Gastrointestinal Bleeding in Adult Patients With Meckel's Divert
Gastrointestinal Bleeding in Adult Patients With Meckel's Divert
Obscure gastrointestinal (GI) bleeding is often challenging for the primary care physician, but with improved diagnostic testing the cause of this blood loss is determined in most patients. However, approximately 5% of the time no underlying cause is found. One common etiology in patients younger than 40 years of age is a Meckel's diverticulum. The technetium 99m pertechnetate scan is the standard test for making this diagnosis. However, the sensitivity of the scan is only 62% in the adult population. In this case report, a patient with profound, hemodynamically significant GI blood loss had multiple negative studies. Subsequently, an abnormal vascular lesion was detected and during exploratory laparotomy, a Meckel's diverticulum was found and removed. Although the technetium pertechnetate scan is falsely negative in a number of cases, there are ways to increase its sensitivity and possibly avoid repeated testing.
In about 5% of cases of gastrointestinal (GI) hemorrhage, the source of bleeding is not identifiable, and patients are often subjected to extensive and repetitive testing, including upper endoscopy, colonoscopy, and upper GI series (with contrast medium). When these initial studies are negative, further investigation includes scintigraphy with labeled red blood cells (RBCs), arteriography, technetium 99m pertechnetate (Meckel's) scan, enteroclysis, and/or small bowel enteroscopy. In patients more than 40 years old, vascular ectasias, Dieulafoy lesions, injury due to nonsteroidal anti-inflammatory drugs (NSAIDs), and cancer are the common causes. In patients younger than 40, however, small bowel cancer, Meckel's diverticulum, polyposis syndrome, and Crohn's disease are often found.
Meckel's diverticulum, a vestige of the omphalomesenteric duct, is the most common congenital GI anomaly, causing nearly 50% of all cases of lower GI bleeding in patients less than 3 years of age. This anomaly represents a true diverticulum and may contain heterotopic gastric tissue. The presence of gastric mucosa in the diverticulum increases the risk of GI hemorrhage. The German anatomist Johann Friedrich Meckel meticulously described this entity in the 19th century. The technetium 99m pertechnetate scan is the test of choice for detecting Meckel's diverticulum, with a reported sensitivity of 85% to 90% in the pediatric population. In adults, however, the sensitivity falls to only 62%. False-negative studies may be due to improper technique, pooling of the radioactive material in the stomach or bladder, or a paucity of ectopic gastric mucosa. Several modifications that may be used to improve this diagnostic yield are premedication with histamine receptor antagonist with or without pentagastrin, bladder lavage, and nasogastric suctioning. Recently, a modification of the standard Meckel's scan using single photon emission computed tomography (SPECT) has been shown to detect heterotopic gastric mucosa. However, the sensitivity and specificity of this technique in the diagnosis of Meckel's diverticulum has not been reported. This case report of GI blood loss in a patient who had a false-negative Meckel's scan illustrates the need to pursue modifications in technetium pertechnetate scans to minimize false-negative results.
Obscure gastrointestinal (GI) bleeding is often challenging for the primary care physician, but with improved diagnostic testing the cause of this blood loss is determined in most patients. However, approximately 5% of the time no underlying cause is found. One common etiology in patients younger than 40 years of age is a Meckel's diverticulum. The technetium 99m pertechnetate scan is the standard test for making this diagnosis. However, the sensitivity of the scan is only 62% in the adult population. In this case report, a patient with profound, hemodynamically significant GI blood loss had multiple negative studies. Subsequently, an abnormal vascular lesion was detected and during exploratory laparotomy, a Meckel's diverticulum was found and removed. Although the technetium pertechnetate scan is falsely negative in a number of cases, there are ways to increase its sensitivity and possibly avoid repeated testing.
In about 5% of cases of gastrointestinal (GI) hemorrhage, the source of bleeding is not identifiable, and patients are often subjected to extensive and repetitive testing, including upper endoscopy, colonoscopy, and upper GI series (with contrast medium). When these initial studies are negative, further investigation includes scintigraphy with labeled red blood cells (RBCs), arteriography, technetium 99m pertechnetate (Meckel's) scan, enteroclysis, and/or small bowel enteroscopy. In patients more than 40 years old, vascular ectasias, Dieulafoy lesions, injury due to nonsteroidal anti-inflammatory drugs (NSAIDs), and cancer are the common causes. In patients younger than 40, however, small bowel cancer, Meckel's diverticulum, polyposis syndrome, and Crohn's disease are often found.
Meckel's diverticulum, a vestige of the omphalomesenteric duct, is the most common congenital GI anomaly, causing nearly 50% of all cases of lower GI bleeding in patients less than 3 years of age. This anomaly represents a true diverticulum and may contain heterotopic gastric tissue. The presence of gastric mucosa in the diverticulum increases the risk of GI hemorrhage. The German anatomist Johann Friedrich Meckel meticulously described this entity in the 19th century. The technetium 99m pertechnetate scan is the test of choice for detecting Meckel's diverticulum, with a reported sensitivity of 85% to 90% in the pediatric population. In adults, however, the sensitivity falls to only 62%. False-negative studies may be due to improper technique, pooling of the radioactive material in the stomach or bladder, or a paucity of ectopic gastric mucosa. Several modifications that may be used to improve this diagnostic yield are premedication with histamine receptor antagonist with or without pentagastrin, bladder lavage, and nasogastric suctioning. Recently, a modification of the standard Meckel's scan using single photon emission computed tomography (SPECT) has been shown to detect heterotopic gastric mucosa. However, the sensitivity and specificity of this technique in the diagnosis of Meckel's diverticulum has not been reported. This case report of GI blood loss in a patient who had a false-negative Meckel's scan illustrates the need to pursue modifications in technetium pertechnetate scans to minimize false-negative results.
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