GI bleeding

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

• The Core Mechanism: Gastrointestinal bleeding is anatomically divided into upper and lower tracts, delineated by the ligament of Treitz. The presentation is driven by either mucosal erosion, vascular distension, or mechanical shearing.
• The Cellular Breakdown: In upper GI bleeding (UGIB), highly acidic environments degrade the gastric or duodenal mucosa, exposing and eroding underlying arterial beds (Peptic Ulcer Disease). In patients with liver cirrhosis, progressive fibrosis restricts venous outflow, causing portal hypertension; this severely elevates pressures in the portosystemic collaterals, leading to fragile, engorged esophageal varices that are highly prone to catastrophic rupture.
• The Fatal Cascade: As massive blood loss occurs, intravascular volume drops drastically, impairing venous return (preload) and decreasing cardiac output. When blood loss exceeds 30% to 40% of the total blood volume, the compensatory mechanisms fail, resulting in profound hemorrhagic shock, generalized tissue hypoxia, and imminent cardiovascular collapse.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• Immediate Stabilization: Secure the ABCs, place the patient on continuous cardiac monitoring, and establish at least two large-bore intravenous (IV) catheters.
• Airway Management: Patients with massive UGIB, altered mental status, or respiratory distress require early intubation for airway protection. However, you must optimize hemodynamic status prior to administering induction drugs and initiating positive pressure ventilation to mitigate the severe drop in cardiac output that can precipitate sudden circulatory arrest.
• Fluid & Blood Resuscitation: For patients with active bleeding and signs of impending hemodynamic compromise, rapidly infuse 2 Liters of balanced isotonic crystalloid over the first 30 minutes. If the patient is critically unstable with a massive bleed, immediately initiate uncrossmatched packed red blood cells (PRBCs).
• Transfusion Targets: Transfuse PRBCs for a hemoglobin $\le$ 7 g/dL in most patients, or $\le$ 9 g/dL in older patients or those with severe comorbidities. If a massive transfusion is required, implement a 1:1:1 ratio of PRBCs, platelets, and fresh frozen plasma (FFP).
• Pharmacotherapy: Administer intravenous Proton Pump Inhibitors (PPIs) for UGIB, which are proven to decrease rebleeding, surgical requirement, and mortality.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

• "Can't-Miss" Mimics & Etiologies:
• Aortoenteric Fistula: A rare but fatal cause of bleeding classically presenting as a self-limited "herald" bleed followed by massive exsanguination, exclusively seen in patients with a prior aortic graft.
• Esophageal Varices: The highest mortality cause of UGIB; heavily suspected in patients with a history of liver disease or physical stigmata like jaundice, ascites, or acholic stools.
• Mallory-Weiss Tear: Suspect when non-bloody vomiting or forceful retching directly precedes the onset of hematemesis.
• Peptic Ulcer Disease (PUD): The most common etiology of UGIB, often triggered by NSAIDs, salicylates, or alcohol abuse.
• Prioritized Diagnostic Workup:
• Lactate Level: Obtain an initial lactate; a level > 2.5 mmol/L is highly predictive of in-hospital hypotension and increased 30-day mortality.
• CBC and Coagulation Panel: An initial hemoglobin < 10 g/dL or an INR > 1.5 is predictive of increased inpatient mortality and the need for ICU admission.
• CT Angiography (CTA): The gold-standard imaging modality for hemodynamically unstable patients with brisk lower GI bleeding (LGIB) to localize the exact vascular source prior to embolization.
• Digital Rectal Examination: Mandatory to assess for melena (indicating UGIB) or hematochezia (indicating LGIB or extremely brisk UGIB).

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

• Visual Inspection: Direct visual inspection of the vomitus for a bloody, maroon, or "coffee-ground" appearance remains the most reliable bedside method to diagnose upper GI bleeding in the ED.
• ECG Findings: Always perform a 12-lead ECG on any patient over 50 years old or with massive hemorrhage. Profound anemia and hypovolemia can unmask or induce occult myocardial ischemia, leading to ischemic ST-segment or T-wave changes.
• CT Angiography (CTA): In massive LGIB, look for the definitive "blush" of active contrast extravasation into the bowel lumen, which directs the interventional radiologist to the target vessel.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

• The Shock Index: Calculated as Heart Rate divided by Systolic Blood Pressure. A Shock Index $\ge$ 0.9 in the setting of active hematemesis or hematochezia defines a "massive" GI bleed, mandating immediate uncrossmatched blood transfusion.
• The Glasgow-Blatchford Score (GBS): A validated risk-stratification tool utilized to identify low-risk UGIB patients who can be safely discharged for outpatient endoscopy, versus high-risk patients requiring hospital or ICU admission.
• ED Observation Exclusions: Patients with unstable vital signs, orthostatic hypotension, more than two episodes of bright red bleeding, a hemoglobin drop >10 in 4 hours, or a history of end-stage liver disease/varices are strictly excluded from ED observation units.

6. THE DANGER ZONE (Pitfalls & Critical Actions)

• Deadly Cognitive Trap (Vital Sign Reliance): Relying strictly on tachycardia to rule in hypovolemia. Correction: Paradoxical bradycardia can occur despite profound hypovolemia. Furthermore, patients on beta-blockers cannot mount a tachycardic response, and baseline hypertension may mask significant hypotensive drops.
• Deadly Cognitive Trap (Coagulation Correction): Reflexively administering FFP to correct an elevated INR in a cirrhotic patient with a GI bleed. Correction: Routine administration of FFP or PCCs in liver failure does not reliably reduce bleeding and can paradoxically worsen portal hypertension, exacerbating the variceal hemorrhage and increasing thrombotic risk. Only use these products if executing a massive transfusion protocol.
• Procedural Pitfall (Routine NGT): Placing a nasogastric tube (NGT) in all patients with suspected UGIB. Critical Action: Routine NGT placement is no longer recommended; it causes severe discomfort, carries complication risks, and fails to reliably provide useful data to alter management.

7. MCQ MASTERCLASS (Written Exam Tips)

• High-Yield Buzzwords: "Coffee-ground emesis" definitively points to an upper GI bleed altered by gastric acid. "Herald bleed" preceding massive hemorrhage is the classic hallmark of an aortoenteric fistula.
• Diagnostic Distractor: A question asks for the immediate next step in a patient presenting with coffee-ground emesis and stable vitals. The distractor is "Placement of a nasogastric tube for gastric lavage." Correction: Skip the NGT; it is outdated and unsupported by literature. Choose options centered on PPI administration or gastroenterology consultation.
• The Fluid Pitfall: An elderly patient presents with massive melena and a blood pressure of 70/40. The distractor suggests "Intubate immediately for airway protection." Correction: While airway protection is vital, the correct immediate step is volume resuscitation (fluids and blood), as induction agents in an un-resuscitated patient will cause immediate cardiac arrest.

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

• The Initial Assessment Hook: "Given the patient's presentation of massive hematemesis, coffee-ground emesis, and an elevated shock index, I am highly concerned for a life-threatening upper GI bleed, with a differential including peptic ulcer disease, Mallory-Weiss tear, or bleeding esophageal varices."
• The Resuscitation Command: "I will immediately establish two large-bore IVs and initiate a rapid 2-liter infusion of balanced isotonic crystalloid. Because the patient is hemodynamically unstable, I am calling for uncrossmatched packed red blood cells. If bleeding continues, I will activate the massive transfusion protocol at a 1:1:1 ratio."
• The Definitive Disposition: "I am ordering intravenous proton pump inhibitors and checking an initial lactate to assess mortality risk. I will purposefully defer nasogastric tube placement as it is not clinically indicated. Once hemodynamically optimized, I will secure the airway if needed, and consult gastroenterology emergently for an upper endoscopy in the Intensive Care Unit."