What is the appropriate evaluation and management of a patient presenting with hematochezia?

Evaluation of Hematochezia

Immediate Hemodynamic Assessment

Begin with immediate assessment of vital signs, complete blood count with hemoglobin/hematocrit, and coagulation parameters to determine bleeding severity and guide resuscitation priorities. 1

• Establish two large-bore IV lines for fluid resuscitation and potential blood product administration in patients with severe bleeding 1
• Maintain hemoglobin >7 g/dL and mean arterial pressure >65 mmHg while avoiding fluid overload 1
• Perform blood typing and cross-matching for patients showing signs of severe bleeding 2
• Include serum electrolytes, BUN, and creatinine in initial laboratory assessment 2
• Insert urinary catheter to monitor hourly urine output (target >30 mL/hr) in severe cases 1
• Consider pregnancy testing in women of childbearing age 2

Critical History and Physical Examination

Obtain focused medical history emphasizing timing of bleeding, associated symptoms, medication use (especially anticoagulants/antiplatelets), and history of liver disease or portal hypertension. 2

• Perform digital rectal examination to assess for anorectal pathology and confirm presence of blood 2
• Document presence of hemodynamic instability, as this increases likelihood of upper GI source 1, 3
• Identify risk factors for upper GI bleeding including peptic ulcer disease, portal hypertension, and antiplatelet drug use 4
• Assess for comorbidities and use risk stratification scores incorporating vital signs, laboratory values, and medication history 2

Exclude Upper GI Source First

Perform upper endoscopy before colonoscopy in patients with hemodynamic instability or risk factors for upper GI bleeding, as 10-15% of patients with severe hematochezia have an upper GI source. 1, 4, 3

• Upper endoscopy should be performed within 6 hours in patients with serious hematochezia and high-risk features 3
• Consider nasogastric lavage if there is medium to low suspicion of upper GI source 1
• An elevated BUN/creatinine ratio may suggest an upper GI source 4

Colonoscopy as Primary Diagnostic Modality

Perform urgent colonoscopy within 24 hours after hemodynamic stabilization as the first-line diagnostic approach, with diagnostic yield of 72-86%. 1, 5, 6

• Ensure thorough bowel preparation with oral purge to clear blood, clots, and stool for optimal visualization 6, 7
• Sulfate-based purge appears safer than saline purge, though fluid retention can occur in 4% of patients 7
• Colonoscopy provides both diagnostic capability and immediate therapeutic intervention 4, 6
• In one study, 23% of patients had definite signs of diverticular hemorrhage (active bleeding, visible vessels, or adherent clots) on urgent colonoscopy 6

Timing Considerations

The evidence on urgent versus elective colonoscopy timing is nuanced. While guidelines recommend urgent colonoscopy within 24 hours 1, one randomized trial found no significant difference in outcomes between urgent (≤12 hours) versus elective (36-60 hours) colonoscopy in patients without upper GI source 3. However, urgent colonoscopy after purge has demonstrated effectiveness in identifying bleeding sources in 78% of cases 5 and allows for immediate therapeutic intervention 6, 7.

Alternative Imaging When Colonoscopy Inconclusive

If initial colonoscopy fails to identify the bleeding source, proceed with radionuclide imaging (technetium-99m labeled red blood cells) which can detect bleeding rates as low as 0.1-0.5 mL/min. 1, 8

• CT angiography may be performed first in hemodynamically unstable patients to rapidly localize bleeding 1, 8
• Angiography requires bleeding rate ≥1 mL/min for detection and should only be performed after positive scintigraphy or in patients with severe unremitting bleeding 1, 8
• In one series, emergency visceral angiography had only 14% diagnostic yield with 9% complication rate, compared to much higher yield with colonoscopy 7
• Repeat colonoscopy with thorough bowel preparation should be considered if initial examination suggests bleeding around ileocecal valve 1, 8

Therapeutic Interventions

Endoscopic hemostasis is the preferred first-line treatment for accessible bleeding sources, using injection therapy (epinephrine), thermal coagulation (bipolar), or mechanical methods (clips). 1, 6, 7

• In patients with definite diverticular hemorrhage treated endoscopically, none had recurrent bleeding or required surgery in one study 6
• Approximately 75% of diverticular bleeding episodes stop spontaneously, particularly in patients requiring <4 units transfusion over 24 hours 1, 8
• For anorectal varices with mild bleeding, optimize portal hypertension medications with supportive care 1

Special Diagnostic Considerations

Anorectal Varices

• Perform endoscopic ultrasound with color Doppler as second-line tool for deep rectal varices, as EUS detects varices in 85% versus 45% with endoscopy alone 2
• Consider contrast-enhanced CT if EUS unavailable or fails to detect bleeding 2
• Use MRI angiography in pregnant patients if ultrasound fails and clinical scenario permits 2

Hemorrhoidal Bleeding

• Imaging (CT, MRI, or endoanal ultrasound) should only be performed if suspicion exists for concomitant anorectal disease such as abscess, inflammatory bowel disease, or neoplasm 2
• Medical history and physical examination are key factors driving diagnostic workup, as imaging has limited role in uncomplicated hemorrhoidal bleeding 2

Common Causes by Frequency

Diverticular disease is the most common cause of severe hematochezia (30% of cases), with right-sided diverticular bleeding accounting for 44% of diverticular hemorrhage. 1, 5

• Angiodysplasia occurs most commonly in cecum and proximal ascending colon 1
• Other causes include polyps/cancer (11%), focal ulcers (9%), inflammatory bowel disease, and radiation proctitis 1, 5

Critical Pitfalls to Avoid

• Never delay resuscitation to perform diagnostic procedures—stabilization always takes priority 1
• Inadequate bowel preparation leads to poor visualization and missed diagnoses—ensure thorough purge before colonoscopy 1, 6, 7
• Over-transfusion may increase portal pressure and worsen bleeding in patients with portal hypertension 1
• Premature surgery without attempting radiological/endoscopic localization reduces diagnostic accuracy 1
• Assuming hemorrhoids are the source without complete colonic evaluation—2.4-11% of patients with rectal bleeding have colorectal cancer 4
• Failing to consider upper GI source in hemodynamically unstable patients—15% have upper GI bleeding despite hematochezia presentation 1, 4, 3