POCT fecal occult blood test (FOBT) is not useful for either cancer screening or gastrointestinal (GI) bleeding workup. Often the test is used ‘off-label’ in the Emergency Department (ED) to assess patients with suspected GI bleeding, iron-deficiency anemia and/or black stools. Although the test is relatively inexpensive and provides quick results, the test has poor diagnostic sensitivity and lacks clinical utility. It has a high false positive rate (e.g. red meat, beet root, NSAIDs or anti-coagulant medication) and potential for false negatives (e.g. vitamin C, time of collection). Given the absence of clinical evidence or guidelines endorsing the use of urgent screening with FOBT, it is recommended that the test be discontinued for such purposes in the ED and acute care settings.
Sources:
Canadian Agency for Drugs and Technologies in Health. Urgent, non-screening fecal occult blood testing for patients with suspected gastrointestinal bleeding: A review of clinical effectiveness and guidelines. 2017. PMID: 28727402.
Cuthbert JA, et al. Diagnostic fecal occult blood testing in hospitalized and emergency department patients: time for change? Lab Med. 2018;49(4);385–392.
Drescher MJ, et al. A call for a reconsideration of the use of fecal occult blood testing in emergency medicine. J Emerg Med. 2020;58(1):54-58. PMID: 31926780.
Lee MW, et al. Use of fecal occult blood testing as a diagnostic tool for clinical indications: A systematic review and meta-analysis. Am J Gastroenterol. 2020;115(5):662-670. PMID: 31972617.