The colon is below the cecum and above the rectum, i.e., the main body of the large intestine. The colon includes four parts: ascending colon, transverse colon, descending colon, and sigmoid colon, which are arranged in an M-shape in the abdominal cavity. The total length of the colon is about 1.3-1.4m, and the body projection is located in the right abdomen, right upper abdomen, upper abdomen, left upper abdomen, left abdomen, and finally to the left lower abdomen. The lower part of the ascending colon is connected to the cecum, and the ascending colon segment is approximately 12-20 cm, below the liver, and connected to the transverse colon. The transverse colon is the longest and most mobile part of the colon, roughly 40-50 cm, and is connected to the ascending colon in the hepatic region and to the descending colon in the splenic region. The descending colon is roughly 20 cm, usually under the spleen, and is connected to the transverse colon and to the sigmoid colon below. The sigmoid colon has a large variation in length in the pelvis, about 20-70 cm, and is located between the descending colon and rectum, and is called sigmoid colon because of its sigmoid shape.