What further evaluation or labs are needed for a patient with a history of hematochezia (passage of blood per rectum) who has not had recurrence since emergency room treatment?

Follow-up Management After Resolved Hematochezia

You need to order a complete blood count (CBC) to assess for anemia, and the patient requires outpatient colonoscopy for definitive diagnosis, as approximately 75% of lower GI bleeding episodes stop spontaneously but the underlying cause must still be identified. 1

Essential Laboratory Testing

• Order a CBC with hemoglobin and hematocrit to evaluate for anemia from either the acute bleeding episode or chronic occult blood loss 1
• Check coagulation parameters (PT/INR, PTT) if the patient is on anticoagulation or antiplatelet therapy, as these are risk factors for GI bleeding 2
• Consider a BUN/creatinine ratio, as an elevated ratio may suggest an upper GI source that was missed in the ER 2, 3

Colonoscopy Referral is Mandatory

• Schedule outpatient colonoscopy as the definitive diagnostic test, even though bleeding has stopped, because the source must be identified 1, 3
• The diagnostic yield of colonoscopy for lower GI bleeding ranges from 72-86%, making it the gold standard investigation 3
• Colonoscopy provides both diagnostic capability and therapeutic intervention if a bleeding source is identified 1

Critical Consideration: Exclude Upper GI Source

• Up to 15% of patients presenting with hematochezia actually have an upper GI bleeding source, particularly those with hemodynamic instability, history of peptic ulcer disease, portal hypertension, or use of antiplatelet drugs 2, 3
• If the patient had significant hemodynamic compromise in the ER or has risk factors for upper GI bleeding, consider adding upper endoscopy to the colonoscopy referral 2, 3
• Review what evaluation was done in the ER—if no upper endoscopy was performed and the patient had brisk bleeding or instability, upper endoscopy should be included 3

Timing and Preparation

• While urgent colonoscopy within 24 hours is recommended for ongoing bleeding or high-risk features, your patient with resolved bleeding can undergo elective outpatient colonoscopy with proper bowel preparation 1
• Ensure thorough bowel preparation instructions are provided, as poor preparation leads to incomplete evaluation and missed diagnoses 1

Common Pitfall to Avoid

• Do not assume the bleeding was from hemorrhoids without colonoscopic confirmation, especially if the patient is over 50 years or has risk factors for colorectal cancer 2, 4
• The estimated risk of colorectal cancer in patients with rectal bleeding ranges from 2.4-11%, making complete colonic evaluation essential 2
• Even if an anorectal source like hemorrhoids is suspected, patients may have a more proximal source of bleeding that requires full colonoscopy to exclude 2

Documentation for Referral

• Provide the gastroenterologist with: hemodynamic status in the ER, estimated blood loss, transfusion requirements (if any), current hemoglobin level, medication list (especially anticoagulants/antiplatelets), and any imaging or procedures done in the ER 1
• Note that approximately 75% of lower GI bleeding episodes stop spontaneously, particularly in patients requiring <4 units of blood transfusion over 24 hours, but this does not eliminate the need for diagnostic evaluation 1