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Medicine > Gastrointestinal

Differential Diagnosis Schema 🧠

Upper Gastrointestinal Causes

Peptic Ulcer Disease: Commonest cause; history of NSAID use, Helicobacter pylori infection, or epigastric pain.
Gastritis or Erosive Gastropathy: Associated with alcohol use, NSAIDs, or stress; may present with epigastric discomfort.
Esophageal Varices: Seen in patients with liver cirrhosis; presents with hematemesis and significant bleeding.
Mallory-Weiss Tear: Often follows severe vomiting; presents with hematemesis.
Gastric Cancer: Risk factors include smoking, chronic gastritis; may have associated weight loss, anorexia.

Lower Gastrointestinal Causes

Diverticular Disease: Common in older adults; associated with left lower quadrant pain and altered bowel habits.
Colorectal Cancer: May present with changes in bowel habits, weight loss, or iron-deficiency anemia.
Inflammatory Bowel Disease: Ulcerative colitis or Crohn’s disease; may present with abdominal pain, diarrhea, and weight loss.
Hemorrhoids: Typically presents with fresh blood on wiping; usually painless unless thrombosed.

Other Causes

Anticoagulant Use: Can exacerbate bleeding from any source; important to consider in any patient on warfarin, DOACs, or antiplatelets.
Aortoenteric Fistula: Rare but life-threatening; consider in patients with a history of aortic graft surgery.
Angiodysplasia: Often asymptomatic, but can cause occult bleeding, particularly in the elderly.
Meckel’s Diverticulum: Consider in younger patients, typically painless bleeding.

Key Points in History 🥼

Symptomatology

Onset and Duration: Acute versus chronic symptoms help narrow differential diagnosis; for example, chronic pain may suggest peptic ulcer disease or malignancy.
Character and Color of Stool: Black, tarry stools suggest upper GI bleeding, while fresh red blood suggests lower GI sources.
Associated Symptoms: Weight loss, anorexia, and early satiety may suggest malignancy, while epigastric pain may suggest peptic ulcer disease.
Preceding Events: History of vomiting, NSAID or alcohol use, liver disease, or recent surgery can provide clues.
Bleeding Quantity: Large amounts of bleeding may indicate varices or major ulcers.

Background

Past Medical History: History of peptic ulcer disease, liver disease, or malignancy increases the likelihood of specific causes.
Drug History: Use of NSAIDs, anticoagulants, or antiplatelets raises suspicion for medication-induced bleeding.
Family History: Family history of GI cancers can point towards a hereditary predisposition.
Social History: Alcohol use is a significant risk factor for varices and gastritis, while smoking increases the risk of malignancy.
Recent Travel or Illness: Important for considering infections or stress ulcers.

Possible Investigations 🌡️

Laboratory Tests

Full Blood Count: Assess for anemia, thrombocytopenia, or leukocytosis; microcytic anemia may suggest chronic bleeding.
Liver Function Tests: Abnormalities may suggest liver disease as a source of bleeding.
Coagulation Profile: Essential in patients on anticoagulants or with suspected coagulopathy.
Urea: Raised urea with normal creatinine can suggest upper GI bleeding.
Group and Save/Crossmatch: Important for patients with significant bleeding requiring transfusion.

Imaging and Endoscopy

Upper Endoscopy (OGD): Gold standard for diagnosing upper GI sources; allows for direct visualization and potential treatment of bleeding sites.
Colonoscopy: Used to evaluate the lower GI tract; important for diagnosing colorectal cancer, diverticular disease, and IBD.
CT Angiography: Useful for detecting active bleeding and vascular abnormalities, particularly in obscure cases.
Capsule Endoscopy: Consider for small bowel sources not identified by other means; useful in diagnosing conditions like Meckel’s diverticulum.

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