Acute Lower Gastrointestinal Bleeding

Assessment, risk stratification, colonoscopy timing, and management — ACG 2023 Guidelines.

Initial Assessment

Stabilization and risk stratification

Acute Lower GI Bleed: Initial Assessment

LGIB presents as hematochezia. Severity ranges from self-limited to life-threatening. Rapid assessment and resuscitation precede definitive diagnosis.

Hemodynamic Instability — Immediate Action

2 large-bore IVs or central access

Blood type and crossmatch

Crystalloid resuscitation → packed RBCs if Hgb <7 (or <8 if cardiac disease)

Consider platelet transfusion if <50K + active bleed

Reverse anticoagulation if clinically significant (idarucizumab for dabigatran, andexanet alfa for FXa inhibitors)

ICU admission if hemodynamically unstable

Risk Score	Factors	Clinical Use
Oakland Score	Age, sex, Hgb, rectal exam, BUN, hemodynamics, comorbidities	Low risk (≤8) → safe for outpatient management
NOBLADS Score	NSAIDs, no diarrhea, no rectal bleeding, antiplatelet, no laxative, albumin, diverticulosis, syncope	Predicts severe LGIB requiring intervention
GBS (Glasgow-Blatchford)	Originally for UGIB; adapted for LGIB risk stratification	Useful when UGI source not yet excluded

Exclude UGIB First

Up to 15% of apparent LGIB (hematochezia) originates from an upper GI source. Nasogastric lavage is NOT required; instead, assess for signs of UGIB (coffee ground, melena, hematemesis history, BUN:Cr ratio >25). EGD should precede colonoscopy if UGIB is suspected.

Sengupta N et al. ACG Clinical Guideline: Management of Patients With Acute Lower Gastrointestinal Bleeding. Am J Gastroenterol. 2023.