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. 2021 Aug;5(3):320-324.
doi: 10.5811/cpcem.2021.4.51656.

The Case of the Lime-green Stool: A Case Report and Review of Occult Blood Testing in the Emergency Department

James D Salisbury  1 , Jennifer G Goodrich  1 , Nicholas M McManus  1 , Ryan P Offman  1
Affiliations

The Case of the Lime-green Stool: A Case Report and Review of Occult Blood Testing in the Emergency Department

James D Salisbury et al. Clin Pract Cases Emerg Med. 2021 Aug.

Abstract

Introduction: Food dyes mimicking gastrointestinal (GI) hemorrhage have been described in literature. However, reports of food additives causing melanotic stools and falsely positive fecal occult blood tests (FOBT) are uncommon in literature.

Case report: We present a case of a 93-year-old with FOBT positive melanotic stool, felt to be falsely positive due to food additives.

Conclusion: Evaluation for GI bleeding accounts for 0.3% of yearly visits to the emergency department (ED). While FOBT is commonly used, its clinical validity in the ED is not supported by guidelines. We showcase the limitations of the FOBT and review the causes of false positive FOBT.

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Conflict of interest statement

Conflicts of Interest: By the CPC-EM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. The authors disclosed none.

Figures

Image 1
Image 1
Artifical food coloring emulsified with a burger bun and water (left). Sample of this mixture tested on a guaiac fecal occult blood test (right).
Image 2
Image 2
Weak solution of artifical food coloring emulsified with water (left). Sample of this mixture tested on a guaiac fecal occult blood test card (right).
See this image and copyright information in PMC

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