Don’t order this blood tests in your ED

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Fecal occult blood tests aren’t appropriate for gastrointestinal bleeding

Fecal occult blood tests (FOBT) are useless tests to order in the emergency department (ED) for the workup of gastrointestinal bleeding (GIB). FOBT has only been approved for the use of screening for colorectal cancer (CRC) and is frequently used “off-label” in the ED for the evaluation of a patient presenting with GIB. (1)

It is a waste of time, and resources, and is an unnecessary cost to the patient. This is due to the test having a very low sensitivity, not on the list of recommended studies to order, and the results should not change your management of the patient.


The sensitivity for FOBT is low and not a good screening test for GIB. One study found the sensitivity of FOBT for iron deficiency anemia to be extremely low at 0.58. (1) This would mean that 42% of patients with a clinically significant finding on endoscopy for their cause of IDA would have a negative FOBT result.

This percentage of false positives is much too high to be of use as a screening tool for GIB and could cause false reassurance to the ordering clinician. If a patient is stating they have had GI bleeding, the clinician should work this up even if the test is negative. One distributor for FOBT recommends a very specific diet to ensure there are no false positives as well, such as limiting vitamin C intake. (2,3) This obviously cannot be obtained while in the ED.

The results of the FOBT should not affect your management of the patient at all. Another study found that regardless of if the FOBT was positive or negative in the ED, it did not change the management of the patient with overt GIB. Patients with a negative FOBT were just as likely to receive gastroenterology consultation and endoscopic evaluation. (4)


This should make sense. Even if you have a negative result if the patient reports a history of GIB, they should still have a gastroenterology consultation and workup, whether during admission or outpatient. Whether the patient requires admission is obviously up to the clinician but the results of the FOBT should not be involved in your reasoning for this decision.

If you follow the approach to acute lower GIB from UpToDate and the American College of Gastroenterology, the only laboratory testing they recommend is a complete blood count, serum chemistries, liver function tests, and coagulation studies (6). This is because the goal in initial management is to attempt to locate where the bleeding is coming from and how severe the bleeding is.

There is no need to “confirm” if a patient is bleeding with a fecal occult at the time of presentation. Ultimately, depending on the severity of the bleed the patient will either require inpatient admission for colonoscopy/endoscopy or outpatient follow-up for the same testing, done on an elective basis.

Overall, clinicians have been using the FOBT inappropriately in the ED for the management of GIB. The test has not been approved for such use, the sensitivity of the test is poor, the results do not affect the management of the patient, and it is not included in the guidelines for the workup of GIB. These tests are just an additional cost to the patient and waste time and resources in the ED. So, please stop ordering these tests and follow the appropriate guidelines for the initial management of GIB.



  1. Lee MW, Pourmorady JS, Laine L. Use of Fecal Occult Blood Testing as a Diagnostic Tool for Clinical Indications: A Systematic Review and Meta-Analysis. Am J Gastroenterol. 2020 May;115(5):662-670. doi: 10.14309/ajg.0000000000000495. PMID: 31972617.
  2. Pignone M, Campbell MK, Carr C, Phillips C. Meta-analysis of dietary restriction during fecal occult blood testing. Eff Clin Pract 2001; 4:150.
  3. Jaffe RM, Kasten B, Young DS, MacLowry JD. False-negative stool occult blood tests caused by ingestion of ascorbic acid (vitamin C). Ann Intern Med 1975; 83:824.
  4. Drescher MJ, Stapleton S, Britstone Z, Fried J, Smally AJ. A Call for a Reconsideration of the Use of Fecal Occult Blood Testing in Emergency Medicine. J Emerg Med. 2020 Jan 8:S0736-4679(19)30809-1. doi: 10.1016/j.jemermed.2019.09.026. Epub ahead of print. PMID: 31926780.
  5. Strate LL, Gralnek IM. ACG Clinical Guideline: Management of Patients With Acute Lower Gastrointestinal Bleeding. Am J Gastroenterol. 2016 Apr;111(4):459-74. doi: 10.1038/ajg.2016.41. Epub 2016 Mar 1. Erratum in: Am J Gastroenterol. 2016 May;111(5):755. PMID: 26925883; PMCID: PMC5099081.



Shannon Caliri, DO, is a resident doctor at AdventHealth in Orlando, FL.

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