An 18 month old male is brought to the ED by his parents with a chief complaint of passing large amounts of dark red blood from his rectum, and black jelly-like stools of two days duration. The child does not appear to be in acute distress at rest, although his parents say that he seems to sleep more and looks paler than normal over the past 24 hours. Two days ago they were alarmed by maroon-colored blood on the child's bedding and oozing out the side of his diaper. He has not cried, complained, or shown any signs of focal pain or discomfort thus far. He has not vomited and continues to feed regularly. Prior to the onset of symptoms, he is reported as having a good appetite and is a generally "healthy and active baby" with no significant PMH.
Exam: VS T 37.4 (rectal), P150, RR 40, BP 90/50, oxygen saturation 100% in room air. His weight, height and head circumference are at the 50th percentile. He is pale and quiet, lying supine on the exam table. HEENT exam is significant for pale conjunctiva and lips. His neck is supple, non-tender, no bruits, no lymphadenopathy. His heart is slightly tachycardic, regular rhythm, no murmurs, no rubs, no gallops. His lungs are clear to auscultation. His abdomen is mildly distended with possible generalized tenderness upon palpation. No inguinal hernias are noted. Testes and penis are normal. A small amount of dark red blood is present in the diaper which is guaiac positive.
Labs: WBC 7,000, hemoglobin 9.6 g/dl, hematocrit 31%, MCV 67. Bleeding from a Meckel's diverticulum is suspected. A Tc-99m pertechnetate scintigraphy scan (a "Meckel's scan") is ordered, which demonstrates an area of focal uptake in the right lower quadrant of the abdomen. This focus appears at the same time as gastric activity, and its intensity increases in parallel with gastric activity. These findings are consistent with ectopic gastric tissue in a Meckel's diverticulum.
He is given an IV normal saline infusion. A transfusion is contemplated, but held off for the time being. A surgeon is consulted, and an emergent laparotomy is performed in which a portion of the patient's ileum is resected containing a 6 cm x 1.5 cm ulcerated appendage (a Meckel's diverticulum). He recovers well postoperatively.
Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, affecting about 2% of the population. Meckel's diverticulum affects the distal ileum and represents the remnants of the proximal end of the embryologic yolk stalk (i.e., the omphalomesenteric or vitelline duct) which normally obliterates completely by the 8th week of gestation. While most cases of Meckel's diverticulum are asymptomatic, complications such as perforation, hemorrhage from peptic ulceration, intussusception, volvulus or intestinal obstruction are associated life-threatening disease states.
During early embryonic development, the omphalomesenteric duct connects the midgut to the yolk sac, allowing free communication between the compartments. Starting from the 7th gestational week, this duct undergoes progressive narrowing, becomes occluded, and ultimately disappears completely by the 8th week (1). For reasons not well understood, the normal obliteration of the duct fails to occur in 1-3% of the population. When this happens, possible outcomes include (2):
1. Persistence and patency of the entire tract leading to a congenital umbilico-ileal fistula (presenting as a draining fistula at the umbilicus).
2. An outpouching diverticulum secondary to persistence of the proximal part of the vitelline duct (Meckel's diverticulum) with or without a fibrous band connecting the ileum to the inner surface of the umbilicus.
3. Persistence of the duct deep to the umbilicus, forming an umbilical sinus.
4. Fluid-filled cysts (enterocystomas) either intra-abdominal or just below the umbilical skin because of persistence of the middle portion of the duct.
5. Obliteration of the lumen of the duct but persistence of the duct tissue, forming a fibrous omphalomesenteric ligament.
Meckel's diverticulum is the most common omphalomesenteric duct anomaly, accounting for 97% of reported cases (2). The prevalence of Meckel's diverticulum based on autopsy records is estimated to be 2-4% of the general population. The male:female ratio of patients with asymptomatic Meckel's diverticula is 1:1, however, males with the anomaly are 3 times more likely to develop complications at some point during their lives. Four to six percent of all Meckel's diverticula cases result in complications and classically present in infants 2 years old or younger (3).
There are a few studies suggesting familial inheritance of Meckel's diverticula, however no other evidence currently exists to support a genetic predisposition as a risk factor (4). Other congenital anomalies, such as cleft palate, bicornate uterus, and annular pancreas, have been noted in association with Meckel's diverticulum, and Meckel's diverticulum may be found more frequently in patients with Crohn's disease compared to the general population (5).
A Meckel's diverticulum is a finger-like projection located in the distal ileum, usually within 100 cm of the ileocecal valve, about 1-10 cm long, and 2 cm wide. In contrast to intestinal duplications and mesenteric cysts, a Meckel's diverticulum arises from the antimesenteric border of the bowel, has its own mesentery, and derives its blood supply from a terminal branch of the superior mesenteric artery (the embryonic right vitelline artery). It is also considered a true diverticulum as it contains all layers of the intestinal wall (2).
The mucosa of the Meckel's diverticulum is heterotopic in over 50% of all cases, with 80% gastric in origin. Although pancreatic acinar tissue, duodenal Brunner's glands, colonic mucosa, hepatobiliary, jejunal, rectal, and endometrial tissues, or a combination of these tissues is noted on occasion, heterotopic gastric mucosa is by far the most common tissue seen (6). Consequently, the ectopic gastric mucosa found in the diverticulum may form a chronic ulcer and may damage the adjacent ileal mucosa via increased acid secretion. Such peptic ulceration can lead to pain, bleeding, and/or perforation.
Meckel's is the most common cause of gastrointestinal bleeding in children. Painless melena or bright red blood per rectum is a classic presentation, but there are other presentations as well.
A few cases of large diverticula measuring up to 3.5 cm in diameter and 9 cm in length have been reported in newborns presenting with a palpable mass and intestinal obstruction (2).
The Meckel's rule of 2's (8):
. . . . . 1. Occurs in 2% of the population.
. . . . . 2. Only 2% of those with a Meckel's diverticulum will manifest clinical problems.
. . . . . 3. Usually located 2 feet proximal to the ileocecal valve and the diverticulum is approximately 2 inches long.
. . . . . 4. Symptoms commonly manifest at age 2 years.
Most Meckel's diverticula are asymptomatic and are found either during autopsy or incidentally on laparotomy, laparoscopy, or barium study for other abdominal conditions. It is controversial whether to attempt surgical correction of an asymptomatic Meckel's diverticulum found incidentally as the risk of developing postoperative complications may be as high as 8% in such cases (3).
When patients with a Meckel's diverticulum develop symptoms, a complication is almost always present. The principal complications of Meckel's diverticulum include ulceration, hemorrhage, small bowel obstruction, diverticulitis, and perforation (9).
Ulceration with subsequent hemorrhage (often hemodynamically significant, but usually not life threatening) 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 most common presentation is painless hematochezia due to ulceration within the diverticulum or adjacent intestinal mucosa as a consequence of acid secretion from ectopic gastric mucosa contained in the diverticulum (6). This represents the most common cause of painless hematochezia in patients less than 2 years old. Consequently, severe anemia or hemodynamic shock affects many of these children. Gastric mucosa with peptic ulceration is found in the vast majority of these cases (10).
Intestinal obstruction is another frequent complication and is observed in 20-25% of all symptomatic Meckel's diverticula and is attributable to intussusception, volvulus (often twisting around a persisting umbillical remnant), herniation, or entrapment of a loop of bowel through a defect in the diverticular mesentery (11). Patients with intestinal obstruction due to Meckel's diverticulum are usually older and present with abdominal pain, and vomiting. In cases of intussusception, patients may also present with a palpable mass in the lower abdomen and bloody (currant jelly) stools. Radiography of the abdomen may indicate an ileus or frank stepladder air fluid levels as observed in a bowel obstruction (8).
Diverticulitis occurs in approximately 10-20% of patients with symptomatic Meckel's 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, indistinguishable from appendicitis. Perforation of the inflamed diverticulum leads to peritonitis while stasis in the diverticulum causes inflammation and secondary infection leading to diverticulitis. Diverticular inflammation can lead to adhesions, which can cause intestinal obstruction (2).
Umbilical anomalies occur in up to 10% of patients with a symptomatic Meckel's diverticulum. The anomalies consist of fistulas, sinuses, cysts, and fibrous bands between the diverticulum and 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. 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 (12).
Neoplasm is the least commonly associated pathology and is reported in approximately 4-5% of complicated Meckel's diverticulum. Of the various types of tumors reported, leiomyoma is the most frequent tumor, followed by leiomyosarcoma, carcinoid, fibroma, sarcomas, benign mesenchymal tumors, and adenocarcinomas (2).
Plain film radiographs are rarely useful in detecting a Meckel's diverticulum, although these may be useful at identifying an intussusception or bowel obstruction. An upper GI series and barium enema are also unreliable detection modalities. In addition, barium absorbs pertechnetate and its use should never precede a 99mTc scan since this may give rise to false negative results (7).
Preoperative diagnosis of a bleeding Meckel's diverticulum is best established by a technetium-99m pertechnetate scintiscan (Meckel's scan). The isotope, administered intravenously, identifies ectopic gastric mucosa as it is readily taken up by parietal cells (13). In a positive scan, the patient develops immediate tracer localization in the stomach and in the right lower quadrant. This test has a sensitivity of about 75%, with 15% false-positive and 25% false-negative rates. Reportedly, a size of 1.8 square cm of ectopic gastric mucosa in a Meckel's diverticulum is required for a positive result. The accuracy of the Meckel's scan may be improved with the use of pentagastrin or cimetidine, which increase the uptake of pertechnetate by parietal cells (7).
False negative scans are seen in Meckel's diverticulum that do not contain ectopic gastric mucosa or those with rapid bleeding that prevents the accumulation of tracer in the diverticulum. False positive Meckel scans can also be caused by appendicitis, peptic ulcer, hemangioma, abscess, intussusception, Crohn's disease, small bowel lymphoma, dilated or ectopic renal collecting structures, abdominal aneurysm, Peutz-Jeghers syndrome, and intestinal duplications (2).
Depending on the presentation pattern, the differential diagnosis can include appendicitis, Crohn's disease, acute porphyria, intussusception, volvulus, small bowel obstruction, bezoar, juvenile colonic polyp, incarcerated hernia, Hirschsprung's disease, necrotizing enterocolitis, perforated viscus, gastroenteritis, Henoch-Schonlein purpura, peptic ulcer, constipation, urinary tract infection, sickle cell crisis, urolithiasis, ovarian torsion, etc. The differential diagnosis of abdominal pain alone, is extensive.
Preoperatively, hemodynamic stabilization and control over diverticular infection should be addressed when Meckel's diverticulum complications are present. Cimetidine has been used successfully to stop bleeding before diverticulectomy is performed and empiric antibiotic administration is also often indicated (7). NG tube placement can be useful in patients presenting with intestinal obstruction requiring nasogastric decompression, and it can also help rule out upper GI hemorrhage proximal to the ligament of Treitz (2).
Surgical resection is the standard treatment of choice for all patients with a symptomatic Meckel's diverticulum (7). As mentioned earlier, the morbidity associated with a Meckel's diverticulectomy precludes routine surgical resection if found incidentally. However, if the diverticulum is suspected to contain ectopic gastric mucosa, if fibrous bands extend to the umbilicus, if mesodiverticular bands are present, or if there is surrounding inflammation, surgical resection of the Meckel's diverticulum is indicated (3).
The reported surgical mortality rate for symptomatic Meckel's diverticulum patients is 2-5%. Symptomatic patients have a 10-12% incidence of early postoperative complications such as ileus, suture line or intestinal anastomotic leak, intra-abdominal abscess, and pulmonary embolism. Late postoperative complications occur in 6-8% of patients and consist of small bowel obstruction due to intestinal adhesions (12).
Questions
1. What is the most common congenital gastrointestinal anomaly?
2. What embryologic structure composes a Meckel's diverticulum?
3. Are Meckel's diverticula more likely to be found in males rather than females?
4. What kind of ectopic mucosa is commonly found inside of a Meckel's diverticulum?
5. How do Meckel's diverticula usually present?
6. How do young children with symptomatic Meckel's diverticula usually present?
7. What are the principal complications of Meckel's diverticula?
8. What is the most useful imaging modality used to diagnose a Meckel's diverticulum?
9. A false negative Meckel's scan could be due to what?
10. What is the Meckel's rule of 2's (four elements)?
Related x-rays
Meckel's Diverticulitis: Yamamoto LG. Periumbilical Abdominal Pain. In: Yamamoto LG, Inaba AS, DiMauro R. (eds). Radiology Cases In Pediatric Emergency Medicine, 1996, volume 4, case 9. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v4c09.html
Volvulus due to Meckel's: Yamamoto LG. Bowel Obstruction With Intra-Intestinal Sand. Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1996, volume 5, case 19. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v5c19.html
References
1. Sadler TW. Langman's Medical Embryology, 8th edition. 2000, Baltimore: Lippincott Williams & Wilkins, pp 295-296.
2. Keljo DJ, Squires RH Jr. Anatomy and Anomalies of the Small and Large Intestines. In: Feldman M, Scharschmidt BF, Sleisenger MH, Klein S (eds). Sleisenger & Fordtran's Gastrointestinal and Liver Disease, 6th edition. 1998, Philadelphia: W. B. Saunders Company, pp. 1426-1428.
3. Cullen JJ, Kelly KA, Moir CR. Surgical management of Meckel's diverticulum. An epidemiologic, population-based study. Ann Surg 1994;220(4): 564-568.
4. Matsukuma Y, Matsuo Y, Sakaguchi M. A case of siblings with Meckel's diverticulum diagnosed before operation. Acta Paediatr Jpn 1994;36(3):291-293.
5. Martin JP, Connor PD, Charles K. Meckel's diverticulum. Am Fam Physician 2000;61(4):1037-1044.
6. Crawford JM. The Gastrointestinal Tract. In: Cotran RS, Kumar V, Collins T (eds). Robbins Pathologic Basis of Disease, 6th edition. 1999, Philadelphia: W. B. Saunders Company, pp. 804-805.
7. Savides TJ, Jensen DM. Section I, Chapter 4. Acute Lower Gastrointestinal Bleeding. In: Friedman SL, McQuaid KR, Grendell JH (eds). Current Diagnosis & Treatment in Gastroenterology, 2nd edition. 2003, New York: Lange Medical Books/McGraw-Hill Companies, online version (no page numbers available).
8. Yamamoto LG. Bowel Obstruction With Intra-Intestinal Sand. In: Radiology Cases In Pediatric Emergency Medicine, 1996, Volume 5, Case 19. Available on CD-ROM and online at: www.hawaii.edu/medicine/pediatrics/pemxray/v5c19.html
9. Kuwajerwala NK, Silva YJ. Meckel Diverticulum. In: Daily BJ, Talavera F, Friedman AL, Zamboni P, Geibel J (eds). eMedicine Journal, 2002 Jul 31,3(7).
10. Wyllie R. Intestinal Duplications, Meckel Diverticulum, and Other Remnants of the Omphalomesenteric Duct. In: Behrman RE, Kliegman RM, Jenson HB (eds). Nelson Textbook of Pediatrics, 16th edition. 2000, Philadelphia: W. B. Saunders Company, pp 1137-1138.
11. Matsagas MI, Fatouros M, Koulouras B. Incidence, complications, and management of Meckel's diverticulum. Arch Surg 1995;130(2):143-146.
12. Moore T, Johnston AO. Complications of Meckel's diverticulum. Br J Surg 1976;63(6):453-454.
13. Yamamoto LG. Pediatric Abdominal Emergencies. In: Pediatric Emergency Medicine Database. October 2002, available online at: www.PEMdatabase.org
14. Shukla PC, Kamath B. Meckel Diverticulum. In: Maller ES, Konop R, Cuffari C, Schwartz S, Altschuler S (eds). eMedicine Journal, 2001 Oct 2, 2(10).
Answers to questions
1. Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, affecting about 2% of the population.
2. The embryologic yolk-stalk or omphalomesenteric or vitelline duct
3. Meckel's diverticula appear in males and females at equal frequencies, however, males are 3 times more likely to develop symptomatic or complicated Meckel's diverticula.
4. Gastric mucosa is present in 80% of all heterotopic cases.
5. Most cases of Meckel's diverticula are asymptomatic, are detected at autopsy, or incidentally during unrelated abdominal surgery.
6. The infant or young child who has a massive, painless bout of dark red rectal bleeding most likely has Meckel's diverticulum.
7. The principal complications of Meckel's diverticulum include ulceration, hemorrhage, small bowel obstruction (may be due to volvulus or intussusception), diverticulitis, and perforation.
8. A Meckel's scan (technetium-99m pertechnetate scintigraphy).
9. False negative scans are seen in Meckel's diverticulum that do not contain ectopic gastric mucosa and in Meckel's diverticulum with rapid bleeding that prevents the accumulation of tracer in the diverticulum.
10. Meckel's rule of four 2's: a) Occurs in 2% of the population, b) Only 2% of those with a Meckel's manifest clinical problems, c) Usually located 2 feet proximal to the ileocecal valve and the diverticulum is approximately 2 inches long, d) Symptoms commonly manifest at age 2 years.