What is the recommended initial procedure for diagnosing lower gastrointestinal bleeding?

The recommended initial procedure for diagnosing lower gastrointestinal bleeding is colonoscopy because it allows for direct visualization of the colon, which is essential for identifying the source of bleeding in cases related to the lower gastrointestinal tract. During a colonoscopy, the entire colon can be examined, and if necessary, biopsies can be taken or therapeutic interventions can be performed at the same time, such as cauterizing bleeding vessels or removing polyps.

This procedure is particularly effective because it helps to differentiate between various causes of lower GI bleeding, such as diverticulosis, colorectal cancer, or inflammatory bowel disease. Additionally, colonoscopy can often be performed urgently, depending on the patient's condition, making it a suitable choice in acute scenarios.

Other imaging modalities like CT scans can be useful for assessing gastrointestinal bleeding, but they typically do not provide the same level of information about the mucosal surface or allow for therapeutic action. Endoscopy is primarily used for upper gastrointestinal tract issues, and while ultrasound can be helpful in some scenarios, it is less effective for directly diagnosing lower GI bleeding.