mimic appendicitis), intestinal obstruction from intussusception, herniation of bowel through a patent omphalomesenteric fistula, or volvulus of bowel around a fibrous omphalomesenteric remnant attachment to the abdominal wall, and (rarely) perforation from an ingested foreign body trapped in the diverticulum.^3–6

Management of the Meckel's diverticulum consists of hemodynamic stabilization followed by surgical resection. A child who experiences gastrointestinal bleeding from a Meckel's diverticulum typically presents acutely, with large volume (>30 mL) rectal bleeding that may require transfusion. The diagnostic imaging modality of choice is the nuclear medicine Technetium-99m pertechnetate scan (Meckel's scan).⁷ It localizes ectopic gastric mucosa that is found within the Meckel's diverticulum (Fig. 49-1) and elsewhere such as in enteric duplication cysts.^2,8 A technetium-99m pertechnetate scan identifies the lesion in approximately 80% to 90% of cases.

False-positive results can occur with ureteral obstruction, inflammatory masses such as those seen in Crohn's disease, abscess, arteriovenous malformation, or intussusception. A negative scan should not delay surgical intervention if bleeding from a Meckel's diverticulum is strongly suspected. Technetium 99m-labeled red cell scan, also called a “bleeding scan,” can also help to localize a lesion that bleeds intermittently or at a low rate (0.1–0.3 mL/min or 500 mL/day) and eludes endoscopic detection. Labeled red cells remain in circulation for up to 5 days, which allows detection of intermittent bleeding. In rare cases in which Meckel's diverticulum is strongly suspected and the Meckel's scan yields negative results, abdominal computed tomography scan, angiography, and exploratory laparoscopy can be considered.⁹ Once confirmed, the definitive treatment is excision of the lesion.

Other possibilities for painless rectal bleeding include juvenile colonic polyps, and, less commonly, hemangiomas, venous malformations, or a brisk upper gastrointestinal bleed. The investigations for these conditions are beyond the scope of ED management.