Sigmoidoscopy: Endoscopic examination, therapy or surgery of the sigmoid flexure.Sigmoidoscopes: Endoscopes for examining the interior of the sigmoid colon.Colonoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the colon.Enema: A solution or compound that is introduced into the RECTUM with the purpose of cleansing the COLON or for diagnostic procedures.Occult Blood: Chemical, spectroscopic, or microscopic detection of extremely small amounts of blood.Barium Sulfate: A compound used as an x-ray contrast medium that occurs in nature as the mineral barite. It is also used in various manufacturing applications and mixed into heavy concrete to serve as a radiation shield.Colorectal Neoplasms: Tumors or cancer of the COLON or the RECTUM or both. Risk factors for colorectal cancer include chronic ULCERATIVE COLITIS; FAMILIAL POLYPOSIS COLI; exposure to ASBESTOS; and irradiation of the CERVIX UTERI.Mass Screening: Organized periodic procedures performed on large groups of people for the purpose of detecting disease.Rectal Diseases: Pathological developments in the RECTUM region of the large intestine (INTESTINE, LARGE).Diverticulum, Colon: A pouch or sac opening from the COLON.Intestinal Polyps: Discrete abnormal tissue masses that protrude into the lumen of the INTESTINE. A polyp is attached to the intestinal wall either by a stalk, pedunculus, or by a broad base.Colonic Polyps: Discrete tissue masses that protrude into the lumen of the COLON. These POLYPS are connected to the wall of the colon either by a stalk, pedunculus, or by a broad base.Adenomatous Polyps: Benign neoplasms derived from glandular epithelium. (From Stedman, 25th ed)Fiber Optic Technology: The technology of transmitting light over long distances through strands of glass or other transparent material.Colonic Diseases: Pathological processes in the COLON region of the large intestine (INTESTINE, LARGE).Rectum: The distal segment of the LARGE INTESTINE, between the SIGMOID COLON and the ANAL CANAL.Adenoma: A benign epithelial tumor with a glandular organization.Early Detection of Cancer: Methods to identify and characterize cancer in the early stages of disease and predict tumor behavior.Sigmoid Neoplasms: Tumors or cancer of the SIGMOID COLON.Rectal Neoplasms: Tumors or cancer of the RECTUM.Proctoscopy: Endoscopic examination, therapy or surgery of the rectum.Proctitis: INFLAMMATION of the MUCOUS MEMBRANE of the RECTUM, the distal end of the large intestine (INTESTINE, LARGE).Gastrointestinal Hemorrhage: Bleeding in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Indigo Carmine: Indolesulfonic acid used as a dye in renal function testing for the detection of nitrates and chlorates, and in the testing of milk.Organizations, Nonprofit: Organizations which are not operated for a profit and may be supported by endowments or private contributions.Insurance Carriers: Organizations which assume the financial responsibility for the risks of policyholders.Colon, Sigmoid: A segment of the COLON between the RECTUM and the descending colon.Gastroenterology: A subspecialty of internal medicine concerned with the study of the physiology and diseases of the digestive system and related structures (esophagus, liver, gallbladder, and pancreas).Picolines: A group of compounds that are monomethyl derivatives of pyridines. (From Dorland, 28th ed)Observational Study as Topic: A clinical study in which participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study).Polyps: Discrete abnormal tissue masses that protrude into the lumen of the DIGESTIVE TRACT or the RESPIRATORY TRACT. Polyps can be spheroidal, hemispheroidal, or irregular mound-shaped structures attached to the MUCOUS MEMBRANE of the lumen wall either by a stalk, pedunculus, or by a broad base.Hemorrhoids: Swollen veins in the lower part of the RECTUM or ANUS. Hemorrhoids can be inside the anus (internal), under the skin around the anus (external), or protruding from inside to outside of the anus. People with hemorrhoids may or may not exhibit symptoms which include bleeding, itching, and pain.Proctocolitis: Inflammation of the RECTUM and the distal portion of the COLON.Colonic Neoplasms: Tumors or cancer of the COLON.Colonography, Computed Tomographic: A non-invasive imaging method that uses computed tomographic data combined with specialized imaging software to examine the colon.Cathartics: Agents that are used to stimulate evacuation of the bowels.Endoscopy, Gastrointestinal: Endoscopic examination, therapy or surgery of the gastrointestinal tract.Sigmoid Diseases: Pathological processes in the SIGMOID COLON region of the large intestine (INTESTINE, LARGE).Intestinal Perforation: Opening or penetration through the wall of the INTESTINES.United StatesColon: The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.