Laboratory Findings in gastrointestinal bleeding

• Complete blood count: Mild leucocytosis and thrombocytosis develop within 6 hrs after the onset of bleeding.
• Card test:this is useful for detection of occult blood in stools.
• Endoscopy: It is useful for confirmation and treatment in more than 90% of cases.The risk of of rebleeding is higher if a 'visible vessel' is seen in ulcer crater.
• Angiography: It is useful to detect the exact  site of bleeding (>0.5 ml/min).
• Radio-labelled RBC: It is useful in determining low grade bleeding from gastrointestinal tract and especially when the pathology is out of reach of the endoscope (>0.1 ml/min).