eMedicine Specialties > General Surgery > Abdomen

Meckel Diverticulum

Author: Nafisa K Kuwajerwala, MD, Staff Surgeon, Breast Oncology, William Beaumont Hospital
Coauthor(s): Yvan J Silva, MD, FRCS(C), FACS, Professor of Surgery, Program Director of Surgery, North Oakland Medical Centers, Wayne State University School of Medicine; Venkata Subramanian Kanthimathinathan, MD, Staff Physician, Department of General Surgery, Loma Linda University Medical Center
Contributor Information and Disclosures

Updated: Aug 19, 2008

Introduction

In the early 19th century, Johann Friedrich Meckel (1781-1833) wrote an important paper describing the diverticular remnant of the omphalomesenteric duct located at the ileum, a short distance from the caecum. Johann Meckel was not the first to recognize this uncommon anomaly; in 1598, Fabricus Hildanus had reported this as an unusual diverticulum of the small intestine. In 1809, Johann Meckel published a meticulous description of its anatomy and embryonic origin, and it is now known by his name.

Frequency

Autopsy records show that the incidence is about 2% of the general population.

Although most commonly discovered as an incidental finding on laparotomy or laparoscopy, this entity can be associated with life-threatening disease states. Retrospective studies suggest that the onset and frequency of complications decrease during life. The risk of complications ranges from 4-25% in various studies.

The male-to-female ratio of patients with symptomatic diverticula is 3:1, but it is 1:1 for patients with asymptomatic diverticula. The issue of managing a Meckel diverticulum in an asymptomatic patient is controversial. The risk of postoperative complications following excision of an incidental diverticulum is as much as 8%.

Presentation

The most common presentation is as an incidental finding at laparotomy. Complications manifest as ulceration, hemorrhage, small bowel obstruction, diverticulitis, and perforation. In an excellent population-based study covering patient data over 42 years by Cullen et al, the lifetime risk of developing a complication that requires surgery is estimated to be 6.4%.¹

• Hemorrhage
  • Hemorrhage is the most common complication, with an incidence of about 20-30% of all complications. It is more common in children younger than 2 years and in males.
  • The patient complains of passing bright red blood in the stools. Bleeding may vary from minimal recurrent episodes of hematochezia to massive, shock-producing hemorrhage. The rate of bleeding can be assessed by the quantity of blood lost in the stools, the appearance of the material passed through the rectum, and the hemodynamic state. Hemorrhage from a Meckel diverticulum may or may not be associated with abdominal pain or tenderness. Patients may also present with weakness and anemia and may have a history of self-limiting episodes of intestinal bleeding.
    • If the hemorrhage is brisk, the blood expelled in the stools will be bright red.
    • If the stools are tarry, the bleeding is probably minor and associated with slow intestinal transit.
    • Tarry stools are commonly observed in patients with upper GI bleeding because transit through the bowel produces alteration of blood.
    • Currant jelly stools are associated with copious mucus owing to the ischemia of the bowel and are commonly observed in intussusception.
    • Blood-streaked stools are a sign of fissure in ano.
  • The gastric mucosa found in the diverticulum may form a chronic ulcer and may also damage the adjacent ileal mucosa because of acid production. Ectopic gastric mucosa is found in about 50% of all Meckel diverticulum; in bleeding Meckel diverticulum, the incidence increases to 75%. Perforation may occur, and the patient then presents with an acute abdomen, often associated with air under the diaphragm, best visualized on an erect chest radiograph.
  • Diagnosis of a bleeding Meckel diverticulum is established by technetium Tc 99m-pertechnate radioisotope scanning. This isotope, administered intravenously, is readily taken up by gastric mucosa. Reportedly, a size of 1.8 cm² of ectopic gastric mucosa in Meckel diverticulum is required for a positive result.
    • Pentagastrin, which has been known for several years to increase the acid production of ectopic gastric mucosa, acts by enhancing radioisotope uptake by the cells. Using a histamine 2 (H2) receptor blocker with pentagastrin provides a synergistic effect, since it blocks intraluminal release and promotes retention of the isotope. The value of technetium Tc 99m-pertechnate scanning is more specific in children.
    • The incidence of false-negative results is high, especially in adults; therefore, a negative scan finding does not exclude a Meckel diverticulum. The use of pentagastrin and an H2 receptor blocker helps minimize the number of false-negative results.
    • False-positive results are observed in patients with intussusception, volvulus, obstruction of the small intestine, acute appendicitis, carcinoid of the appendix, or carcinoma of the caecum.
  • When a patient presents with painless lower GI bleeding, Meckel diverticulum should always be suspected. Panendoscopy helps exclude upper GI or colorectal disease, the two most common sites of GI bleeding.
• Intestinal obstruction
  • This is another frequent complication and is observed in 20-25% of patients with symptomatic Meckel diverticulum. The diagnosis of bowel obstruction due to Meckel diverticulum may not be established preoperatively. At exploration, Meckel diverticulum may be identified as the cause of obstruction. Various mechanisms of intestinal obstruction occur with Meckel diverticulum as a causative factor. Because the omphalomesenteric duct may be attached to the abdominal wall by a fibrotic band, a volvulus of the small bowel around the band may occur. The diverticulum may also form the lead point of an intussusception and cause obstruction. Infrequently, a tumor arising in the wall of the diverticulum may form the lead point for intussusception. When incarcerated in an inguinal hernia, a Meckel diverticulum is called Littré hernia.
  • Patients with intestinal obstruction due to Meckel diverticulum present with abdominal pain, vomiting, and obstipation. Roentgenography of the abdomen may indicate an ileus or frank stepladder air fluid levels, as observed in dynamic intestinal obstruction.
  • In cases of intussusception, patients may also present with a palpable lump in the lower abdomen and currant jelly stools.
• Diverticulitis
  • This condition occurs in approximately 10-20% of patients with symptomatic Meckel diverticulum and occurs more often in the elderly population. Patients may present with symptoms of intermittent, crampy abdominal pain and tenderness in the periumbilical area. Perforation of the inflamed diverticulum leads to peritonitis.
  • Stasis in the diverticulum, especially in one with a narrow neck, causes inflammation and secondary infection leading to diverticulitis. Diverticular inflammation can lead to adhesions, which cause intestinal obstruction.
• Umbilical anomalies
  • These occur in up to 10% of patients. The anomalies consist of fistulas, sinuses, cysts, and fibrous bands between the diverticulum and the umbilicus.
  • A patient may present with a chronic discharging umbilical sinus, superimposed by infection or excoriation of periumbilical skin. There may be a history of recurrent infection, sinus healing, or abdominal wall abscess formation. When a fistula is present, intestinal mucosa may be identified on the skin.
  • Cannulation and injection with radiographic contrast helps delineate the entire tract and helps in planning a surgical approach for cure. A discharging sinus should be approached surgically with a view toward correction. Exploratory laparotomy may be required.
  • When found at laparotomy, a fibrous band should be excised because of the risk of internal herniation and volvulus.
• Neoplasm
  • This is the least commonly associated pathology and is reported in approximately 4-5% of complicated Meckel diverticulum cases.
  • Of the various types of tumors reported, leiomyoma is the most frequent tumor, followed by leiomyosarcoma, carcinoid, and fibroma. One case of ectopic gastric adenocarcinoma has been reported.
• Other reported complications are vesicodiverticular fistulas, "daughter" diverticula (formation of a diverticulum within a Meckel diverticulum), and formation of stones and phytobezoar in the Meckel diverticulum.

Indications

Symptomatic Meckel diverticulum

Absolute indications for resection are hemorrhage, intestinal obstruction, diverticulitis, and umbilico-ileal fistulas.

Incidentally discovered Meckel diverticulum

Resection is recommended for (1) patients younger than 40 years; (2) diverticula longer than 2 cm; (3) diverticula with narrow necks; (4) diverticula with fibrous bands; (5) suspected ectopic gastric tissue; and (6) inflamed, thickened diverticula.

Removal of a healthy diverticulum in the presence of peritonitis, Crohn disease, ulcerative colitis, or any other complication that would militate against resection is not advised.

Relevant Anatomy

As a congenital anomaly, this is a true diverticulum that includes all 3 coats of the small intestine.

• The following "rule of two" applies to the condition:
  • It affects 2% of the population.
  • It is approximately 2 inches in length.
  • It is found 2 feet proximal to the ileocecal valve.
• Generally, a Meckel diverticulum ranges from 1-12 cm in length and is found 45-90 cm proximal to the ileo-cecal valve. It frequently contains heterotropic tissue; when it does, gastric mucosa accounts for 50%.
• Pluripotential cells line the omphalomesenteric duct; thus, gastric, colonic, duodenal, and pancreatic mucosa may be present.
• The diverticulum may or may not be attached to the umbilicus with a fibrous cord.

Pathology: Ectopic gastric mucosa frequently secretes acid and damages the normal ileal mucosa. Because of the chronic acid injury, acute ileal ulcers form and may bleed or perforate. Benign tumors, such as lipoma, leiomyoma, and angioma, may arise in the wall of the Meckel diverticulum. Malignant change to leiomyosarcoma or of the ectopic gastric mucosa to adenocarcinoma has also been described.

Embryology: This is a vestigial remnant of the omphalomesenteric (vitellointestinal) duct. Human embryos initially have convex umbilical loops of primitive gut that communicate freely with the yolk sac through the omphalomesenteric (vitellointestinal) duct. As development proceeds, the duct normally becomes occluded and disappears entirely by weeks 8-10 of gestation.

• The following anomalies are caused by the persistence of the omphalomesenteric (vitellointestinal) duct (see Media file 1):
  • Persistence and patency of the entire tract leading to a congenital umbilico-ileal fistula
  • An outpouching diverticulum secondary to persistence of the proximal part of the vitelline duct (Meckel diverticulum) with or without a fibrous cord
  • Persistence of the duct near the umbilicus, forming an umbilical sinus
  • Fluid-filled cysts (enterocystomas) either intra-abdominal or just below the umbilical skin because of persistence of the middle portion of the duct
  • Obliteration of the lumen of the duct but persistence of the duct, forming a fibrous cord
• Meckel diverticulum is the most common anomaly.

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