GI bleeding

**Definition/Classification** - Upper GI bleed (UGIB): source proximal to the ligament of Treitz (duodenojejunal junction). Presents with hematemesis, coffee-ground emesis, melena (black, tarry, foul-smelling stool; needs ~50-100 mL of blood), or hematochezia if the bleed is brisk (~>1000 mL). - Lower GI bleed (LGIB): source distal to the ligament of Treitz (mostly colonic). Presents with hematochezia (bright red blood per rectum). - Occult GI bleed: not visible; detected by fecal occult blood test or iron deficiency anemia. - Obscure GI bleed: source remains unknown after EGD and colonoscopy; next steps are capsule endoscopy or enteroscopy.

**Common causes** - Upper: - Peptic ulcer disease (most common). Duodenal ulcers can erode the gastroduodenal artery (posterior wall). Gastric ulcers can erode the left gastric artery (lesser curvature). Risk factors include H. pylori, NSAIDs, and stress (Curling ulcer with burns, Cushing ulcer with CNS injury). - Esophageal varices (portal hypertension/cirrhosis) cause massive hematemesis. - Mallory-Weiss tear: mucosal laceration at the GE junction after forceful retching, classically in alcoholics or bulimia. - Boerhaave syndrome: full-thickness rupture, not primarily a bleeding lesion. - Erosive gastritis/esophagitis, Dieulafoy lesion, gastric cancer, AVMs, and aortoenteric fistula (prior aortic graft). - Lower: - Diverticulosis (most common cause of acute severe LGIB; painless, brisk bleed in an older adult). - Angiodysplasia (older adults, aortic stenosis = Heyde syndrome, and ESRD/von Willebrand disease). - Colorectal cancer/polyps (occult bleeding, change in bowel habits, and iron deficiency anemia in older adults). - Ischemic colitis (abdominal pain with bloody diarrhea in a watershed area, e.g., splenic flexure). - IBD (bloody diarrhea): ulcerative colitis (continuous, rectum up) vs. Crohn disease (skip lesions). - Hemorrhoids (bright red blood on toilet paper/stool surface; most common cause of minor hematochezia). - Anal fissure (painful, bright red blood). - Infectious colitis (EHEC, Shigella, Salmonella, Campylobacter, E. histolytica). - Pediatrics: Meckel diverticulum (painless hematochezia in a child; rule of 2s; ectopic gastric mucosa; Tc-99m pertechnetate scan), intussusception (currant jelly stool, colicky pain, sausage-shaped mass), and juvenile polyps.

**Pathophysiology/clinical consequences** - Hypovolemia leads to tachycardia, hypotension, orthostasis, and shock (class I-IV hemorrhage). - Hemoglobin may be normal early because of hemoconcentration; it falls after equilibration or IV fluids. - BUN:Cr ratio >20-30 suggests UGIB (blood protein digested and absorbed in the small bowel). - Hepatic encephalopathy can be precipitated in cirrhotics because the blood protein load increases ammonia.

**Workup** - Hemodynamic assessment and resuscitation first: 2 large-bore IVs, crystalloid, and type and cross. - Labs: CBC, BMP/BUN, coagulation studies (INR), and type and screen. - Transfuse pRBCs for a restrictive threshold of Hb <7 g/dL (<8 with cardiovascular disease). - Risk stratification: Glasgow-Blatchford score (need for intervention) and Rockall score. - UGIB: EGD within 24 h after stabilization (within 12 h for suspected variceal bleed is often cited). - LGIB: colonoscopy after bowel prep, typically within 24 h. If unstable and the source is unclear, use CT angiography, tagged RBC scan (slower bleeds, ~0.1-0.5 mL/min), or angiography (needs ~0.5-1 mL/min; allows embolization). - An NG tube is not routinely required. Bright red blood on NG lavage suggests an upper source.

**Management by etiology** - Peptic ulcer: IV PPI (high-dose), endoscopic therapy (epinephrine injection, cautery, clips) for high-risk stigmata (active bleeding, visible vessel), H. pylori testing/treatment, and stopping NSAIDs. Rebleeding can be treated with repeat endoscopy, then IR embolization or surgery. - Variceal bleed: IV octreotide (splanchnic vasoconstriction), antibiotic prophylaxis (ceftriaxone), endoscopic band ligation (first-line), and TIPS if refractory. Secondary prophylaxis is a nonselective beta-blocker (propranolol/nadolol) plus banding. Balloon tamponade (Sengstaken-Blakemore) is a temporizing measure. - Mallory-Weiss: usually self-limited; supportive care. - Diverticular/angiodysplasia: most stop spontaneously; use colonoscopic therapy, embolization, or surgery if recurrent. - Anticoagulant reversal: vitamin K/PCC/FFP for warfarin; andexanet alfa or idarucizumab (dabigatran) for DOACs where indicated. - Tranexamic acid is not recommended routinely in GI bleeding (HALT-IT trial showed no benefit and more venous thromboembolism).

**High-yield associations** - Melena = upper source (also from the small bowel/right colon with slow transit). Hematochezia = lower source (or a brisk upper bleed). - Painless hematochezia in an older adult: diverticulosis or angiodysplasia. - Aortoenteric fistula: a "herald bleed" in a patient with a prior aortic graft; CT, then surgery. - Hematemesis in an alcoholic with retching: Mallory-Weiss tear. Massive hematemesis in cirrhosis: varices. - Iron deficiency anemia in an older man or postmenopausal woman: rule out GI malignancy with EGD and colonoscopy. - Bismuth, iron, and charcoal can cause black stool without bleeding (guaiac-negative). - Hemorrhoids: internal (painless) vs. external (painful when thrombosed).