Chronic constipation is infrequent bowel movements for weak at a time. These are various type of diagnosis for chronic constipation like sigmoidoscope, colonoscopy, anorectal manometry and defecography. In sigmoidoscope procedure your doctor inserts a lighted, flexible tube into anus to examine rectum. In colonoscopy procedure allow the with flexible camera equipped tube. But in defecography your doctor inserted a soft paste in to rectum. This procedure is done only for X-ray.