ASCRS Ch40 - Lower GI Hemorrhage

Chapter 40, "Lower GI Hemorrhage," ASCRS Textbook of Colon and Rectal Surgery, 4th edition. Authors: Mehraneh D. Jafari and Joshua I.S. Bleier. Book pp. 699–713 (title page through References).

Textbook reference chapter (not primary literature), opening Part IV/benign-and-miscellaneous material (see the Ch35/Ch37 Part-boundary discrepancy noted on those pages — this chapter's own numbering doesn't resolve it). A comprehensive treatment of lower gastrointestinal bleeding (LGIB) — epidemiology/etiology, presentation, risk stratification, resuscitation/anticoagulation management, endoscopic and radiologic localization/treatment, recurrent LGIB, small bowel/obscure GI bleeding workup, and surgery. Genuinely new topic for the wiki — no prior page addressed LGIB as a distinct entity. Backs a new dedicated page, Lower Gastrointestinal Hemorrhage.

Structure

• Epidemiology and etiology: diverticulosis (30–65% of LGIB) and anorectal disease (5–20%) as the leading causes; Table 40.1 full etiology breakdown by category (anatomic, vascular, inflammatory, neoplastic, small bowel).
• Presentation and evaluation: hematochezia vs. melena, history/physical exam focus, medication history (anticoagulants/antiplatelets), initial assessment (vital signs, digital rectal exam, anoscopy, NGT lavage).
• Risk stratification: shock index; risk stratification models (less developed than for upper GI bleeds); named risk scores — Oakland score (Table 40.2, the only LGIB-specific externally validated score), BLEED, NOBLADS, Sengupta, Strate (Table 40.3); an artificial neural network model (Das et al.).
• Management: resuscitation targets (transfusion thresholds extrapolated from upper GI bleed literature), anticoagulation reversal (INR/DOAC management), platelet transfusion thresholds.
• Endoscopic evaluation and intervention: colonoscopy timing/diagnostic yield, technique (water- jet irrigation, terminal ileum intubation), high-risk stigmata, hemostatic modalities (injection, thermal coagulation, clips, banding) by etiology — diverticular bleeding, angioectasia (incl. Heyde syndrome), post-polypectomy bleeding.
• Radiologic evaluation: CT angiography (technique, sensitivity/specificity, shock-index-guided selection), catheter-based angiography (localization + treatment, embolization technique/success rates), nuclear medicine/scintigraphy (historic gold standard, current limitations).
• Recurrent LGIB: early vs. late rebleeding rates, risk factors, repeat evaluation.
• Small bowel/obscure GIB: definition, etiology, capsule endoscopy, double/single balloon enteroscopy, intraoperative enteroscopy.
• Surgery: indications (localization failure, instability), segmental vs. subtotal colectomy for non-localized bleeding, blind subtotal colectomy rebleeding rates.
• Fig. 40.9: full treatment algorithm for lower GI bleeding, from initial hematochezia presentation through discharge or surgical resection.

Open items / gaps

• Every named risk score, RCT (e.g. the urgent-vs.-standard colonoscopy timing trial), and outcomes figure in this chapter is cited at the textbook/secondary level only — see Lower Gastrointestinal Hemorrhage's own Open items for what would be highest-value to independently ingest first (the Oakland score, given its unique externally-validated status).
• Chapter 41 ("Endometriosis," Chua H, Snyder MJ) begins immediately after at book p. 715 — not yet read/ingested; only its colorectal-relevant framing (colon/rectal surgeons' involvement via combined procedures with gynecology) was visible in this read.