Tests for constipation may include; blood tests and sigmoidoscopy- this procedure involves using a narrow, flexible, tube-like telescope(a sigmoidoscope) to look inside the rectum and lower part of the bowel, colonoscopy- this involves using a narrow, flexible, tube-like telescopic camera(a colonoscope) to look inside the large bowel, a Barium enema X-ray-this test involves placing a fluid containing barium(a substance which shows up on X-rays) into the bowel via the rectum. X-ray images of the abdomen then show the inside of the bowel more clearly.
Attribution: BUPA