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Emergency and Acute Medicine – Meckel Diverticulum
Basics description
Meckel diverticulum is the most common congenital abnormality of the gastrointestinal tract and results from incomplete obliteration of the omphalomesenteric duct. It is a true diverticulum containing all layers of the bowel wall. Approximately half contain normal ileal mucosa, while the remainder contain ectopic tissue, most commonly gastric, but also pancreatic, duodenal, colonic, endometrial, or hepatobiliary mucosa. The classic “rule of 2’s” applies: it occurs in about 2% of the population, carries a 2% lifetime risk of complications that decreases with age, is usually around 2 inches long, and is located within 2 feet of the ileocecal valve. Symptoms commonly occur around 2 years of age, with nearly half of symptomatic patients presenting before age 2. Although prevalence is similar in males and females, males are more often symptomatic. Complications differ by age, with obstruction and diverticulitis more common in adults and hemorrhage and obstruction more common in children. The mean age of presentation is about 10 years, and current mortality is extremely low.
Etiology
Meckel diverticulum arises from a remnant of the omphalomesenteric duct, which normally regresses by the seventh week of gestation.
Pathophysiology and complications
Obstruction can occur when the diverticulum is attached to the umbilicus, abdominal wall, or other viscera, or when it is free and acts as a lead point. This may result in intussusception, with the diverticulum serving as the leading edge, or volvulus caused by a persistent fibrous band that allows bowel rotation. Diverticulitis occurs when the opening of the diverticulum becomes obstructed, followed by bacterial infection, and often presents similarly to acute appendicitis, which is the most common preoperative diagnosis.
Pediatric considerations
Meckel diverticulum is the most common cause of significant lower gastrointestinal bleeding in children. It typically presents before 5 years of age with episodic, painless, brisk, bright-red rectal bleeding.
Diagnosis, signs, and symptoms
Patients generally present in one of three ways. Rectal bleeding occurs due to hemorrhage from mucosal ulceration associated with ectopic gastric tissue. Vomiting may result from bowel obstruction caused by volvulus, intussusception, or intraperitoneal bands. Abdominal pain, often appendicitis-like, may occur with an inflamed or perforated diverticulum. Associated findings include fever, malaise, weakness, fatigue, abdominal distention, changes in bowel habits, hematochezia or melena, and in advanced cases, peritonitis or septic shock. Tachycardia and hypotension may be present due to pain or blood loss.
Essential workup
Meckel diverticulum can produce a wide variety of nonspecific symptoms, and fewer than 10% of cases are diagnosed preoperatively. It should be considered in patients with recurrent nonspecific abdominal pain, nausea and vomiting, or rectal bleeding. History and physical examination may narrow the diagnosis but are not definitive. Rectal examination is mandatory, and nasogastric tube placement may help rule out an upper gastrointestinal bleed.
Diagnostic tests and interpretation
Laboratory evaluation may reveal a decreased hematocrit from bleeding or leukocytosis in cases of diverticulitis, perforation, or gangrene. Electrolytes, renal function, and coagulation studies should be obtained, and type and screen or cross-match is required with significant bleeding. Computed tomography of the abdomen and pelvis is useful for suspected infection or bowel obstruction but cannot reliably diagnose Meckel diverticulum. Abdominal radiographs may screen for obstruction but are not diagnostic. A technetium-99m pertechnetate scan (Meckel scan) can identify heterotopic gastric mucosa and is highly accurate in children but less sensitive in adults. Small bowel enteroclysis, barium enema, angiography, ultrasound, or laparoscopic evaluation may be used in selected cases. Colonoscopy is not helpful.
Differential diagnosis
In adults, the differential includes appendicitis, adhesions, bowel obstruction, diverticulitis, hemorrhoids, inflammatory bowel disease, internal hernias, intussusception, peptic ulcer disease, pseudomembranous colitis, and volvulus. In children, considerations include anal fissures, appendicitis, atresia, gastroenteritis, hemolytic–uremic syndrome, Henoch–Schönlein purpura, intussusception, malrotation, milk allergy, strictures, and volvulus.
Treatment and emergency management
Prehospital management includes establishing intravenous access for patients with rectal bleeding or abdominal pain. Initial stabilization focuses on resuscitation and early surgical consultation. Hypotension is treated with aggressive fluid resuscitation, packed red blood cell transfusion for brisk bleeding, and vasopressors if septic shock is present. In the emergency department, gastrointestinal bleeding is managed with fluids and transfusion as indicated, Foley catheter placement to monitor urine output, and nasogastric tube placement to exclude brisk upper gastrointestinal bleeding. Obstruction requires nasogastric decompression and surgical consultation. Suspected diverticulitis or perforation requires nil per os status, preoperative antibiotics, and urgent surgical evaluation.
Definitive management
Symptomatic Meckel diverticula should be surgically resected. In children, asymptomatic Meckel diverticula discovered incidentally during laparotomy are generally resected to prevent future complications.
Disposition and follow-up
Admission is required for presumptive or confirmed Meckel diverticulum associated with diverticulitis, obstruction, intussusception, hemorrhage, or volvulus. There are no discharge criteria from the emergency department for suspected cases. Postoperative surgical follow-up is required.
Pearls and pitfalls
Painless, brisk, bright-red rectal bleeding in an infant is most often caused by Meckel diverticulum. The condition presents with a broad range of complications, including obstruction, intussusception, and hemorrhage, and is frequently diagnosed intraoperatively during surgery for presumed appendicitis. Remember the rule of 2’s to aid clinical recognition.
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