• Hematemesis, coffee ground emesis, prior UGI bleed, melena, underlying cirrhosis, NSAID use, hemodynamically significant bleeding

• Clinicians assign a pre-test probability to their potential diagnoses using the epidemiology/base rate of the disease, the characteristics/demographics of the patient, and the presenting signs/symptoms
  • For example, a study of 2.4 million patients in the United States with UGI bleeding found the following prevalences that can be used as a starting point for pretest probabilities for patients with UGI bleeding even before seeing the patient: peptic ulcer disease 47%; gastritis 18%; esophagitis 15%; Mallory Weiss Tear 6%; angiodysplasia 6%; neoplasm 4%; esophageal varices 2% (other studies showed varices up to 10%)

• The pretest probability is constantly updated with the application of additional knowledge about the patient (i.e., if a patient has cirrhosis, the likelihood of a variceal bleed increases significantly)

• Illness scripts: An illness script is a mental representation of a disease that we build in our mind that includes the epidemiology, pathophysiology, clinical features, and treatment of the disease. We match a patient’s presentation to the illness script in making a diagnosis.

Key Clinical Learning Points

• Know the most common and “can’t miss” causes of upper GI bleeding
  • Most common: Peptic ulcer disease (gastric/duodenal ulcers), gastritis, esophagitis, Mallory Weiss Tears, angiodysplasia, malignancy, varices
  • “Can’t miss “diagnoses: esophagogastric varices, cancer

• Know the common and “can’t miss” causes of lower GI bleeding
  • Diverticulosis, hemorrhoids, colitis, angiodysplasia, malignancy

• Questions to ask in a patient with GIB
  • Frequency of bleeding (helps with severity)
  • Character of the bleeding (hematochezia, hematemesis, coffee-ground emesis, melena; volume of each)
  • Onset (the acute/sub-acute/chronic differentiation has a big impact on the differential diagnosis)
  • Presence of abdominal pain (e.g. ulcers are usually painful, varices are not; colitis)
  • NSAID use (for peptic ulcer disease)
  • Liver disease or risk factors for it like alcohol use and hepatitis (for varices)
  • Alcohol use (for gastritis)
  • Vomiting/retching preceding hematemesis (for Mallory-Weiss tear)
  • GERD symptoms (for esophagitis)
  • Prior aortic surgery (for aorto-enteric fistula)
  • Vascular disease (for ischemic colitis)
  • Fever (for colitis)
  • Orthostatic symptoms (helps determine the severity of the bleed)

•  What to look for on exam in a patient with GIB
  • Evidence of anemia:
    • conjunctival pallor (LR+ 4.7, LR- 0.6), palmar crease pallor (LR+ 7.9), pallor at any site (LR+ 3.8, LR- 0.5)
  • Abdominal tenderness (including peritoneal signs, although most causes of GI bleeding do not cause peritonitis; peptic ulcer disease and ischemic colitis may present with concomitant abdominal pain and gastrointestinal bleeding),
  • Evidence of cirrhosis (e.g., jaundice, splenomegaly, palmar erythema, spider telangiectasias, ascites, asterixis, cherry red spots)
  • Presence of melena or bright red blood on rectal exam

• The key features of the clinical history and exam that differentiate upper and lower sources of bleeding (repeated from above):
  • Upper source: hematemesis, coffee ground emesis, prior UGI bleed, melena, underlying cirrhosis, NSAID use, hemodynamically significant bleeding
  • Lower source: prior LGI bleed, hematochezia especially with clots, and lower abdominal pain

• Key distinction: 10% of patient with hematochezia have an upper source and often have a very rapid and likely life-threatening bleed. Hemodynamic instability, melena, and cirrhosis all make an upper source more likely in a patient presenting with hematochezia.

Table 1. Useful likelihood ratios in evaluating a patient with gastrointestinal bleeding (repeated from above as basis for pre-class discussion question)

Table 2 Differential diagnosis of lower GI bleeding

Table 3. Differential diagnosis of upper GI bleeding

A 75 year old female with a history of aortic stenosis and coronary artery disease presents with passage of a large volume of blood from below.  She has no history of gastrointestinal bleeding and was feeling well until she developed crampy lower abdominal discomfort.  This was followed by the passage of a significant amount of bright red blood mixed in with a minimal amount of brown stool.  She denies melena, change in stool, lightheadedness and hematemesis.  The abdominal cramping was relieved by passing the blood.  Vital signs are normal with no orthostatic changes and exam reveals only a murmur consistent with aortic stenosis. [colonic angiodysplasia, could also be a diverticular bleed]

A 56 year old male presents with melena and hematochezia.  He has a history of hypertension and osteoarthritis for which he takes hydrochlorothiazide and naproxen.  He was well until yesterday when he noted onset of dull epigastric discomfort followed by several black, tarry and foul-smelling stool.  This morning he passed another tarry stool which had a small amount of bright red blood mixed in.  He also feels lightheaded.  On exam, he is hypotensive and tachycardic and has modest epigastric tenderness without rebound or guarding. Stool exam shows black tarry stool with a small amount of bright red blood. [Peptic ulcer disease]

A 77 year old male presents with hematemesis.  He has a history of coronary artery disease, hypertension and abdominal aortic aneurysm for which he underwent repair six years prior.  This morning vomited a modest amount of blood but now feels back to baseline. He denies melena, hematochezia, abdominal pain and lightheadedness.  Medications include metoprolol, simvastatin, lisinopril and mini-dose aspirin.  [Aorto-enteric fistula]

An 82 year old female with a history of hypertension and dyslipidemia presents with blood in her stool. She has intermittently noted small amounts of blood mixed in with her stool for the last six months.  There has been no abdominal pain, melena, or other changes in stool.  Physical exam, including rectal exam is unremarkable.  Stool guaiac is strongly positive although there is no gross blood.  Laboratories show a hemoglobin on 8.5 with an MCV of 72. [Colon cancer]