Digestive problems can occur for a variety of reasons. A structural gastrointestinal disease is one in which the bowel does not work properly as well as looks abnormal upon examination. Surgical removal of structural abnormalities is sometimes necessary. Structured GI diseases include strictures, hemorrhoids, stenosis, diverticular disease, colon cancer, colon polyps, and inflammatory bowel disease. You experience constipation if you are unable to pass stools, if the stools are infrequent (less than three times a week), or if the stools are incomplete. Inadequate "roughage" or fiber in your diet can cause constipation, as can disruptions in your routine. During a bowel movement, you strain when you are constipated. It can cause hard, small stools and sometimes anal problems such as hemorrhoids and fissures. You are not likely to have a more serious medical condition if you experience constipation. Irritable bowel syndrome (also known as spastic colon, irritable colon, IBS, or nervous stomach) occurs when the colon muscle contracts more frequently than normal. IBS can be triggered by certain foods, medications, and emotional stress. Hemorrhoids are dilated veins in the anal canal, a structural condition. Your anal opening is lined with swollen blood vessels. Chronic excess pressure during bowel movements, persistent diarrhea, or pregnancy can cause them. Hemorrhoids can be internal or external. Digestive problems have many other potential causes. Some are more serious than others. By maintaining a healthy lifestyle, practicing good bowel habits, and getting screened for cancer, you can prevent or minimize many diseases of the colon and rectum.