GI Bleeding — Upper vs Lower

A patient presents with dark, tarry stool and another with bright red blood per rectum — both are GI bleeds, but the location changes everything about your assessment priorities and expected interventions.

GI bleeding is classified by its origin relative to the ligament of Treitz. Upper GI bleeds (above this landmark) most commonly present with hematemesis (bright red or coffee-ground emesis) and melena (black, tarry, foul-smelling stool). Lower GI bleeds (below) typically present with hematochezia (bright red or maroon blood per rectum). However, a brisk upper GI bleed can produce hematochezia — so bright red rectal bleeding with hemodynamic instability should raise suspicion for an upper source. Nursing priorities center on hemodynamic monitoring: tachycardia is often the earliest sign of significant blood loss, appearing before hypotension. Assess for orthostatic vital sign changes (drop of ≥20 mmHg systolic or ≥10 mmHg diastolic, or pulse rise ≥20 bpm upon standing). Establish two large-bore IV lines (16-18 gauge) for volume resuscitation. Monitor hemoglobin and hematocrit, but recognize these values lag behind acute blood loss by 6-24 hours. Track BUN — an elevated BUN-to-creatinine ratio (>20:1) suggests an upper GI source because digested blood increases nitrogen absorption. Stool testing (guaiac/occult blood) confirms bleeding when it isn't visually obvious. Maintain NPO status, anticipate type and crossmatch, and prepare for possible endoscopy.

Key Distinctions

Don't confuse melena with hematochezia — melena is black and tarry (upper source, digested blood), hematochezia is bright red (usually lower, but can indicate massive upper bleed). Students assume a normal H&H rules out active bleeding — in acute hemorrhage, H&H doesn't drop until fluid shifts compensate, often 6-24 hours later. An elevated BUN with normal creatinine points to upper GI bleeding, not renal failure.

Clinical Pearl

Tachycardia before hypotension: the heart speeds up to compensate before pressure drops. If your GI bleed patient's heart rate is climbing, don't wait for the BP to fall.