Lower GI Bleeding Management (ACG 2023)

Algorithm Steps

1. ▶

   Start

   START: Acute Lower GI Bleeding

   Hematochezia or maroon stool

   1. ●

      Action

      Initial Assessment & Resuscitation

      Stabilize patient

      • 2 large-bore IVs
      • Type and screen/crossmatch
      • CBC, BMP, coags, LFTs
      • Rectal exam to confirm hematochezia
      • Consider NG tube/EGD if brisk bleeding (r/o upper source)
      1. ◆

         Decision

         Hemodynamically Stable?

         Assess stability

         • UNSTABLE: SBP <90, HR >100, signs of shock
         • STABLE: Normal vitals, no active bleeding
         1. ⚠

            Warning

            Hemodynamically Unstable

            Aggressive resuscitation

            • Crystalloid resuscitation
            • Blood transfusion (target Hgb ≥7, or ≥8 if CAD)
            • Consider massive transfusion if ongoing
            • Correct coagulopathy
            • Rule out upper GI source with NG aspirate or EGD
            1. ◆

               Decision

               Colonoscopy Timing

               Based on risk and stability

               • URGENT (<24h): Hemodynamic instability, high-risk features
               • ELECTIVE (24-72h): Stable, low-risk patients
               1. ●

                  Action

                  Bowel Preparation

                  Prep before colonoscopy

                  • Polyethylene glycol-based prep (4-6L over 3-4 hrs)
                  • NG tube if unable to tolerate oral
                  • Adequate prep improves diagnostic yield
                  1. ●

                     Action

                     Colonoscopy

                     Diagnostic and therapeutic

                     • Identify bleeding source
                     • Common sources: Diverticulosis, angiodysplasia, hemorrhoids, neoplasm, colitis
                     • Endoscopic therapy if active bleeding or stigmata
                     1. ◆

                        Decision

                        Bleeding Source Identified?

                        Colonoscopy findings

                        1. ●

                           Action

                           Endoscopic Therapy

                           If active bleeding or stigmata

                           • Clips, thermal coagulation, or injection
                           • Combination therapy for high-risk lesions
                           • Tattoo lesion for localization if surgery needed
                           1. ◆

                              Decision

                              Rebleeding?

                              Monitor for recurrence

                              1. ⚠

                                 Warning

                                 Angiography or Surgery

                                 For refractory bleeding

                                 • CTA to localize if bleeding rate >0.5 mL/min
                                 • Angioembolization if source identified
                                 • Surgery if angiography fails or unavailable
                              2. ✓

                                 Outcome

                                 Discharge

                                 Stable, no rebleeding

                                 • Address underlying cause
                                 • Review anticoagulation/antiplatelet
                                 • GI follow-up
                                 • Return precautions
                        2. ●

                           Action

                           No Source Identified

                           Further workup

                           • If ongoing bleeding: CT angiography or tagged RBC scan
                           • Capsule endoscopy for occult/obscure bleeding
                           • Consider upper endoscopy if not done
         2. ●

            Action

            Risk Stratification

            Identify high-risk features

            • Oakland Score recommended
            • HIGH RISK: Hemodynamic instability, ongoing bleeding, Hgb <7, comorbidities, anticoagulation
            • LOW RISK: Oakland ≤8, no high-risk features
            1. ●

               Action

               Low Risk (Oakland ≤8)

               May consider outpatient management

               • Outpatient colonoscopy within 7 days
               • Discharge with clear instructions
               • Return if recurrent bleeding