What is the evaluation and management of hematochezia (passage of fresh blood per the rectum)?

Evaluation and Management of Hematochezia

Immediately assess hemodynamic stability with vital signs, establish large-bore IV access, and perform urgent colonoscopy within 24 hours after bowel preparation as the first-line diagnostic and therapeutic approach. 1

Initial Resuscitation and Stabilization

Hemodynamic assessment is the absolute first priority before any diagnostic workup:

• Check vital signs, capillary refill, and signs of shock immediately upon presentation 2, 1
• Establish two large-bore IV lines for fluid resuscitation and potential blood product administration in severe bleeding 1
• Maintain hemoglobin >7 g/dL and mean arterial pressure >65 mmHg while avoiding fluid overload 1
• Insert urinary catheter to monitor hourly urine output (target >30 mL/hr) in severe cases 1

Critical laboratory tests to order immediately:

• Complete blood count (CBC) to assess hemoglobin and hematocrit 2, 1
• Coagulation parameters (PT/INR, PTT) 2, 1
• Blood urea nitrogen (BUN) and creatinine 2
• Serum electrolytes 2
• Blood type and cross-match for patients with signs of severe bleeding 2
• Pregnancy test in women of childbearing age if applicable 2

Correct coagulopathy before any invasive procedures 1. Consider temporarily discontinuing antiplatelet agents during acute bleeding episodes 1.

Focused History and Physical Examination

Key historical elements to elicit:

• Characteristics of bleeding: bright red blood dripping/squirting suggests lower GI source, while darker blood mixed with stool suggests more proximal bleeding 2
• Presence of portal hypertension or chronic liver disease (raises suspicion for anorectal varices) 2
• Recent NSAID use, anticoagulation, or antiplatelet therapy 2
• Associated symptoms: acute anal pain (hemorrhoidal crisis, fissure, abscess), postdefecatory pain (anal fissure), or painless bleeding (diverticulosis, angiodysplasia) 2
• Prior episodes of hematochezia 2
• Risk factors for colorectal neoplasia 2

Essential physical examination components:

• Digital rectal examination to assess for masses, fissures, or blood 2
• External anal inspection for thrombosed hemorrhoids, skin tags, abscesses, or fistulas 2
• Anoscopy with adequate lighting to evaluate internal hemorrhoids and rectal mucosa 2
• Nasogastric lavage if there is medium to low suspicion of upper GI source, as 10-15% of severe hematochezia originates from upper GI tract 1

Diagnostic Algorithm

Step 1: Upper GI Exclusion

Perform upper endoscopy first in hemodynamically unstable patients or those with severe bleeding to exclude an upper GI source, as up to 15% of patients presenting with hematochezia have upper GI bleeding 1, 3. Nasogastric lavage is warranted when suspicion for upper GI source is medium to low 1.

Step 2: Urgent Colonoscopy (First-Line)

Urgent colonoscopy within 24 hours after hemodynamic stabilization is the gold standard diagnostic and therapeutic approach 1, 3:

• Ensure thorough bowel preparation with oral purge to clear blood, clots, and stool for optimal visualization 1, 4
• Sulfate-based purge appears safer than saline purge 4
• Colonoscopy identifies the bleeding source in approximately 78% of cases 5
• Complete examination with terminal ileum intubation is recommended 6
• Multiple endoscopic hemostatic techniques available: injection therapy, thermal coagulation, mechanical clips 1

Common causes identified on colonoscopy:

• Diverticular disease (most common cause, 30% of cases, with right-sided diverticulosis accounting for 44% of diverticular bleeding in Asian populations) 5
• Angiodysplasia (most common in cecum and proximal ascending colon) 1
• Polyps or colorectal cancer 5
• Inflammatory bowel disease or colitis 1
• Hemorrhoids (though physicians should not assume hemorrhoids without excluding other pathology) 2

Step 3: If Initial Colonoscopy is Inconclusive

Follow this sequential approach when colonoscopy fails to identify the source:

• Repeat colonoscopy with meticulous bowel preparation if initial examination suggests bleeding around the ileocecal valve 1, 3
• Radionuclide imaging with 99Tcm-labeled red blood cells if repeat colonoscopy is negative (detects bleeding rates of 0.1-0.5 mL/min) 1, 3
• CT angiography for hemodynamically unstable patients or those with suspected active bleeding to rapidly localize the source 1, 3
• Conventional angiography only after positive scintigraphy or in patients with hemodynamic instability and severe unremitting bleeding (requires bleeding rate ≥1 mL/min for detection) 1, 3

Therapeutic Interventions

Endoscopic hemostasis is the preferred first-line treatment for accessible bleeding sources identified during colonoscopy 1:

• Injection therapy, thermal coagulation, or mechanical clips for focal lesions 1
• For anorectal varices with mild bleeding: optimize portal hypertension medications with supportive care; avoid standard hemorrhoidal treatments 2, 1
• For radiation proctitis: consider formalin application, sucralfate enemas, or argon plasma coagulation 1

Surgical intervention is indicated in 16-24% of cases when endoscopic therapy fails or is not feasible 5, 4.

Critical Pitfalls to Avoid

• Never delay resuscitation to perform diagnostic procedures—stabilization always takes priority 1
• Do not assume hemorrhoids without excluding other pathology, especially in children where internal hemorrhoids are exceedingly rare 2, 7
• Avoid inadequate bowel preparation which leads to poor visualization and missed diagnoses 1, 3
• Do not over-transfuse, particularly in patients with portal hypertension, as this may increase portal pressure and worsen variceal bleeding 1
• Never attribute fecal occult blood to hemorrhoids until the colon is adequately evaluated 2
• Do not proceed directly to surgery without attempting to localize bleeding through endoscopic or radiological modalities first 1

Natural History and Prognosis

Approximately 75% of acute lower GI bleeding episodes from diverticulosis stop spontaneously, especially in patients requiring <4 units of blood transfusion over 24 hours 1, 3. Overall mortality related to severe hematochezia is approximately 5% 5.