What are the potential causes and appropriate management for a patient presenting with hematochezia (blood in stool)?

Blood in Stool: Causes and Management

Immediate Assessment Priority

All patients presenting with blood in stool require hemodynamic assessment and risk stratification using the Oakland score, with scores >8 mandating hospital admission and colonoscopy within 24 hours. 1

Initial Hemodynamic Evaluation

• Check vital signs including shock index, perform digital rectal examination, and obtain complete blood count, coagulation studies, and basic metabolic panel 1
• Resuscitate with intravenous fluids to normalize blood pressure and heart rate 2, 1
• Transfuse packed red blood cells to maintain hemoglobin >7 g/dL (or >9 g/dL in patients with cardiovascular disease or massive bleeding) 2, 1
• Correct coagulopathy if INR >1.5 with fresh frozen plasma and vitamin K 2, 1

Oakland Score Risk Stratification

The Oakland score determines admission need and urgency of evaluation 1:

• Score >8 (major bleeding): Hospital admission with colonoscopy within 24 hours 1
• Score ≤8 (minor bleeding): Discharge for urgent outpatient colonoscopy within 2 weeks 1

Points assigned: age ≥70 years (2 points), male gender (1 point), previous lower GI bleeding (1 point), blood on digital rectal examination (1 point), plus heart rate, blood pressure, and hemoglobin scoring 1

Differential Diagnosis by Presentation

Bright Red Blood (Hematochezia)

Diverticulosis is the most common cause of hematochezia in adults, accounting for 30-41% of cases, typically presenting as painless, large-volume bright red blood. 3

Common causes include:

• Diverticulosis (30-41%): Painless, large-volume bleeding 3
• Angiodysplasia (20-40%): Particularly in patients >65 years, associated with chronic kidney disease and aortic stenosis 3
• Hemorrhoids (14-24%): Bright red blood coating stool or on toilet paper, may have prolapse or thrombosis 3
• Colorectal cancer/polyps (11-22%): Risk increases with age and family history 3
• Inflammatory bowel disease: Diffuse mucosal ulceration (UC) or focal vessel erosion (CD) 2, 3
• Ischemic colitis (6-21%): Typically in elderly patients with vascular disease 3

Dark Red Blood Mixed with Stool

Dark red blood mixed with stool indicates a proximal colonic source and mandates complete colonoscopy rather than assuming hemorrhoidal bleeding. 1

• This presentation suggests more proximal colonic pathology requiring full colonic evaluation 1
• Hemorrhoids cause bright red blood that drips or squirts into the toilet bowl, not dark blood mixed with stool 1

Critical Upper GI Sources

Up to 15% of patients with severe hematochezia have an upper GI bleeding source, particularly those with hemodynamic instability. 3, 4

• Duodenal ulcer is the most common cause (44%) of upper GI bleeding presenting as hematochezia 4
• Patients with hematochezia from upper GI sources have higher transfusion requirements (5.4 vs 4.0 units), need for surgery (11.7% vs 5.7%), and mortality (13.6% vs 7.5%) compared to those with melena 4
• Melena on examination (LR 5.1-5.9), nasogastric lavage with blood or coffee grounds (LR 9.6), and BUN:creatinine ratio >30 (LR 7.5) increase likelihood of upper GI source 5

Diagnostic Algorithm

Step 1: Rule Out Upper GI Source

In hemodynamically unstable patients or those with severe bleeding, perform upper endoscopy first to exclude upper GI bleeding before proceeding to colonoscopy. 2, 1

• Upper endoscopy should be the initial diagnostic procedure for stable patients with acute GI bleeding 2
• Blood clots in stool decrease likelihood of upper GI bleeding (LR 0.05) 5

Step 2: Anorectal Examination

• Perform digital rectal examination to confirm blood and exclude anorectal pathology 2, 6
• Direct visualization with anoscopy is essential for diagnosis of hemorrhoids and other anorectal pathology 6
• Approximately 40% of rectal carcinomas are palpable on digital rectal examination 2

Step 3: Colonoscopy

Colonoscopy after adequate bowel preparation is the preferred initial diagnostic test for lower GI bleeding in stable patients. 1, 7

• Flexible sigmoidoscopy or colonoscopy is recommended for nearly all patients with rectal bleeding, even when hemorrhoids are identified 6
• Complete colonic evaluation is mandatory when bleeding is atypical for hemorrhoids, no source is evident on anorectal examination, or patient has risk factors for colorectal neoplasia 6, 1
• Urgent colonoscopy after oral purge in the intensive care unit is effective and safe for patients with severe ongoing hematochezia, with 64% requiring intervention (39% therapeutic endoscopy, 24% surgery) 7

Step 4: Advanced Imaging if Needed

• CT angiography should be performed in patients with ongoing bleeding who are hemodynamically stable after resuscitation 2
• Radionuclide scanning followed by angiography may be considered if colonoscopy is non-diagnostic and bleeding continues 7

Critical Pitfalls to Avoid

Never assume hemorrhoids are the cause without proper evaluation, as symptoms attributed to hemorrhoids frequently represent other pathology, including colorectal cancer. 3, 6

• Colorectal cancer accounts for 6% of all lower GI bleeding presentations 1
• Anemia due to hemorrhoidal disease is rare and should prompt search for alternative diagnoses 6
• Portal hypertension causes anorectal varices (compressible, serpiginous submucosal veins crossing the dentate line), not hemorrhoids, requiring different management 3
• Failing to recognize that 6% of patients presenting with lower GI bleeding have underlying bowel cancer makes timely investigation essential in patients over 50 with unexplained rectal bleeding 1

Surgical Intervention Indications

Immediate surgery is recommended in unstable patients with hemorrhagic shock non-responsive to resuscitation, and in patients with acute severe ulcerative colitis and refractory hemorrhage. 2

• Surgical treatment is indicated for life-threatening bleeding with persistent hemodynamic instability 2
• Subtotal colectomy with ileostomy is the surgical treatment of choice for acute severe ulcerative colitis with refractory hemorrhage 2
• Significant recurrent gastrointestinal bleeding may be an indication for urgent surgery 2

Age-Specific Considerations

• Patients >65 years are more likely to have diverticulosis and angiodysplasia 3
• Younger patients <50 years are more likely to have hemorrhoids, anal fissures, and inflammatory bowel disease, though colorectal cancer risk cannot be excluded based on age alone 3
• Elderly patients are at greater risk of endoscopic complications (0.24-4.9% vs 0.03-0.13% in younger patients), with cardiopulmonary events accounting for >50% of complications 2