eMedicine Specialties > Pediatrics: General Medicine > Gastroenterology

Meckel Diverticulum

Author: Simon S Rabinowitz, MD, PhD, Professor of Clinical Pediatrics, New York Medical College; Chairman, Chief and Medical Administrator, Department of Pediatrics, Chief, Pediatric Gastroenterology and Nutrition, Richmond University Medical Center
Coauthor(s): Pauline K Mills, MD, Staff Physician, Department of Pediatrics, New York Medical College, Richmond University Medical Center
Contributor Information and Disclosures

Updated: Nov 17, 2008

Introduction

Background

Meckel diverticulum (also referred to as Meckel's Diverticulum) is the most common congenital abnormality of the small intestine; it is caused by an incomplete obliteration of the vitelline duct (ie, omphalomesenteric duct). Although originally described by Fabricius Hildanus in 1598, it is named after Johann Friedrich Meckel, who established its embryonic origin in 1809.¹

Despite the availability of modern imaging techniques, diagnosis is challenging. Although Meckel diverticulum is usually of no medical significance, two types of complications can require clinical attention. One type involves ectopic mucosal tissue and most often leading to GI bleeding in younger children. In the second type, the sequelae of the diverticulum involve an aberrant intraabdominal structure.

Pathophysiology

Early in embryonic life, the fetal midgut receives its nutrition from the yolk sac via the vitelline duct. The duct then undergoes progressive narrowing and usually disappears by 7 weeks' gestation. When the duct fails to fully obliterate, different types of vitelline duct anomalies appear. Examples of such anomalies include (1) a persistent vitelline duct (appearing as a draining fistula at the umbilicus); (2) a fibrous band that connects the ileum to the inner surface of the umbilicus; (3) a patent vitelline sinus beneath the umbilicus; (4) an obliterated bowel portion; (5) a vitelline duct cyst; and, most commonly (97%) Meckel diverticulum, which is a blind-ending true diverticulum that contains all of the layers normally found in the ileum.²  The tip of the diverticulum is free in 75% of cases and is attached to the anterior abdominal wall or another structure in the remainder of cases.

Enterocystomas, umbilical sinuses, and omphaloileal fistulas are among the other congenital anomalies associated with Meckel diverticulum.

The diverticulum is usually supplied by the omphalomesenteric artery (a remnant of the vitelline artery), which arises from the ileal branch of the superior mesenteric artery. Usually, the artery terminates in the diverticulum; however, it has been reported to continue up to the abdominal wall in some cases. Rarely, these blood vessels persist in the form of fibrous remnants that run between the Meckel diverticulum and the abdominal wall or small bowel mesentery.

Meckel diverticulum occurs on the antimesenteric border of the ileum, usually 40-60 cm proximal to the ileocecal valve. On average, the diverticulum is 2.99 cm long and 1.92 cm wide. Slightly more than one half contain ectopic mucosa. Meckel diverticulum is typically lined by ileal mucosa, but other tissue types are also found with varying frequency.

The heterotopic mucosa is most commonly gastric. This is important because peptic ulceration of this or adjacent mucosa can lead to painless bleeding, perforation, or both. In one study, heterotropic gastric mucosa was found in 62% of cases, pancreatic tissue was found in 6%, both pancreatic tissue and gastric mucosa were found in 5%, jejunal mucosa was found in 2%, Brunner tissue was found in 2%,³ and both gastric and duodenal mucosa were found in 2%.² Rarely, colonic, rectal, endometrial, and hepatobiliary tissues have been noted.

Frequency

United States

The prevalence of Meckel diverticulum is usually noted to be approximately 2% of the population³ but published series range from 0.2-4%.⁴ Complications are only seen in about 5% of those with the anomaly.

International

Prevalence figures similar to those found in the United States have been reported in Europe and Asia.

Mortality/Morbidity

See Complications.

Race

No racial biases have been reported.

Sex

Although no sex-based difference was reported in studies that evaluated this condition as an incidental finding during operations or autopsies, males are as much as 3-4 times more prone to complications than females.

Age

The classic presentation in children is considered to be painless rectal bleeding in a toddler younger than 2 years. However, some series have found less than half of the children were younger than 2 years. 

Most other pediatric cases occur in patients aged 2-8 years, and the most common presentation continues to be hematochezia. In adults, obstruction and inflammation are more common presentations than lower GI bleeding. Several population-based studies have reported a decreased incidence of complications with increasing age, although other studies have not. Therefore, the issue of incidental diverticulectomy in older patients remains controversial.

Clinical

History

Most patients are asymptomatic. Meckel diverticulum is frequently an incidental finding when a barium study or laparotomy is performed for other abdominal conditions.

• Symptomatic Meckel diverticulum is virtually synonymous with a complication. This is estimated to occur in as many as 4-16% of patients.² Complications are the result of obstruction, ectopic tissue, or inflammation. In one study of 830 patients of all ages, complications included bowel obstruction (35%), hemorrhage (32%), diverticulitis (22%), umbilical fistula (10%), and other umbilical lesions (1%).
• In children, hematochezia is the most common presenting sign. Bleeding in adults is much less common.
  • Acute lower GI bleeding is secondary to hemorrhage from peptic ulceration. Such ulceration occurs when acid secreted by heterotopic gastric mucosa damages contiguous vulnerable tissue, often times resulting in direct erosion of a vessel. Clinically, hemorrhage is usually noted to be substantial painless rectal bleeding. However, some patients may present only with pain preceding the onset of hematochezia; this clinical presentation can often obscure the diagnosis.
  • Not all patients have abdominal pain; however, when present, it can be significant.
• Although intestinal obstruction in pediatrics is not considered very prevalent, some series report it in 25-40% of pediatric complications. It is the most common complication in adults. Obstruction can be the result of various mechanisms.²
  • Omphalomesenteric band (most frequent cause)
  • Internal hernia through vitelline duct remnants
  • Volvulus occurring around vitelline duct remnants
  • T-shaped prolapse of both efferent and afferent loops of intestine through a persistent vitelline duct fistula at the umbilicus in a neonate
  • Intussusception (when Meckel diverticulum itself acts as a lead point for an ileocolic or ileoileal intussusception)
• None of these mechanisms have clinical features that are pathognomonic, and the precise etiology is rarely known preoperatively. 
• Like other diverticula in the body, Meckel diverticulum can become inflamed. Diverticulitis is usually seen in older patients. Meckel diverticulum is less prone to inflammation than the appendix because most diverticula have a wide mouth, have very little lymphoid tissue, and are self-emptying.
  • The clinical presentation includes abdominal pain in the periumbilical area that radiates to the right lower quadrant.
  • Persistence of periumbilical pain or a history of bleeding per rectum may be helpful in distinguishing this entity from appendicitis.
  • Subacute or chronic inflammation of Meckel diverticulum is rare, but a few cases of tuberculosis and Crohn disease within the diverticulum have been reported.
• Less frequently, the Meckel diverticulum may develop benign tumors (eg, leiomyomas, angiomas, neuromas, lipomas) or malignant neoplasms (eg, sarcoma, carcinoid tumor,³ adenocarcinomas). Rarely, it may perforate from a swallowed fish bone or sewing needle.

Physical

Although most patients are asymptomatic, patients can present with various clinical signs, including peritonitis or hypovolemic shock. The 3 most common symptomatic presentations are GI bleeding, intestinal obstruction, and acute inflammation of the diverticulum.

• Most often, painless rectal bleeding (hematochezia) occurs suddenly and tends to be massive in younger patients.⁵ Bleeding occurs without prior warning and usually spontaneously subsides.
  • When a severe bleeding episode occurs, the patient can present in hemorrhagic shock. Tachycardia is the earliest clinical sign of early hemorrhagic shock, but hypotension may also be noted.
  • The color of the stool often provides physicians with a clue to determine the site of bleeding. This has been well addressed in a classic description of the types of rectal bleeding associated with Meckel diverticulum.
  • Prevalence of different types of bleeding has been described as follows:
    • Dark red (maroon) - 40%
    • Bright red - 35%
    • Bright red or dark red - 12%
    • Dark red or tarry - 6%
    • Tarry - 7%
  • When bleeding is rapid, stools are bright red or have an appearance like currant jelly. When slow bleeding occurs, the stools are black and tarry.
  • Most patients with intestinal obstruction present with abdominal pain, bilious vomiting, abdominal tenderness, distension, and hyperactive bowel sounds upon examination.
  • Patients may develop a palpable abdominal mass.
  • Occasionally, when patients do not present early or if the diagnosis is missed, the obstruction can progress to intestinal ischemia or infarction, the latter manifests with acute peritoneal signs and lower GI bleeding.
• Patients with diverticulitis present with either focal or diffuse abdominal tenderness. Usually, abdominal tenderness is more marked in the periumbilical region than the pain of appendicitis.
  • Children may present with abdominal guarding and rebound tenderness, in addition to abdominal tenderness.
  • Abdominal distention and hypoactive bowel sounds are late findings.
• Rarely, Meckel diverticulum has been reported to become incarcerated in the inguinal (Littre hernia),⁶  femoral, or obturator hernial sacs. 

Causes

Meckel diverticulum is caused by the failure of the omphalomesenteric duct to completely obliterate at 5-7 weeks' gestation, followed by one of the various complications listed above.

• Search for CME/CE on This Topic »

• Meckel Diverticulum (Pediatrics: Surgery)
• Meckel Diverticulum (Radiology)
• Meckel Diverticulum (General Surgery)
• Alimentary Tract Duplications (Pediatrics: Surgery)

• Pediatric Developmental Issues and Disorders
• Spotting an Asymptomatic Meckel's Diverticulum During Surgery -- What Next?
• Four-Year-Old With 3 UTIs is Likely to Exhibit Signs of What?