Bleeding originating proximal to ligament of Treitz
In the acute setting, the hemoglobin/hematocrit may be normal until dilutional anemia appears after volume resuscitation
Older patients -> peptic ulcer disease, esophagitis, gastritis; younger patients -> Mallory-Weiss tears, GI varices, gastropathy
Peptic ulcer disease = 4%
Variceal bleeding = 50%
Medications
ASA, steroids, anticoagulants, chemotherapeutic agents
NSAIDs
RR of bleeding for COX-1 inhibitors is 4.5 (3.82-5.31)
RR of bleeding for COX-2 inhibitors is 1.88 (0.96-3.71)
ETOH abuse
Peptic ulcer disease, gastritis, varices
Aortic graft = aortoenteric fistula
Advanced age (>60 yr)
Current smoker
ASA, steroids, anticoagulants, chemotherapeutic agents
NSAIDs
RR of bleeding for COX-1 inhibitors is 4.5 (3.82-5.31)
RR of bleeding for COX-2 inhibitors is 1.88 (0.96-3.71)
RR of bleeding for COX-1 inhibitors is 4.5 (3.82-5.31)
RR of bleeding for COX-2 inhibitors is 1.88 (0.96-3.71)
Peptic ulcer disease, gastritis, varices
Undifferentiated upper gastrointestinal bleeding
Peptic ulcer disease 
Lower gastrointestinal bleeding
Gastritis/esophagitis
Acute gastric dilatation
Gastric/esophageal varices
Splenic infarction
Mallory-Weiss tear