2 large bore IVs (or sheath introducer)
Type and cross
CBC & serial hemoglobin
Chemistry
BUN/creatinine >30 suggests UGI if no history of renal failure (increased absorption/digestion of hb)
Coags
LFTs
Fibrinogen
Guiac
More useful for diagnosing chronic occult bleeding (it could be positive for up to 2 weeks after an acute bleed)
False-positive: vitamin C, red meat, methylene blue, bromide preparations, turnips, horseradish
ECG (if >40 yo or if suspicious for silent MI, especially from demand ischemia)
CXR (if suspect perforation)
BUN/creatinine >30 suggests UGI if no history of renal failure (increased absorption/digestion of hb)
More useful for diagnosing chronic occult bleeding (it could be positive for up to 2 weeks after an acute bleed)
False-positive: vitamin C, red meat, methylene blue, bromide preparations, turnips, horseradish
Pros
Positive aspirate proves strong<unk> idence for an upper GI source of bleeding
Can assess presence of ongoing active bleeding
Can prepare patient for endoscopy
Cons
Uncomfortable
Negative aspirate does not conclusively exclude upper GI source
Provides useful information in only minority of patients without hematemesis
Erythromycin 200mg IV can provide equal endoscopy conditions as lavage
Positive aspirate proves strong<unk> idence for an upper GI source of bleeding
Can assess presence of ongoing active bleeding
Can prepare patient for endoscopy
Uncomfortable
Negative aspirate does not conclusively exclude upper GI source
Provides useful information in only minority of patients without hematemesis
Erythromycin 200mg IV can provide equal endoscopy conditions as lavage
Esophageal varices
Peptic ulcer disease 
Mallory-Weiss tear
Gastritis/esophagitis
Esophageal candidiasis
Gastric/esophageal varices
Achalasia
Esophagitis