📚 Gastroenterology (Git) — L1: Gastrointestinal Bleeding

📚 Lecture Overview

This lecture covers the pathophysiology, clinical presentation, and comprehensive management of Gastrointestinal Bleeding (GIB), categorized into Upper GIB, Lower GIB, and Obscure/Small Bowel GIB. Understanding these protocols is critical for clinicians to rapidly assess hypovolemia, perform targeted resuscitation, and utilize endoscopic or radiological interventions to reduce morbidity and mortality.

🎯 Key Concepts & Definitions

• Ligament of Treitz: The anatomical landmark that divides Upper GIT bleeding (proximal) from Lower GIT bleeding (distal).
• Hematemesis: Vomiting of bright red blood or coffee-ground material, indicating bleeding proximal to the ligament of Treitz.
• Melena: Black, tarry stools resulting from the degradation of blood by digestive enzymes as it passes through the GI tract.
• Hematochezia: Passage of fresh, bright red blood per rectum, typically signifying lower GI bleeding or rapid upper GI bleeding.
• Shock Index: The ratio of heart rate to systolic blood pressure ($HR / SBP$), where a value $>1$ indicates hemodynamic instability.
• Glasgow Blatchford Score (GBS): A risk-stratification scoring system used in upper GI bleeding; a score $≤ 1$ indicates very low risk and suitability for outpatient management.
• Oakland Score: A risk assessment tool used in lower GI bleeding; a score $≤ 8$ predicts a high probability of safe patient discharge.
• Forrest Classification: A standardized endoscopic grading system for peptic ulcers that predicts rebleeding risk based on stigmata of hemorrhage (ranging from active spurting to a clean-based ulcer).
• Small Bowel Bleeding (Obscure GIB): Bleeding of unknown origin that persists or recurs after an initial negative bidirectional endoscopy (gastroscopy and colonoscopy), typically originating between the Ampulla of Vater and the ileocaecal valve.

📖 Main Content

Upper Gastrointestinal Bleeding (UGIB)

• Definition & Etiology: Bleeding occurring proximal to the ligament of Treitz. Major causes include:
• Complications of portal hypertension: Gastro-esophageal varices, portal hypertensive gastropathy, and isolated gastric varices.
• Ulcerative or erosive causes: Peptic ulcers (H. pylori, NSAIDs, stress, Zollinger-Ellison syndrome), GERD, and pill-induced esophagitis.
• Traumatic causes: Mallory-Weiss tear and Cameron ulcer.
• Vascular lesions: Angiodysplasias, Dieulafoy lesion, and Gastric antral vascular ectasia (GAVE).
• Tumors: Benign (leiomyoma, polyps) and malignant (adenocarcinoma, GI stromal tumors, lymphoma).
• Initial Assessment & Resuscitation:
• Assess hypovolemia via vital signs: Resting tachycardia ($≥ 100$ bpm) indicates mild-moderate loss; hypotension ($SBP < 100$ mmHg) indicates $\sim 40%$ blood volume loss; orthostatic changes indicate $≥ 15%$ loss.
• Insert two large-bore cannulas (gauge 14-18) and administer crystalloids or plasma expanders to target $SBP > 100$ mmHg and pulse $< 100$ bpm.
• Restrict oral intake (nothing per mouth); consider endotracheal intubation in patients with ongoing hematemesis or altered mental status to prevent aspiration.
• Pharmacological & Endoscopic Management:
• Variceal bleeding: Initiate vasoactive drugs (Terlipressin 1-2 mg IV every 4 hours, or Octreotide/Somatostatin) and short-term antibiotic prophylaxis (oral norfloxacin or IV ceftriaxone). Perform diagnostic endoscopy within 24 hours. Use band ligation for esophageal varices and cyanoacrylate injection for gastric varices.
• Non-variceal bleeding: Administer high-dose IV Proton Pump Inhibitor (PPI) (80 mg loading dose, then 8 mg/hr infusion). Utilize endoscopic combination therapy (e.g., epinephrine injection plus thermal contact or hemoclips) for high-risk Forrest ulcers (IA, IB, IIA). Use TIPS (Transjugular Intrahepatic Portosystemic Shunt) for refractory variceal bleeding.

Lower Gastrointestinal Bleeding (LGIB)

• Definition & Epidemiology: Bleeding originating from the colon, rectum, or anus, accounting for roughly $20%$ of all GI bleeds.
• Etiology: Diverticular disease of the colon, angiodysplasia, neoplasms, Inflammatory Bowel Disease (IBD), ischemic/infectious colitis, radiation proctitis, and anorectal diseases (hemorrhoids, fissures).
• Management & Risk Stratification:
• Calculate Shock Index ($Heart Rate / Systolic BP$); unstable patients ($Index > 1$) require immediate resuscitation and CT angiography (CTA) to localize the bleed.
• If CTA is negative or unavailable in unstable patients, perform immediate upper endoscopy because 8-9% of apparent lower GI bleeds actually originate from an upper GI source.
• Colonoscopy should be performed semi-electively (after bowel preparation) for stable patients. High-risk diverticular or post-polypectomy bleeds can be managed with epinephrine injection combined with thermal coagulation or hemoclips. Avoid monopolar electrocautery in poorly prepped colons due to explosion risks from flammable gas.
• Alternative Imaging: Technetium-99m tagged red blood cell radionuclide scintigraphy detects bleeding rates as low as $0.04$ mL/min. Mesenteric angiography requires a higher bleeding rate ($>0.5$ mL/min) but offers therapeutic superselective arterial embolization.

Obscure / Small Bowel Gastrointestinal Bleeding

• Definition: Overt or occult bleeding of unknown origin persisting after negative bidirectional endoscopies. Comprises $\sim 5%$ of all GI hemorrhages, with $>80%$ originating in the small bowel.
• Diagnostic Tools:
• Capsule Endoscopy (VCE): Recommended as the first-line examination for suspected small-bowel bleeding due to its high safety profile and mucosal visualization. Must be performed ideally within 48 hours for overt bleeding.
• Device-Assisted Enteroscopy: Allows both visual diagnosis and therapeutic intervention (biopsy, cautery) in the same procedure.
• CT or MR Enterography: Utilizes IV contrast and oral mannitol to detect inflammation, mural stratification, and luminal narrowing.
• Contraindications for VCE: Known/suspected GI obstruction, strictures, motility disorders, cardiac pacemakers, swallowing disorders, and pregnancy.

📊 Visual Learning

💡 Important Points to Remember

• The Ligament of Treitz divides upper GI bleeding from lower GI bleeding.
• Resting Tachycardia ($≥ 100$ bpm) signals mild-moderate hypovolemia; Hypotension ($SBP < 100$ mmHg) indicates a $\sim 40%$ blood volume loss.
• Shock Index formula: $Heart Rate / Systolic BP$. A value $>1$ indicates hemodynamic instability.
• Glasgow Blatchford Score $≤ 1$ allows safe outpatient management for UGIB.
• Oakland Score $≤ 8$ predicts a 95% probability of safe discharge for LGIB patients.
• High-risk ulcers (Forrest IA, IB, IIA) require dual endoscopic therapy (e.g., epinephrine injection plus clipping or thermal coagulation).
• Variceal bleeding protocol: Administer Terlipressin immediately, start antibiotic prophylaxis (e.g., ceftriaxone or norfloxacin), and perform endoscopy within 24 hours.
• Forrest III clean-based ulcers carry a very low rebleeding risk and do not require endoscopic hemostasis.
• Capsule Endoscopy is the gold standard first-line test for small bowel bleeding, but it is strictly contraindicated in suspected bowel obstructions.
• Common Mistake: Forgetting that 8-9% of patients presenting with apparent lower GI bleeding and hemodynamic instability actually have an upper GI bleeding source.

⚠️ Common Exam Questions

• MCQ Trap: Examiners often present a patient with hematochezia and hemodynamic instability, tempting students to choose an immediate colonoscopy. The correct answer is to perform upper endoscopy or CT angiography first, as brisk upper GI bleeding can present as hematochezia.
• Management Traps: Questions will test whether to stop aspirin or anticoagulants in bleeding patients. Remember current guidelines: do not routinely interrupt low-dose aspirin for secondary cardiovascular prevention, but temporarily withhold DOACs or therapeutic anticoagulants during major acute bleeds.
• Forrest Classification Identification: Expect matching questions where you must link ulcer appearance (e.g., spurting vessel vs. clean-based ulcer) to the appropriate intervention intensity (dual therapy vs. medical management alone).

📝 Quick Review Checklist

I can define the anatomical boundary between upper and lower GIB
I understand how to calculate and interpret the Shock Index
I can differentiate between management protocols for variceal and non-variceal upper GIB
I know the indications and contraindications for capsule endoscopy
I can interpret Forrest classifications for peptic ulcers and their required treatments
I understand when to use CT angiography versus colonoscopy in lower GIB