Pediatric Meckel Diverticulum Workup

Updated: Nov 19, 2020
  • Author: Simon S Rabinowitz, MD, PhD, FAAP; Chief Editor: Carmen Cuffari, MD  more...
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Workup

Approach Considerations

The history and physical examination are of paramount importance for establishing a clinical diagnosis of Meckel diverticulum. Perform a rapid assessment of any child with significant bleeding or signs of small bowel obstruction, ischemia, or inflammation. Meckel diverticulum is a relatively uncommon etiology for any of these complications, but it must always be considered in the differential diagnosis.

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Laboratory Studies

Routine laboratory findings, including a complete blood cell (CBC) count, electrolyte levels, glucose, blood urea nitrogen (BUN), creatinine levels, and coagulation screen results, are not helpful in establishing the diagnosis of Meckel diverticulum, but they are necessary to manage a patient with gastrointestinal bleeding along with a blood type and cross-match.

Hemoglobin and hematocrit levels are low in the setting of anemia or significant bleeding. In one series, 58% of children had average hemoglobin levels lower than 8.8 g/dL.

In a prospective linear observational study of 73 children with a diagnosis of symptomatic Meckel diverticulum that compared mean hemoglobin level before onset of symptoms and at presentation of rectal bleeding, there was a 58% correlation between Meckel diverticulum and hematochezia with a drop in hemoglobin of more than 2 g/dL. [31]

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 chronic dilatation and/or stasis related to the diverticulum is present. Low albumin and low ferritin levels may erroneously lead to a diagnosis of inflammatory bowel disease.

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Imaging Studies

According to the Mayo Clinic, "Meckel's diverticulum is frequently suspected, often looked for, and seldom found." [32] Preoperative diagnosis is difficult, especially if the presenting symptom is not gastrointestinal (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. [32]

Imaging studies are performed to confirm a clinical suspicion of Meckel diverticulum.

Radiography

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.

Pediatric Meckel Diverticulum. Anteroposterior vie Pediatric Meckel Diverticulum. Anteroposterior view of an abdominal radiograph showing multiple dilated loops of a small bowel with air-fluid levels.

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 (99m-Tc pertechnetate scintigraphy; Meckel scan) (see below), because barium may obscure the hot spot.

Traditional small-bowel series using barium have been unreliable in the detection of Meckel diverticulum. However, for patients who require a 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.

Meckel scan

When a patient has GI bleeding suggestive of Meckel diverticulum, the diagnostic evaluation should focus on the "Meckel scan," a 99m-Tc pertechnetate scintiscan (0.25 mCi/kg in children, up to the dosage used in adults; 8-12 mCi in adults). [2] The Meckel scan is the preferred modality, because it is noninvasive, involves less radiation exposure, and is more accurate than an upper GI and small-bowel follow-through study. 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. [33]

After intravenous injection of the isotope, a gamma camera is used to scan the abdomen. This procedure usually lasts approximately 30 minutes. [2] Gastric mucosa secretes the radioactive isotope; thus, if the diverticulum contains this ectopic tissue, it is recognized as a hot spot.

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. [34] 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%). [35]

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 diverticulum is superimposed on the bladder. [36]

Accuracy of the scan may be enhanced with administration of cimetidine, glucagon, and pentagastrin. Cimetidine enhances the uptake and blocks the secretion of 99m-Tc pertechnetate from ectopic gastric mucosa, [37]  which 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.

Bleeding scan

A bleeding scan can be performed to identify the source if the patient is bleeding at 0.1 mL/min or more. The scan involves removing and labeling some of the patient's own red blood cells 99m-Tc, reinjecting them into the patient, and then scanning the abdomen for hot spots. [38, 39]

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. [40] 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 with a persistent 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. [40]

Arteriography

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.

Computed tomography (CT) scanning

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. [33]

In a retrospective study to determine the frequency of detecting symptomatic and asymptomatic Meckel diverticulum in patients known to have the lesion, comprising a total of 85 CT examinations (23 on 14 symptomatic patients and 62 on 26 asymptomatic patients) after surgical resection of Meckel diverticulum, a Meckel diverticulum was detected in 34.1% of patients. [41] In symptomatic patients, Meckel diverticulum could be seen in 57.1% of patients on at least one CT examination and in 56.5% of the total CT examinations. Among the 14 symptomatic patients with negative studies, 6 involved 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 one CT examination and 25.8% of the total CT examinations. The authors concluded that CT scanning 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. [41]

Ultrasonography

Ultrasonography has been used in some cases of Meckel diverticulum. This modality tends to be helpful if the patient presents with anatomic rather than mucosal complications. A retrospective study that analyzed ultrasound characteristics of pathologically proven Meckel diverticulum concluded that this condition is difficult to detect by ultrasound (detection rate of 15.5%). [42] However, the presence of complications such as intussusception (24%), intestinal obstruction (24%), and diverticulitis (15.5%) increased the rate of detection.

Capsule endoscopy

Capsule endoscopy is a relatively new technology that assists with imaging in the small intestine . Wireless capsule endoscopy has been successfully used to identify Meckel diverticulum in young children and adolescents [43, 44]  especially after endoscopy and colonoscopy failed to detect the site of bleeding. Features that are noted include two lumina, a thickened bridge, an ulcer and, occasionally, direct visualization of ectopic gastric mucosa. However, during active bleeding, the diverticulum itself may be missed, lowering its sensitivity in those circumstances. In adults, this same technique has been used to identify an inverted Meckel diverticulum that presented as GI bleeding. [45]

Other imaging studies

Magnetic resonance imaging (MRI)

Newer imaging modalities have been used to diagnose Meckel diverticulum. Magnetic resonance (MR) enterography (MRE) 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. MRI of another case revealed a cystlike structure of the small intestine in the iliac fossa with high signal intensity. [46] This cystlike structure had a tear drop shape in the nonenhanced T1-weighted spin-echo coronal image, suggesting that it was a blood-filled body.

MR imaging can also be used to detect inflamed Meckel diverticulum, which is especially attractive for pediatric patients due to the lack of ionizing radiation. [46]

Multidetector-row CT (MDCT) scanning

In a retrospective study that used MDCT scanning evaluate a series of patients prior to surgery for small bowel obstruction for factors such visualization of Meckel diverticulum, complication type of Meckel diverticulum, location and grade of small bowel obstruction, and the identification of a normal appendix, the authors found that when the Meckel diverticulum was visualized on preoperative MDCT scanning, it could be considered the likely source of the obstruction. [47] If the obstructive process was seen in the midline location, at the terminal branch of the superior mesenteric artery, then the Meckel diverticulum was possibly the cause of the obstruction. However, the preoperative diagnosis of Meckel could not be made if it was not noted in MDCT scanning; 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. [47]

Single-photon emission tomography/CT (SPECT/CT) scanning

Ambiguous results of a Meckel scan have recently been clarified with hybrid SPECT/CT scanning. SPECT/CT scanning enhances the sensitivity of a Meckel scan by precisely localizing ectopic gastric mucosa at an abnormal anatomic structure, while decreasing the false-negative or false-positive results associated with a traditional Meckel scan. Because of increased radiation, its greatest value may be in complicated situations.

In a case report that employed SPECT/CT fusion imaging after a CT scan showed an irregular inflammatory lesion believed to be an abscess in the distal ileum with a normal appendix, 99m-Tc pertechnetate scintigraphy was performed after the intravenous injection of 370 MBq 99m-Tc pertechnetate. [48]  Dynamic (2 min/frame) and delayed (30 min, 60 min) images revealed the focal concentration to be under the liver, similar to the gastric uptake. SPECT/CT fusion imaging clarified that the focal concentration was in the distal ileum, surrounded by the inflammatory lesion. [48] Thus, in the face of complications related to a Meckel diverticulum, SPECT/CT fusion imaging can enhance the preoperative findings. 

A 3-year-old girl was diagnosed with Meckel diverticulum by planar scintigraphy; due to resolution of her symptoms and concomitant congenital heart disease, surgery was not performed at the time. [49] She presented 7 years later with massive hematochezia; a repeat planar scintigraphy showed an uptake in the area of the kidney. Whether this was due to physiologic uptake by the kidney or by ectopic gastric mucosa is unclear. A SPECT/CT scan was able to confirm that the Meckel diverticulum was the exact anatomic site of the focal concentration. [49]

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Histologic Findings

The surgical and oncologic relevance of Meckel diverticulum comes from its pluripotent cell lining. 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%. [3]

Rarely, ectopic tissue may undergo malignant degeneration; consequently, because the wall of the diverticulum is thin, a small cancer can penetrate and widely metastasize within the peritoneal space. In a case report, the immunohistochemical profile of the tumor cells, along with the presence of gastric epithelial differentiation, favored its origin in ectopic gastric epithelium. [50]  Per the authors’ report at the time, this was the first patient with gastric cancer peritoneal metastases reported in the literature and successfully treated.

GISTs can coexist along with other tumors. Carcinoid, pancreatic, 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 histologic findings revealed a GIST within the Meckel diverticulum. [51] The study concluded that segmental resection of the small bowel should be considered in cases of perforation due to the risks of a tumor within the diverticulum.

Helicobacter pylori is a gram-negative rod that has virulence factors, allowing them to survive in the mucus layer adherent to gastric epithelium. The presence of H pylori in a heterotopic gastric mucosa in a Meckel diverticulum has not been widely reported, and its actual prevalence may vary. In a review of the literature for both adult and pediatric cases, a 2% prevalence of H pylori was noted in heterotopic gastric mucosa. [52] The authors thus proposed considering an addition to the “rule of twos” related to Meckel diverticulum. In contrast, a small series of 21 consecutive patients from Turkey using polymerase chain reaction (PCR) failed to identify 23S ribosomal RNA sequences from the organism in their 12 surgical specimens with heterotopic gastric mucosa. [53]

Although the underlying mechanisms leading to the rarely described perforated Meckel diverticulum in neonates have not been fully elucidated, it is thought that ectopic mucosa appeared to have little association with the development of perforation in these patients. Previous studies suggested that bowel obstruction was the most common etiology resulting in perforated Meckel diverticulum in term infants. High pressure within a thin diverticulum was hypothesized to play a vital role in the development of perforation in the neonatal period. [54, 55]  However, a small case series describing five neonates with perforation in a Meckel diverticulum demonstrated extensive inflammation without ectopic mucosa and gangrenous inflammation. [56] The authors of the series proposed that hypoxia, inadequate blood supply, intestinal permeability, and early use of postnatal steroid and indomethacin can increase the risk of spontaneous intestinal perforation. [56]

Like the authors of the small series above who inferred that the perforation may be related to intestinal immaturity, the authors of this article agree that in premature infants and neonates, conditions could lead to a necrotizing enterocolitis event that is centered in the Meckel diverticulum in a vulnerable patient. Another small case series that described seven cases of neonatal perforated Meckel diverticulum found heterotopic mucosa in just two cases and no evidence of intrinsic bowel wall weakness. [57]

In another case report, an inverted Meckel diverticulum contained several aberrant smooth muscle bundles. [58]  The investigators proposed that these muscle bundles may have produced abnormal peristaltic movement, acting as a lead point for the inversion and ileoileal intussusception.

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 heterotophic tissue. [59]

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