Review Question - QID 106153

A patient who is suspected of having a lower GI bleed which could not be localized with colonoscopy may undergo technetium-99 labelled erythrocyte scintigraphy in order to localize the lesion.

Lower GI bleeds can have many different causes, including diverticular disease, AV malformations, neoplasms, Crohn's disease, ulcerative colitis, among others. While melena may be seen, hematochezia is more commonly seen in lower GI bleeds. These patients should be evaluated for upper GI bleeds with NG lavage or upper endoscopy. Lower GI bleeds may be evaluated with anoscopy, sigmoidoscopy, or colonoscopy. Further workup may include angiography and tagged-RBC studies.

Manning-Dimmitt et al. review the evaluation of gastrointestinal bleeding in adults. Esophagogastroduodenoscopy (EGD) is useful in the evaluation of upper gastrointestinal bleeds, while colonscopy is utilized in the diagnosis of lower GI bleeds. When a upper GI or large bowel bleed cannot be identified, other modalities can be utilized to evaluate the small bowel, including arteriography, technetium-99m–tagged red blood cell scan, Meckel’s scan, enteroclysis, or upper GI series with small bowel follow through.

Allen and Tulchinsky review the use of nuclear medicine scans in the diagnosis of lower GI bleeds. They state that scintigraphy is a useful tool to localize the site of an acute lower GI bleed and helps to differentiate the need for aggressive therapy or medical management. They also state that single photon emission computed tomography/computed tomography scintigraphy can also provide important anatomical information that could impact the treatment of the patient with lower GI bleeding.

Incorrect Answers:
Answer 1: Nasogastric tube lavage is useful in evaluating for upper GI bleeding; however, it is unlikely to provide information not already available from an EGD. Furthermore, it would not be useful in localizing a lower GI bleed.
Answer 3: Ultrasound of the abdomen may provide information about whether the patient is having an intra-abdominal bleed; however, it would not be useful in localizing a lower GI bleed.
Answer 4: CT of the abdomen would not be able to provide accurate information regarding the location of a lower GI bleed.
Answer 5: Flexible sigmoidoscopy is useful in evaluating the rectum and sigmoid colon; however, it is unlikely to provide more information than a colonoscopy.