What is the initial workup for an adult patient with a history of gastrointestinal issues presenting with rectal bleeding?

Workup in Bleeding Per Rectum

Initial Assessment

Begin with immediate hemodynamic assessment including vital signs (pulse, blood pressure), followed by focused history, digital rectal examination, and laboratory evaluation to determine bleeding severity and guide management. 1

Hemodynamic Evaluation

• Check vital signs immediately to assess hemodynamic stability, including pulse rate, blood pressure, and signs of shock 1, 2
• Calculate shock index (heart rate/systolic BP); a shock index >1 indicates hemodynamic instability requiring urgent intervention 3
• Monitor for signs of volume depletion including tachycardia (pulse ≥100 bpm) and hypotension (systolic BP ≤100 mmHg) 2

Focused Medical History

• Obtain history of prior abdominal surgery (85% sensitivity for adhesive bowel obstruction if presenting with obstruction symptoms) 1
• Document medication use, particularly anticoagulants (warfarin, DOACs, heparin), antiplatelet agents (aspirin, P2Y12 inhibitors), and NSAIDs 3, 2
• Assess for liver disease or portal hypertension history, as anorectal varices occur in up to 89% of patients with portal pressure >10 mmHg 1
• Inquire about previous episodes of rectal bleeding, chronic constipation, unexplained weight loss, or recent trauma 1, 4
• Document last bowel movement and whether bowel is passing gas 1

Physical Examination

• Perform digital rectal examination (DRE) to rule out other causes of lower gastrointestinal bleeding and assess for masses, hemorrhoids, fissures, or blood 1, 2
• Examine for abdominal tenderness, distension, or peritoneal signs 1
• Assess for signs of chronic liver disease (jaundice, ascites, spider angiomata) if portal hypertension suspected 1
• In females of childbearing age, consider pregnancy testing 1

Laboratory Investigations

Essential Blood Tests

• Complete blood count (CBC) with hemoglobin and hematocrit to assess severity of bleeding 1, 2
• Coagulation studies including PT/INR, aPTT, and platelet count to evaluate coagulopathy 1, 3, 2
• Serum electrolytes, blood urea nitrogen (BUN), and creatinine to assess metabolic status and renal function 1, 2
• Inflammatory markers (C-reactive protein, procalcitonin, lactate) if bowel ischemia or sepsis suspected 1

Blood Product Preparation

• Blood type and cross-match should be ordered immediately in patients with signs of severe bleeding (hemodynamic instability, ongoing bleeding, or hemoglobin <7-8 g/dL) 1, 2

Risk Stratification

Use the Oakland score in hemodynamically stable patients with self-limited bleeding; a score ≤8 points allows safe discharge for outpatient investigation. 2

Risk stratification scores incorporate:

• Vital signs and hemodynamic parameters 1
• Presence of blood at rectal examination 1
• Laboratory values (hematocrit, creatinine, albumin) 1
• Comorbidities and anticoagulant/antiplatelet use 1

Endoscopic Evaluation

Timing and Approach

• Anoscopy or proctosigmoidoscopy should be performed as first-line diagnostic tool when feasible and well-tolerated 1, 4
• Flexible sigmoidoscopy or colonoscopy is recommended for all patients reporting rectal bleeding to adequately assess the source 4, 2
• Urgent colonoscopy within 24 hours is indicated for patients with high-risk features, evidence of ongoing bleeding, or hemodynamic instability 1, 2
• Outpatient colonoscopy can be arranged for stable patients with self-limited bleeding episodes and Oakland score ≤8 4, 2

Important Considerations

• Colonoscopy has very high diagnostic yield (84% abnormal findings in one study) and is recommended in the workup of bleeding per rectum 5
• The entire colon should be evaluated regardless of rectal examination findings, as 48% of patients have concomitant findings that change management 6
• Endoscopy should be performed by experienced endoscopists capable of therapeutic interventions 1

Imaging Investigations

When to Image

• CT angiography (CTA) should be performed immediately in hemodynamically unstable patients with suspected ongoing bleeding before endoscopic or radiological therapy to locate the bleeding source 3, 2
• Contrast-enhanced CT scan is indicated if endoscopy fails to detect bleeding site or when endoscopic ultrasound is unavailable 1
• Imaging (CT, MRI, or endoanal ultrasound) should only be performed if there is suspicion of concomitant anorectal diseases (abscess, inflammatory bowel disease, neoplasm) 1, 4

Special Populations

• MRI angiography is preferred in pregnant patients with failed ultrasound detection of bleeding site, if available and clinically appropriate 1

Differential Diagnosis Considerations

Common Causes

• Hemorrhoids are the most common benign cause, presenting as discrete radial bulging of anal cushions (not crossing dentate line) 1, 3
• Ulcerative colitis was the leading cause (46%) in one diagnostic series 5
• Colorectal carcinoma accounts for approximately 10% of cases presenting with rectal bleeding 5
• Diverticular disease is responsible for 6-10% of lower GI bleeding 5

Less Common but Important Causes

• Anorectal varices appear as discrete, compressible, serpiginous submucosal veins crossing the dentate line in patients with portal hypertension 1, 3
• Anal fissures from trauma (including mechanical trauma from anal intercourse or douching) 4
• Rectal prolapse presents as circumferential full-thickness protrusion through the anus 1
• Solitary rectal ulcer, polyps, arteriovenous malformations are less frequent findings 5

Critical Pitfalls to Avoid

• Do not rely on initial hemoglobin values alone, as they may appear falsely normal in the first 30-60 minutes after acute bleeding; serial measurements are essential 7
• Do not assume hemorrhoids are the sole cause without full colonic evaluation, as significant proximal pathology exists in many patients 6, 8
• Patient descriptions of bleeding are somewhat unreliable; physician-documented bleeding has higher diagnostic yield (22.5%) than patient-reported bleeding (5.9%) 8
• Do not delay appropriate treatment for imaging in unstable patients; stabilization takes priority 1
• Sixteen of 18 lesions in one series were in the left colon, emphasizing the importance of complete examination 8