Introduction
Background
Meckel diverticulum represents a true diverticulum of the ileum containing all 3 layers of the bowel wall. Meckel diverticulum develops if the omphalomesenteric or vitelline duct, which connects the primitive midgut with the yolk sac, fails to obliterate, which normally occurs at 7-8 weeks of gestation. Heterotopic tissue, including gastric mucosa and pancreatic tissue, is present in 50% of patients.
Symptoms resulting from a Meckel diverticulum occur because of complications and are more frequent in children than in adults and include hemorrhage and intestinal obstruction. Hemorrhage is usually due to erosion of adjacent ileal mucosa by acid produced by ectopic gastric mucosa. Intestinal obstruction is most often due to volvulus about the Meckel diverticulum or intussusception with the diverticulum as the lead point.1
Meckel diverticulum is notoriously difficult to diagnose at both clinical and imaging examination because the symptoms and imaging features are nonspecific.1,2,3,4,5
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Specialty Site Radiology
Specialty Site Gastroenterology
Resource Center Diverticulosis
Pathophysiology
Ectopic gastric or pancreatic mucosa is found in 50% of patients with Meckel diverticula. Rarely, colonic or hepatobiliary tissue is found. Symptoms may develop because of ulceration within the gastric or adjacent ileal mucosa and gastrointestinal bleeding. Intestinal obstruction, perforation, and inflammation are further complications (see Mortality/Morbidity, below).5,6
Single or multiple enteroliths may develop within the lumen of the diverticulum in as many as 10% of patients. Most enteroliths show a peripheral calcification. Obstruction of the lumen by an enterolith may lead to diverticulitis. Extrusion of an enterolith into the lumen of the small bowel may cause intestinal obstruction similar to a gallstone ileus. Herniation of a Meckel diverticulum into the inguinal canal is called a hernia of Littre.1,7
Frequency
United States
Meckel diverticulum is found in 2-3% of individuals at autopsy, and it is the most common congenital anomaly of the gastrointestinal tract.
International
Worldwide, the frequency of Meckel diverticulum is the same as that in the United States.
Mortality/Morbidity
Complications resulting from a Meckel diverticulum occur in 20% of patients. Most patients present with unexplained lower gastrointestinal bleeding. In most of these patients (95%), ectopic gastric mucosa within the diverticulum causes the bleeding.3
The second most common complication is intestinal obstruction, which results either from intussusception of the diverticulum into the lumen of the small bowel (inverted diverticulum) or from a volvulus. A volvulus occurs around a fibrous band attaching the omphalomesenteric diverticulum to the umbilicus. The diverticulum may become inflamed as a result of obstruction by an enterolith. The diverticulum may become herniated into the inguinal canal and cause intestinal obstruction.1,7
Rarely, benign and malignant tumors may both occur within a Meckel diverticulum and include polyps, carcinoid tumors, adenocarcinoma, and sarcoma.
The incidence of tumors reported with Meckel diverticulum is 0.5-3.2%. Occasionally, an ulcer in a patient with Meckel diverticulum becomes perforated, leading to peritonitis. The highest morbidity and mortality rates occur with volvulus.
Related eMedicine topics:
Gastrointestinal Bleeding, Lower
Gastrointestinal Bleeding, Upper
Lower Gastrointestinal Bleeding: Surgical Perspective
Upper Gastrointestinal Bleeding: Surgical Perspective
Race
No race predilection exists.
Sex
The male-to-female ratio is 3:1.
Age
Most patients with symptoms of Meckel diverticula present when they are younger than 10 years.8,9
Anatomy
The primitive endodermal tube of the gut is divided into the foregut, which is supplied by the celiac axis; the midgut, which is supplied by the superior mesenteric artery; and the hindgut, which is supplied by the inferior mesenteric artery. Early in development, the rapid proliferation of the gut wall obliterates the lumen, which is followed by recanalization. The midgut enlarges rapidly during the first 5 weeks of gestation and becomes too large for the abdominal cavity; subsequently, it is herniated into the umbilical cord.
The apex of the herniated midgut is continuous with the vitellointestinal duct and the yolk sac, which, even at this early stage of development, is reduced to a fibrous strand. The axis of the herniated midgut is formed by the superior mesenteric artery, which subdivides the midgut into a cephalic and caudal limb. The cephalic limb eventually forms most of the upper small bowel, while the caudal limb forms the terminal 60 cm or so of the small bowel, cecum, and colon as far as the junction of the proximal two thirds and distal one third of the transverse colon.
At approximately the 10th week of gestation, the midgut begins its return into the abdominal cavity. This return occurs by a highly complex developmental process, and as a result, numerous anomalies of the bowel may ensue, which include bowel atresias and stenoses, abnormalities of the vitellointestinal duct, failure of cecal descent, malrotation, malfixation, reversed bowel rotation, and exomphalos.10
Meckel diverticulum is a remnant of the embryonic vitellointestinal duct, which is a communication between the primitive midgut and the yolk sac; thus, a Meckel diverticulum is always on the antimesenteric border. Occasionally, the diverticulum ends in a fibrous solid strand. The vitellointestinal duct may persist as a fistula or fibrous band connecting the small bowel to the umbilicus or as a cyst within a fibrous band passing from the antimesenteric border of the small bowel to the umbilicus (see Images 1-4).
Presentation
Patients may present with acute or chronic gastrointestinal bleeding. Some patients are evaluated primarily for anemia. Vague pain in the lower abdomen is not unusual and may be present for several years. Patients may present with an acute abdomen resulting from acute diverticulitis, intestinal obstruction, or perforation; however, most patients with Meckel diverticula are asymptomatic, and the diverticulum is found incidentally on imaging, surgery, or autopsy.
Preferred Examination
Plain radiography, barium studies, angiography, computed tomography (CT), ultrasonography, and scintigraphy all play complementary roles in the diagnosis of the complications of Meckel diverticulum. The diagnosis is notoriously difficult and remains a continuing challenge for the radiologist.1,4,5,8,9,10,11,12,13,14,15
Limitations of Techniques
In all imaging modalities, findings of Meckel diverticulum are nonspecific. Most Meckel diverticula are diagnosed during surgery or autopsy, with imaging playing a secondary role. The most sensitive technique is scintigraphy, and various modifications to imaging techniques have been devised to improve sensitivity. Ultrasonography and CT are improving and can help in making an anatomic diagnosis.
Differential Diagnoses
More on Meckel Diverticulum |
 Overview: Meckel Diverticulum |
| Imaging: Meckel Diverticulum |
| Follow-up: Meckel Diverticulum |
| Multimedia: Meckel Diverticulum |
| References |
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References
Pantongrag-Brown L, Levine MS, Buetow PC, et al. Meckel''s enteroliths: clinical, radiologic, and pathologic findings. AJR Am J Roentgenol. Dec 1996;167(6):1447-50. [Medline].
Ariga M, Suga K, Matsunaga N, et al. Failure to detect a huge Meckel''s diverticulum with abundant ectopic gastric mucosa on gastric mucosal scintigraphy with Tc-99m pertechnetate. Clin Nucl Med. May 2001;26(5):470-1. [Medline].
Ford PV, Bartold SP, Fink-Bennett DM, et al. Procedure guideline for gastrointestinal bleeding and Meckel''s diverticulum scintigraphy. Society of Nuclear Medicine. J Nucl Med. Jul 1999;40(7):1226-32. [Medline].
Groebli Y, Bertin D, Morel P. Meckel''s diverticulum in adults: retrospective analysis of 119 cases and historical review. Eur J Surg. Jul 2001;167(7):518-24. [Medline].
Hol L, Kuipers EJ. Clinical challenges and images in GI. Meckel's diverticulum. Gastroenterology. Aug 2007;133(2):392, 732. [Medline].
You JS, Chung SP, Park YS, Yu JS, Park YA. A case of strangulated small bowel obstruction caused by Meckel's diverticulum in an adult. J Emerg Med. Aug 2007;33(2):133-5. [Medline].
van Es HW, Sybrandy R. Diagnosis please. Case 19: enteroliths in a Meckel diverticulum. Radiology. Feb 2000;214(2):524-6. [Medline].
Emamian SA, Shalaby-Rana E, Majd M. The spectrum of heterotopic gastric mucosa in children detected by Tc- 99m pertechnetate scintigraphy. Clin Nucl Med. Jun 2001;26(6):529-35. [Medline].
Linebarger JS, Roy ML. Focus on diagnosis: common nuclear medicine studies in pediatrics. Pediatr Rev. Nov 2007;28(11):415-7. [Medline].
Delle Chiaie L, Neuberger P. Early prenatal sonographic detection of an uncomplicated Meckel diverticulum. Ultrasound Obstet Gynecol. Oct 2007;30(5):790-1. [Medline].
Mitchell AW, Spencer J, Allison DJ, Jackson JE. Meckel''s diverticulum: angiographic findings in 16 patients. AJR Am J Roentgenol. May 1998;170(5):1329-33. [Medline].
Navarro O, Dugougeat F, Kornecki A, et al. The impact of imaging in the management of intussusception owing to pathologic lead points in children. A review of 43 cases. Pediatr Radiol. Sep 2000;30(9):594-603. [Medline].
Nolan DJ. The true yield of the small-intestinal barium study. Endoscopy. Aug 1997;29(6):447-53. [Medline].
Omar AM, Al-Saee''d TA, Elgazzar A. Scintigraphic pattern of intestinal duplication on a Meckel''s diverticulum scan. Clin Nucl Med. Oct 1998;23(10):708-9. [Medline].
Swaniker F, Soldes O, Hirschl RB. The utility of technetium 99m pertechnetate scintigraphy in the evaluation of patients with Meckel''s diverticulum. J Pediatr Surg. May 1999;34(5):760-4; discussion 765. [Medline].
Okazaki M, Higashihara H, Yamasaki S, et al. Arterial embolization to control life-threatening hemorrhage from a Meckel''s diverticulum. AJR Am J Roentgenol. Jun 1990;154(6):1257-8. [Medline].
Further Reading
Keywords
Meckel's diverticulum, Meckel diverticula, diverticulum of the ileum, intestinal obstruction, intestinal hemorrhage, hernia of Littre
