Lower GI Bleed: Diverticular vs Hemorrhoidal — Resuscitation, CT-Angio & Colonoscopy Timing

Brisk hematochezia can be dramatic. The keys are resuscitation, smart imaging, and the right scope at the right time. This pathway frames common sources (diverticular, angiodysplasia, hemorrhoids, ischemic colitis) and when to use CT-angiography, colonoscopy, or embolization.

Step 1 — Stabilize First

• Two large-bore IVs, monitor, serial vitals, orthostatics when appropriate.
• Labs: CBC, CMP, type & cross, PT/INR, PTT; consider venous lactate.
• Transfusion: restrictive strategy similar to UGIB (RBC when Hgb ≲7 g/dL; ≲8 g/dL if ischemia/ACS or persistent shock). Correct platelets/coagulopathy for active bleeding or procedures.
• Reverse anticoagulation when indicated (4-factor PCC + vitamin K for warfarin; DOAC reversal per local protocol). Balance thrombotic risk with cardiology/hem-onc as needed.
• If hemodynamically unstable with ongoing hematochezia, treat as potential upper source too—clinical judgment for early upper endoscopy if suspicion (history of PUD, melena/hematemesis, NG findings).

Step 2 — Initial Differentials & Clues

• Diverticular bleeding: sudden, painless, often large-volume bright red or maroon blood; may stop spontaneously but can recur.
• Angiodysplasia: intermittent, occult/iron-deficiency or overt bleeding in older adults; aortic stenosis and CKD associations.
• Hemorrhoids/anal fissure: scant bright red blood on tissue or toilet, pain/itch with fissure; normal vitals/hemoglobin.
• Ischemic colitis: crampy LLQ pain, urgency, low-volume hematochezia after hypotension/low-flow states; tenderness on exam.
• Inflammatory/infectious colitis, neoplasia, radiation proctitis as context suggests.

Step 3 — Imaging vs Endoscopy: Who, What, When

• CT-angiography (CTA) is first-line when active moderate–severe bleeding is suspected (ongoing hematochezia, hemodynamic instability, transfusion requirement). It can localize bleeding (as low as ~0.3–0.5 mL/min) and guide IR embolization.
• Urgent colonoscopy requires adequate bowel prep (e.g., 4–6 L PEG split/rapid prep). Best once patient is stabilized; often within 24 hours for most hospitalized cases.
• IR embolization (after positive CTA) is effective for focal arterial bleeding unamenable to or preceding endoscopy.
• Tagged RBC scan is less specific but may help in intermittent/slow bleeds when CTA is negative/unavailable.

Step 4 — Colonoscopy Technique & Therapy

• Identify stigmata: active bleed, visible vessel, adherent clot (diverticulum), or vascular ectasias.
• Therapies include injection (epi), mechanical clips, thermal coagulation, or APC for angiodysplasia.
• Hemorrhoids: office procedures outpatient (rubber band ligation) unless severe anemia or refractory bleeding.

Ischemic Colitis (brief pathway)

• Supportive care: IV fluids, bowel rest, analgesia; treat precipitant (hypotension, arrhythmia).
• Broad-spectrum antibiotics in moderate–severe disease per institutional protocol.
• CT with IV contrast shows segmental colitis (often splenic flexure/left colon). Colonoscopy (limited, gentle) may confirm.
• Surgery for peritonitis, transmural necrosis, or fulminant course.

Antithrombotics: Pause, Reverse, Restart

• Aspirin for secondary prevention: if held, typically restart early (within 3–5 days) after hemostasis, individualized by CV risk.
• Dual antiplatelet/anticoagulants: multidisciplinary plan (GI + cardiology/hematology); resume within days once bleeding controlled in high thrombotic-risk patients.

Disposition & Risk Tools

• Oakland score can help identify low-risk patients suitable for outpatient management if vitals stable, Hgb adequate, and no red flags.
• Admit for ongoing bleeding, need for transfusion, hemodynamic changes, significant comorbidity, or inadequate social support.

Pearls & Pitfalls

• Don’t delay CTA in active, unstable hematochezia—localization enables definitive IR therapy.
• Colonoscopy without prep is low-yield; prioritize rapid PEG prep once stabilized.
• Hemorrhoids are common but rarely cause major anemia—look proximally if labs or story don’t fit.
• Rebleeding after diverticular hemostasis can occur—set expectations and follow-up.

Patient FAQs

“Why do I need that big bowel prep?” A clear colon lets the endoscopist find and treat the exact bleeding site safely.

“If the CT shows the spot, do I still need a scope?” Often we go straight to IR to embolize during active bleeding; colonoscopy follows for diagnosis and prevention planning.

References & Notes

Practical LGIB pathway: stabilize with restrictive transfusion, reverse anticoagulation judiciously, use CTA for active bleeding, perform colonoscopy after adequate prep (usually within 24 h), and employ IR embolization when indicated. Local protocols vary—follow institutional guidance. Educational only.