>Decisions: A 20-year-old male with dark stool

Medical Student Clinical Pearl – January 2019

Lucy Eum – Med I Class of 2021, Dalhousie Medicine New Brunswick 

Reviewed and Edited by Dr. David Lewis


Case

A 20-year-old African male presented to the emergency department with black, tarry stool for the past two days. He appeared hemodynamically stable. He was treated for peptic ulcer disease (PUD) due to Helicobacter pylori infection eight months ago after an episode of severe hemorrhage. His medications included ferrous sulfate and Pepto-Bismol. He did not have a primary care provider.

What diagnoses should be considered?

90% of melena is due to upper gastrointestinal (GI) hemorrhage proximal to the ligament of Treitz, but the pharynx and small bowel may sometimes be involved.2 Major causes of upper GI bleeding include PUD, varices, Mallory-Weiss tear, or neoplasms.1 Life-threatening hemorrhage, varices, ulcerations, arteriovenous malformations, and malignancy must also be considered.1

It is important to distinguish between dark stool from blood, known as melena, and dark stool from other causes, such as iron or bismuth. Liquid consistency, shininess, and foul smell are distinct features of melena. 5

What questions should this patient be asked?

Symptoms can help determine the severity and etiology.1 Upper abdominal pain is common with peptic ulcer. Dysphagia combined with weight loss and early satiety is characteristic of malignancy. Significant coughing or retching may lead to Mallory-Weiss tear.2

Comorbidities and prior episodes of upper GI bleeding should be asked. History of liver disease and alcoholism are associated with variceal hemorrhage. Abdominal aortic aneurysm is associated with an aortoenteric fistula. A history of H. pylori infection and NSAID use are risk factors for PUD.2

The use of NSAIDs, antiplatelets, or anticoagulants must be identified. Medications that can induce pill esophagitis (i.e. bisphosphonates) also need to be identified. Bismuth and iron can both lead to harmless darkening of the stool.2

Are any investigations required?

Physical exam begins with an assessment of the patient’s hemodynamic stability.2 Signs of any co-morbidities should be noted. Laboratory tests should include complete blood count, liver function tests, and serum electrolytes. The hemoglobin level may be unchanged from baseline for the first 24 hours.1

Is fecal occult blood test required?

The FOBT has only been validated for use in asymptomatic patients for colorectal cancer (CRC) screening.5 For symptomatic (i.e. melena) patients with high pre-test probability of GI bleeding, the FOBT has a high false positive rate.5

Foods with peroxidase activity (i.e. red meat), vitamin C, antiplatelets and anticoagulants can influence the FOBT results,5 therefore dietary and medication restriction for three days is needed.3 Therefore, the FOBT is unsuitable for emergency rooms despite common use in this setting as a point-of-care (POC) test.3 The newer immunochemical FOBTs do not require dietary restriction and have shown improved accuracy as POC testing for CRC, but its accuracy in evaluating black-coloured stools remains unclear.3, 7

There is speculation that FOBT may be used for patients with dark stools on iron supplementation.3 However, melena is usually well-characterized by its liquid consistency, shininess, and foul smell. Importantly, the FOBT has never been validated for such use to distinguish between melena and other causes of dark stool.3, 5

How should this patient be managed?

A hemodynamically stable patient should be promptly categorized according to rebleeding and mortality risk, using the Glasgow Blatchford Score (GBS) or Rockall Score. They are validated tools based on information such as the patient’s blood pressure, hemoglobin level, and co-morbidities.4, 6

Although pre-endoscopic empiric therapy with PPI is recommended for all patients, this is based on the excellent safety profile of PPIs rather than evidence regarding their efficacy.4 Histamine-2 receptor antagonists are ineffective as preendoscopic therapy.4, 6

Endoscopy within the first 24 hours of presentation is recommended for suspected GI bleeding,1,4 although patients with very low GBS Score (i.e. zero) are unlikely to benefit.5

Generally, all patients with upper GI bleeding require gastroenterology consult. In cases where endoscopy is not suitable, surgical consultation is needed.2

Case revisited

Physical exam and lab results were unremarkable except low hemoglobin, which yielded a total GBS Score of 2 for this patient. Since this is considered high risk1, gastroenterology was consulted. The patient was given an infusion of IV PPI.

Although the patient is on iron and bismuth, he had been on these medications for many months, and, given his history of severe hemorrhage due to PUD without a family physician to provide follow-up care, it was deemed appropriate to investigate further.


References

1. Kim B, Li B, Engel A, Samra J, Clarke S, Norton I et al. Diagnosis of gastrointestinal bleeding: A practical guide for clinicians. World Journal of Gastrointestinal Pathophysiology. 2014;5(4):467.

2. Cappell M, Friedel D. Initial Management of Acute Upper Gastrointestinal Bleeding: From Initial Evaluation up to Gastrointestinal Endoscopy. Medical Clinics of North America. 2008;92(3):491-509.

3. Ip S, Sokoro A, Buchel A, Wirtzfeld D, Konrad G, Fatoye T et al. Use of Fecal Occult Blood Test in Hospitalized Patients: Survey of Physicians Practicing in a Large Central Canadian Health Region and Canadian Gastroenterologists. Canadian Journal of Gastroenterology. 2013;27(12):711-716.

4. Barkun A, Fallone C, Chiba N, Fishman M, Flook N, Martin J et al. A Canadian Clinical Practice Algorithm for the Management of Patients with Non-Variceal Upper Gastrointestinal Bleeding. Canadian Journal of Gastroenterology. 2004;18(10):605-609.

5. Narula N, Ulic D, Al-Dabbagh R, Ibrahim A, Mansour M, Balion C et al. Fecal Occult Blood Testing as a Diagnostic Test in Symptomatic Patients is not Useful: A Retrospective Chart Review. Canadian Journal of Gastroenterology and Hepatology. 2014;28(8):421-426.

6. Barkun A. International Consensus Recommendations on the Management of Patients With Nonvariceal Upper Gastrointestinal Bleeding. Annals of Internal Medicine. 2010;152(2):101.

7. Huddy JR, Ni MZ, Markar SR, Hanna GB. Point-of-care testing in the diagnosis of gastrointestinal cancers: Current technology and future directions. World Journal of Gastroenterology. 2015;21(14):4111.

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