Pediatric Meckel Diverticulum Workup

Updated: Sep 08, 2016
  • Author: Simon S Rabinowitz, MD, PhD, FAAP; Chief Editor: Carmen Cuffari, MD  more...
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Workup

Laboratory Studies

Routine laboratory findings, including CBC, electrolyte levels, glucose, BUN, creatinine levels, and coagulation screen results, are not helpful in establishing the diagnosis of Meckel diverticulum but are necessary to manage a patient with GI bleeding along with a type and cross.

Hemoglobin and hematocrit levels are low in the setting of anemia or bleeding.

Patients with significant bleeding develop anemia. In one series, 58% of children had average hemoglobin levels of less than 8.8 g/dL.

A prospective linear observational study of 73 children with a diagnosis of symptomatic Meckel diverticulum compared mean hemoglobin level before onset of symptoms and at presentation of rectal bleeding. The study demonstrated a correlation of 58% between Meckel diverticulum and hematochezia with a drop in hemoglobin of more than 2g/dL. [22]

Ongoing bleeding from a Meckel diverticulum can cause iron deficiency anemia. However, megaloblastic anemia can also be seen due to vitamin B12 or folate deficiency. These can occur secondary to small bowel overgrowth if dilation and/or stasis related to the diverticulum is present. Low albumin and low ferritin levels may lead to a diagnosis of inflammatory bowel disease.

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Imaging Studies

According to Mayo, "Meckel's Diverticulum is frequently suspected, often looked for, and seldom found." Preoperative diagnosis is difficult, especially if the presenting symptom is not GI bleeding. In one series, patients often had a correct preoperative diagnosis if the presenting symptom was GI bleeding, but only 11% of preoperative diagnoses were correct if other symptoms predominated. [23]

History and physical examination are of paramount importance for establishing a clinical diagnosis. Imaging studies are performed to confirm a clinical suspicion of Meckel diverticulum.

Plain radiography of the abdomen is of limited value. It may reveal evidence of nonbleeding complications, including enteroliths and signs of intestinal obstruction, such as air or air-fluid levels (see the image below), or perforation.

Anteroposterior view of abdominal radiograph showi Anteroposterior view of abdominal radiograph showing multiple dilated loops of a small bowel with air-fluid levels.

When a patient has GI bleeding suggestive of Meckel diverticulum, the diagnostic evaluation should focus on Meckel scanning, a technetium-99m pertechnetate scintiscan (0.2mCi/kg in children, up to the dosage used in adults, 10-20mCi in adults). The pertechnetate is taken up by heterotopic gastric mucosa. Because bleeding from the Meckel diverticulum is related to acid induced damage of mucosa adjacent to the parietal cell containing tissue, it is always included early in the work-up. [24]

After intravenous injection of the isotope, the gamma camera is used to scan the abdomen. This procedure usually lasts approximately 30 minutes. Gastric mucosa secretes the radioactive isotope; thus, if the diverticulum contains this ectopic tissue, it is recognized as a hot spot.

The Meckel scan is the preferred procedure because it is noninvasive, involves less radiation exposure, and is more accurate than an upper GI and small-bowel follow-through study.

Based on a retrospective review of Meckel scans performed from 1993-2011, the Meckel scan has a reported sensitivity of 94% and a specificity of 97% in children.

In adults, in whom GI bleeding is a much less common presentation, the scan has a lower sensitivity (62.5%), a much lower specificity (9%), and a lower accuracy (46%) [25]

Because the Meckel scan is specific for gastric mucosa (ie, in the stomach or ectopic) and not specifically diagnostic of Meckel diverticulum, false positive results occur whenever ectopic gastric mucosa is present. Duodenal ulcer, small intestinal obstruction, some intestinal duplications, ureteric obstruction, aneurysm, and angiomas of the small intestine have yielded positive results. False negative results can occur when gastric mucosa is very slight or absent in the diverticulum, if necrosis of the diverticulum has occurred, or if the Meckel is superimposed on the bladder. [26]

Accuracy of the scan may be enhanced with administration of cimetidine, glucagon, and pentagastrin. Cimetidine enhances the uptake and blocks the secretion of technetium-99m pertechnetate from ectopic gastric mucosa. [27]  This helps to improve the lesion to background ratio in enhancing a Meckel scan. Pentagastrin also enhances uptake of the isotope but also increases peristalsis, attenuating its value. Glucagon is used to decrease peristalsis, thus allowing the signal to be taken up during a longer exposure time. One strategy uses both pentagastrin and glucagon. With newer imaging technology, false-positive and false-negative rates have declined.

Barium studies have largely been replaced by other imaging techniques; however, if a barium study is indicated, it should never precede the technetium-99m scan because barium may obscure the hot spot.

A bleeding scan can be performed to identify the source if the patient is bleeding at 0.1ml/min or more. This scan involves removing and labeling some of the patient's own RBCs with technetium-99m, reinjecting them into the patient, and then scanning the abdomen for hot spots. [28, 29]

A retrospective study demonstrated that a repeat Meckel scan can be diagnostic in patients with an equivocal or negative finding who continue to have bleeding and a high clinical suspicion for Meckel diverticulum. Following an equivocal scan, 58% of the repeat scans were found to be positive, and 85% of these had a Meckel diverticulum. For patients with a negative first scan who remained with a high suspicion for Meckel diverticulum, 14% were positive on repeat study, and 86% remained negative. A repeat scan can also be helpful to differentiate a false-positive result from a true Meckel diverticulum. [30]

Selective arteriography may be helpful in patients in whom the results from scintigraphy and barium studies are negative. Usually, this occurs if the bleeding is either intermittent or has completely resolved.

When the rate of bleeding is greater than 1 mL/min, a superior mesenteric arteriogram can be helpful, but interpretation may be difficult due to overlying blood vessels. In these cases, selective catheterization of the distal ileal arteries may be needed.

Demonstration of abnormal arterial branches, dense capillary staining, or extravasation of the contrast medium confirms the presence of a Meckel diverticulum. However, a well-developed arterial supply may not always be present in the Meckel diverticulum; thus, these arteriographic signs are not very reliable.

Traditional small-bowel series using barium have been unreliable in the detection of Meckel diverticulum. However, in patients who require barium study to primarily look for other conditions, enteroclysis is more sensitive in detecting Meckel diverticulum. Enteroclysis involves using a continuous infusion of barium with adequate compression of the ileal loops and intermittent fluoroscopy to detect Meckel diverticulum. If the barium mixture is too dense and the fold pattern cannot be visualized, carboxymethylcellulose sodium can be used as the contrast medium. On barium studies, Meckel diverticulum may appear as a blind-ending pouch on the antimesenteric side of the distal ileum. If filling defects are visualized, the diverticulum may contain a tumor. Characteristic radiologic signs for Meckel diverticulum include demonstration of a triradiate fold pattern or a mucosal triangular plateau. Occasionally, a gastric rugal pattern may also be found within the Meckel diverticulum. A barium enema can be performed if intussusception is suspected. Some people have tried hydrostatic therapy to reduce intussusception, but this has not been found to be useful.

Previously, abdominal CT scanning was not considered helpful because differentiating Meckel diverticulum from the small-bowel loops is difficult. However, a blind-ending fluid-filled and/or gas-filled structure in continuity with small bowel may be visualized. CT scanning may also reveal an enterolith, intussusception, or diverticulitis. CT enterography advancements have increased the sensitivity in the diagnosis of Meckel diverticulum. [24]

A retrospective study was performed to determine the frequency of detecting symptomatic and asymptomatic Meckel diverticulum in patients known to have the lesion. A total of 85 CT examinations (23 on 14 symptomatic patients and 62 on 26 asymptomatic patients) were retrospectively reviewed after surgical resection of Meckel diverticulum. Among all 85 CT examinations, a Meckel diverticulum was detected in 34.1% of patients. In symptomatic patients, Meckel diverticulum could be seen in 57.1% on at least 1 CT examination and in 56.5% of total CT examinations. Among the 14 symptomatic patients with negative studies, 6 were children with little peritoneal fat, which likely related to the failure to see the diverticulum. In asymptomatic patients, Meckel diverticulum was detected in 42.3% patients on at least 1 CT examination and 25.8% of total CT examinations. The authors concluded that CT scan was able to detect Meckel diverticulum in 47.5% of all patients. The highest rates of success were found in symptomatic patients and in those with adequate peritoneal fat. [31]

Ultrasonography has been used in some cases of Meckel diverticulum. Ultrasonography tends to be helpful if the patient presents with anatomic rather than mucosal complications. A retrospective study analyzed ultrasound characteristics of pathologically proven Meckel diverticulum. The study concluded that Meckel diverticulum is difficult to detect by ultrasound (detection rate of 15.5%). However, the presence of complications such as intussusception (24%), intestinal obstruction (24%), and diverticulitis (15.5%) increased the rate of detection. [32]

Wireless capsule endoscopy has been successfully used to identify Meckel diverticulum in young children. [33]  In adults, this same technique has been used to identify an inverted Meckel diverticulum that presented as GI bleeding. [34]

Newer imaging modalities have been used to diagnose Meckel diverticulum. Magnetic resonance (MR) enterography was able to visualize a Meckel diverticulum in an adult who presented with GI bleeding after numerous other modalities had failed to reveal the source of bleeding.

A multidetector-row CT (MDCT) was employed to study a series of patients prior to surgery for small bowel obstruction. The images were retrospectively reviewed, and evaluated for visualization of Meckel diverticulum, complication type of Meckel diverticulum, location and grade of small bowel obstruction, and the identification of a normal appendix. [35]  The authors found that when the Meckel diverticulum is visualized on preoperative MDCT, it can be considered the likely source of the obstruction. If the obstructive process is seen in the midline location, at the terminal branch of SMA, then the Meckel diverticulum is possibly the cause of the obstruction. However, the preoperative diagnosis of Meckel cannot be made if it is not noted in MDCT. This is frequently the situation in children as the diverticulum is not as developed. Two children with obstruction, were noted to have congenital bands between the mesentery and Meckel diverticulum. [35]

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Histologic Findings

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%, and both gastric and duodenal mucosa were found in 2%. [2]

Although some reports have associated Helicobacter pylori with ectopic gastric mucosa in Meckel diverticulum, a small series of 21 consecutive patients from Turkey using polymerase chain reaction (PCR) failed to identify 23S ribosomal RNA sequences from the organism even in the 12 surgical specimens with heterotopic gastric mucosa. [36]

A retrospective case study showed Meckel diverticulum with gastric heterotopia has an increased frequency of abdominal pain, vomiting/nausea, and rectal bleeding compared with Meckel diverticulum with pancreatic heterotopia or no heterotrophic tissue. [37]

Carcinoid and gastrointestinal stromal tumors (GIST) have been found in resected specimen of perforated or symptomatic Meckel diverticulum. A case report described a case of perforated Meckel diverticulum in which histological findings revealed a GIST within the Meckel diverticulum. GISts can coexist along with other tumors. The study concluded that segmental resection of small bowel should be considered in cases of perforation due to chances of a tumor within the diverticulum. [38]

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