The aim of this study is to determine if performing early colonoscopy in patients who present to the hospital with lower GI bleeding improves their outcome.~Patients who are admitted with bleeding from their rectum and clinical evidence of a significant bleeding episode (elevated heart rate, low blood pressure, or need for blood transfusion) have immediate upper endoscopy (examination of the stomach with a flexible rubber tube with a light and video camera on the end). If this shows no source of bleeding, the patients are randomized (like flipping a coin) to receive a colonsoscopy (examination of the large intestine with a flexible rubber tube with a light and video camera on the end) either as a emergency (within 12 hours) or as a routine procedure (36 hours after admission).~Patients are followed during their hospitalization to see if they have further bleeding, if they require blood transfusions, if they need other diagnostic tests, if they need surgery or other treatments, and how long they stay in the hospital.
Study hypothesis is that performing early colonoscopy in patients who present to the hospital with lower GI bleeding improves their outcome.~Patients who are admitted with bleeding from their rectum and a negative endoscopic exam of the stomach and upper intestine are randomized (like flipping a coin) to receive a colonsoscopy either as an emergency (within 12 hours) or as a routine procedure (36 hours after admission). Patients are followed during their hospitalization to see if they have further bleeding, if they require blood transfusions, if they need other diagnostic tests, if they need surgery or other treatments, and how long they stay in the hospital.