Investigation of choice in upper GI bleeding is

"Upper endoscopy is the test of choice in patients with UGIB" "Whenever GI haemorrhage is thought to derive from a source proximal to the ligament of Treitz, or whenever the issue is in doubt, the first invasive diagnostic maneuvre should be upper GI flexible endoscopy. This technique has a diagnostic accuracy of approximately 95% and an overall complication rate of less than 1%. Endoscopy also allows a qualitative assessment of bleeding rate, provides prognostic information regarding rebleeding potential, and offers numerous therapeutic interventions for specific lesions" - maingot's 10/e, p 291 Other investigations for Upper GI bleedingAngiography (Celiac axis angiography) it is rarely used, when upper endoscopy is unavailable or nonrevealing and the bleeding site still thought to be proximal to the ligament of Treitz. it also has the potential for therapeutic intervention by embolization of the feeding vessel. Barium study "Barium contrast radiography is no longer peinent to the diagnosis of acute hemorrhage. It should be reserved for those patients with chronic or intermittent bleeding that probably is due to an ulcer or mass lesion." Ref : CSDT 13/e p494 , Harrison 17/e p259