Final answer:
A patient with lower gastrointestinal bleeding should be prepared for a colonoscopy, which can diagnose and treat conditions such as colorectal cancer or polyps.
Step-by-step explanation:
When a patient experiences lower gastrointestinal bleeding, the most appropriate diagnostic study to prepare the patient for is a colonoscopy. This procedure is both diagnostic and therapeutic, allowing for the examination of the colon to identify possible causes for bleeding such as colorectal cancer, polyps, or inflammatory bowel disease. During a colonoscopy, a tiny camera is inserted through an endoscope into the colon, providing a visual inspection that can help identify and potentially remove precancerous polyps, thereby preventing them from becoming malignant. Additional tests like fecal occult blood tests may also be recommended to check for hidden blood in the stool.