Can hemorrhoids (hemorrhoidal disease) cause a positive Hemoccult (fecal occult blood test)?

Hemorrhoids and Positive Hemoccult Tests

Hemorrhoids alone do not cause a positive result with a stool guaiac test (Hemoccult), so fecal occult blood should not be attributed to hemorrhoids until the colon is adequately evaluated. 1

Relationship Between Hemorrhoids and Fecal Occult Blood Tests

• Hemorrhoidal bleeding typically presents as bright red blood that may drip or squirt into the toilet bowl, rather than occult (hidden) blood that would be detected on a Hemoccult test 1
• When a positive fecal occult blood test is found in a patient with hemorrhoids, this finding should not be attributed to the hemorrhoids without further investigation 1
• Complete colonic evaluation by colonoscopy or air-contrast barium enema is indicated when a patient has a positive stool guaiac test, even if hemorrhoids are present 1

Diagnostic Approach for Positive Hemoccult with Hemorrhoids

Initial Assessment

• Collect a focused medical history and perform a complete physical examination, including digital rectal examination, to rule out other causes of lower gastrointestinal bleeding 1
• Check vital signs, determine hemoglobin and hematocrit, and assess coagulation to evaluate the severity of any bleeding 1

Further Investigation

• Anoscopy and flexible sigmoidoscopy represent the minimum evaluation for bright-red rectal bleeding 1
• Complete colonic evaluation is mandatory when:
  • The bleeding is atypical for hemorrhoids
  • No source is evident on anorectal examination
  • The patient has significant risk factors for colonic neoplasia
  • A positive Hemoccult test is present 1

Clinical Significance of Positive Hemoccult Tests

• In one study of patients with positive Hemoccult tests on rectal examination, neoplastic lesions were found in 28% of patients (including 13 adenocarcinomas and 38 adenomatous polyps) 2
• Even in patients taking anti-inflammatory drugs (which are often blamed for positive Hemoccult tests), underlying GI tract lesions were found in most cases with positive tests 3
• In a study of FOBT-positive patients, colorectal diseases were detected in 57.5% of cases, including colorectal cancer (13.7%), colonic polyps (15%), and inflammatory bowel disease (3.75%) 4

Common Pitfalls to Avoid

• Do not attribute a positive Hemoccult test to hemorrhoids without further investigation 1
• Remember that anemia due to hemorrhoidal disease is rare (0.5 patients/100,000 population) 1
• Be aware that certain substances can cause false-positive results on Hemoccult tests:
  • Iron preparations can cause false-positive results (50-65% with ferrous compounds) 5
  • Small amounts of upper GI tract bleeding can be detected by guaiac-based tests 6

Conclusion

When a patient with hemorrhoids has a positive Hemoccult test, a thorough evaluation of the colon is necessary to rule out other potential sources of bleeding. The presence of hemorrhoids should not deter clinicians from performing appropriate diagnostic procedures to identify potentially serious conditions such as colorectal cancer.