Time to Ban Inpatient Fecal Occult Blood Testing
Randomized, controlled trials have convincingly shown that the mortality rate of colorectal cancer can be reduced 15 to 35% by screening with fecal occult blood tests (FOBT). As a result of these studies, major professional organizations such as the American Cancer Society, the United States Preventative Service Task Force, the American College of Physicians, and the College of American Pathologists recommend annual testing of all adults at 50 years of age or older.
Besides outpatient screening for colorectal cancer, physicians commonly use FOBT in the evaluation of anemia and GI bleeding even though it is not recommended for this purpose. Evaluation of confirmed iron deficiency anemia, in the absence of other etiologies such as menorrhagia or decreased oral intake, involves endoscopic evaluation of the upper and lower GI tract. The evaluation of a suspected GI bleed begins with distinguishing upper from lower source by medical history and physical examination including digital rectal exam. Upper GI bleed is suggested by history of melena, melena detected during digital rectal examination, nasogastric lavage with blood or coffee-ground emesis and a plasma BUN to creatinine ratio greater than 30. Hematochezia or maroon colored stools suggest a lower GI bleed. Upper GI bleeds usually require endoscopic evaluation while lower GI bleeds require colonoscopy or sigmoidoscopy. The decision to perform endoscopy should not be based on the results of FOBT because of its 10 to 15% false positive rate and 30 to 50% false negative rate. False negative results can lead to inappropriate delays in endoscopy, and false positive results can lead to unnecessary endoscopy.
For these reasons, gastroenterologists at the University of Texas Southwestern Medical Center have abolished inpatient FOBT. FOBT should be restricted to the outpatient setting for colorectal screening.
References
Bangaru S, Tang D, and Agrawal D. Inappropriate use of fecal occult blood testing. JAMA, published online October 15, 2018. doi:10.1001/jamainternmed.2018.5553
Gupta A, Tang Z, Agrawal D. Eliminating in-hospital fecal occult blood testing: our experience with disinvestment. Am J Med. 2018;131 (7):760-763. doi:10.1016/j.amjmed.2018.03.002
