Meckel’s diverticulum is the most common congenital abnormality found in the gastrointestinal tract, affecting about two percent of the population. Characterized by a small, pouch-like bulge on the wall of the small intestine, it is a remnant of a structure present during early fetal development. While often asymptomatic and found incidentally, its presence can lead to severe complications requiring immediate medical attention.
Embryological Origin and Anatomical Location
Meckel’s diverticulum forms due to the incomplete disappearance of the vitelline duct during fetal development. This duct, also known as the omphalomesenteric duct, connects the developing midgut to the yolk sac. Normally, this structure atrophies and obliterates by the ninth week of pregnancy; failure to do so leaves a persistent pouch.
This residual pouch is typically located on the anti-mesenteric border of the ileum, approximately two feet upstream from the ileocecal valve. Anatomical features are often summarized by the “Rule of 2s.” The diverticulum is usually about two inches long and is found in about two percent of the population.
The Rule of 2s also notes that the diverticulum can contain two types of ectopic tissue, most commonly gastric or pancreatic tissue, and is about two times more likely to cause symptoms in males. The presence of this misplaced tissue is crucial, as it often dictates whether the diverticulum will cause a problem.
Clinical Manifestations and Potential Complications
While the majority of individuals with Meckel’s diverticulum never experience symptoms, a small percentage (four to six percent) develop complications that necessitate medical intervention. The most common presentation in young children is painless gastrointestinal bleeding. This occurs because ectopic gastric tissue within the diverticulum secretes acid, causing ulceration in the adjacent, acid-sensitive ileal lining.
The bleeding can manifest as bright red blood in the stool or sometimes as dark, tarry stools, depending on the rate of bleeding and intestinal transit time. Intestinal obstruction is another major complication, which can happen at any age but is more common in adults. Obstruction can result from the diverticulum acting as a lead point for an intussusception, where one segment of the intestine telescopes into another.
Obstruction may also be caused by fibrous bands remaining from the vitelline duct, which can constrict the bowel, or by a volvulus (a twisting of the small intestine around the diverticulum’s blood supply). Inflammation of the diverticulum, known as Meckel’s diverticulitis, is a third common complication. This inflammation often mimics acute appendicitis, presenting with abdominal pain and tenderness that makes preoperative diagnosis challenging.
Identification and Diagnostic Procedures
Diagnosing a symptomatic Meckel’s diverticulum can be challenging because its symptoms often overlap with more common conditions like appendicitis or Crohn’s disease. The primary diagnostic tool used when bleeding is suspected, particularly in children, is the Technetium-99m pertechnetate scan, often called a Meckel scan. This nuclear medicine scan works by detecting the uptake of the radioactive tracer by the acid-producing ectopic gastric mucosa present in the diverticulum.
While highly sensitive in children, the Meckel scan’s accuracy is lower in adults. For cases involving obscure or occult bleeding that the Meckel scan does not explain, other methods may be employed. Capsule endoscopy, where the patient swallows a tiny camera, can sometimes visualize the diverticulum or the associated ulceration, though the capsule can pass quickly, making visualization difficult.
Computed tomography (CT) scans are generally not ideal for directly visualizing the diverticulum itself, but they are useful for diagnosing complications. A CT scan can effectively show signs of intestinal obstruction, inflammation (diverticulitis), or perforation. Angiography, which images the blood vessels, can sometimes identify the anomalous blood supply to the diverticulum in cases of brisk bleeding.
Management and Treatment Options
Treatment for Meckel’s diverticulum is definitively surgical when the patient is symptomatic or has developed complications. The specific surgical approach depends on the patient’s presentation and the condition of the diverticulum. For uncomplicated cases with a narrow base, a simple diverticulectomy, which involves removing the pouch and closing the intestinal wall, may be performed.
If the base of the diverticulum is wide, if the adjacent ileum is ulcerated, or if there is a perforation, a segmental resection may be required. This procedure removes the diverticulum along with a small section of the adjacent small bowel, followed by surgical reconnection. Surgery can be performed using either an open approach or a minimally invasive laparoscopic technique.
The management of an incidentally discovered, asymptomatic Meckel’s diverticulum is a matter of debate. Many surgeons consider prophylactic removal, especially in patients under 50 years old, or when the diverticulum is longer than two centimeters, has a narrow base, or appears to contain ectopic tissue. Removing the diverticulum eliminates the lifelong risk of future, potentially life-threatening complications.