A Case of Obscure Gastrointestinal Bleeding Secondary to a Small Bowel Gastrointestinal Stromal Tumor Detected by Magnetic Resonance Enterography

Introduction

Obscure gastrointestinal (GI) bleeding creates a diagnostic challenge for gastroenterologists. Many patients undergo multiple blood transfusions and repeated studies. Modern imaging techniques improve detection and characterization of small bowel tumors and provide important guidance for treatment options. We present a case of obscure GI bleeding secondary to a small bowel tumor that was detected by magnetic resonance enterography (MRE).

Case Report

A 28-year-old woman presented to the emergency department with a chief symptom of fatigue. She denied abdominal pain, hematochezia, and melena and use of nonsteroidal anti-inflammatory drugs. Her medical history was unremarkable. Her abdomen was unremarkable, revealing no abnormalities on percussion and palpation. Rectal examination revealed no gross blood, but fecal testing was positive for occult blood. Initial laboratory values indicated a hemoglobin level of 3.8 (reference range, 12-16 g/dL). A review of her medical records showed that she had had computed tomography (CT) of the abdomen and pelvis a few weeks before presentation for the abdominal discomfort. Findings were negative. The patient had a blood transfusion and was admitted for further diagnostic evaluation. Upper endoscopy and colonoscopy with ileal intubation failed to reveal a bleeding source. Video capsule endoscopy (VCE) performed within 24 hours of admission showed red blood in the small intestinal lumen within 5 hours of swallowing the capsule, but no definitive source of active bleeding in the small bowel was identified. She subsequently had a Meckel's scan and a red blood cell scintigraphy scan; both of which were negative. Her hemoglobin level remained stable after the initial transfusion, and she was discharged on iron supplementation with close outpatient follow-up. Two weeks after discharge, repeated VCE was done to re-evaluate the small intestine. No blood was seen, and no potential bleeding lesions were identified.

The patient returned to the emergency department several months later with symptomatic anemia. Her hemoglobin level at this time was 8.5 g/dL. She was again admitted for resuscitation and diagnostic evaluation. During this admission, MRE was performed (Figures 1 and 2) and revealed a 2.9-cm x 3-cm distal jejunal wall mass.

Although it had an intraluminal component, the mass was predominantly extramural. The patient was subsequently referred for surgical evaluation and had a successful laparoscopic resection of the tumor (Figure 3).

The specimen contained spindle cells that stained strongly for C-117 (c-kit), consistent with a diagnosis of GI stromal tumor (Figure 4).

Discussion

Evaluation of obscure GI bleeding can be a challenge for the gastroenterologist, as illustrated by this case. Most lesions responsible for obscure GI bleeding arise from the small bowel, which has been considered uncharted territory for many years.^[1,2] Its extensive length, vigorous contractility, and free intraperitoneal location make diagnosis of bleeding in this area difficult.^[3]

VCE and double-balloon enteroscopy have revolutionized diagnostic evaluation of the small bowel. However, before their availability, imaging studies were the mainstay in the initial evaluation of the small bowel in patients presenting with obscure GI bleeding.^[4] Because most of these cases are secondary to flat vascular ectasias,^[1,2,3,4] the diagnostic yield of barium studies is low.^[3,4] The yield of small bowel follow-through is approximately 5%^[5] in obscure GI bleeding, and enteroclysis offers only slightly better detection rates.^[6] One study suggested that helical CT may have a role in the evaluation of obscure GI bleeding and is reported to detect a cause in 11 of 18 patients (61%).^[7] A wide variety of causes were confirmed on laparoscopy and endoscopy, including angiectasias, benign tumors, and one case of pancreatic cancer. Finally, radionuclide scintigraphy and angiography have a role for cases in which brisk bleeding is present, but many cases of obscure GI bleeding are characterized by intermittent bleeding, especially in the setting of volume contraction and anemia.

Small bowel tumors, followed by Meckel's diverticulum, are the most common cause of obscure GI bleeding in patients under the age of 40.^[4] While intraluminal extension of small bowel tumors may cause symptoms of obstruction, it is important to recognize that such tumors may also extend extraluminally into the peritoneum. Intermittent hemorrhage through small ulcerations or erosions through the bowel wall may result in missed lesions on VCE, as noted in our case. Additionally, they may not be within reach of a video enteroscope.

MRE is an emerging diagnostic tool that is being used more frequently in evaluation of patients with Crohn's disease, especially for detection and staging of fistulas.^[8,9] The examination consists of administration of a neutral oral contrast followed by high-spatial resolution imaging through the abdomen and pelvis. It has many unique properties and advantages over other imaging modalities -- for example, it yields additional information because of the soft-tissue contrast capability, multiplanar cuts, and the ability to perform real-time cine imaging; it also does not expose the patient to ionizing radiation. Adequate visualization of the entire small bowel wall is made possible through mural enhancement and stratification.^[8,9] Because of the additional diagnostic options inherent in the procedure, MRE can be a valuable tool to identify mass lesions that may have been missed by VCE. Some limitations of its use, however, include availability of MR scanners, lack of experience with technique and image reading, and high cost.

Conclusion

Due to the relative inaccessibility of the small bowel, diagnosis of obscure GI bleeding remains a challenge. Advances in imaging techniques of the small bowel allow us to better evaluate areas that have previously been poorly visualized. MRE may have a role in the evaluation of patients presenting with obscure GI bleeding and should be considered as a diagnostic option in the assessment of such patients, especially in those younger than 40 years in whom no source can be clearly identified. Clinicians should consider its use as a complementary diagnostic option to VCE in the evaluation of obscure GI bleeding.

 

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Acknowledgments

The opinions are solely those of the authors and do not represent an endorsement by the Department of Defense. This is a U.S. Government work. There are no restrictions on its use. There are no conflicts of interest, financial disclosures, grant support, or writing assistance. The authors do not have any commercial or proprietary interest in any drug, device, or equipment mentioned in this article.

Medscape J Med. 2008;10(11):263 © 2008  Medscape

Cite this: A Case of Obscure Gastrointestinal Bleeding Secondary to a Small Bowel Gastrointestinal Stromal Tumor Detected by Magnetic Resonance Enterography - Medscape - Nov 18, 2008.