Acute onset constipation requires evaluation to rule out bowel obstruction from conditions such as cancer of the colon, diverticulitis with scarring in the colon causing colonic obstruction as well as small bowel obstruction from adhesions, tumors. This usually involves imaging such as computed tomography examination with or without oral contrast. Usually patients with bowel obstruction have significant abdominal pain and/or vomiting.
Chronic constipation is very common. An important cause is underlying medications such as calcium channel blockers, beta-blockers for hypertension. Other medications such as gabapentin, Lyrica a commonly used for chronic back pain can cause sluggish bowel and constipation. Nowadays, many patients who take narcotic pain medications for chronic pain syndromes have constipation because narcotics relax smooth muscle of the gut and because slow gut transit.
From a gastrointestinal standpoint, constipation can occur from colonic inertia wherein the colon muscle is weak and is not able to use to stool from the right side of the colon to the rectum. Another cause that can occur on its own or with colonic inertia is pelvic floor dysfunction typically seen in women. In this condition, the pelvic floor muscles do not relax appropriately to be stool to be evacuated. This occurs frequently in women with a history of multiple previous childbirths with trauma to the pelvic floor muscles during prolonged labor. This literally causes obstructive defecation wherein normal relaxation of the angle between the rectum and anus does not occur. Not infrequently women with this condition perform manual disimpaction of the rectum.
Management of chronic constipation and while stopping the offending medication. Mild cases especially in younger patients may respond to just fiber supplementation. Other agents used to treat chronic constipation include saline laxatives such as polyethylene glycol based laxatives, stimulant laxatives such as Dulcolax, secretagogues like lubiprostone, linaclotide and most recently prokinetics such as prucalopride.
Patients with pelvic floor dysfunction respond to pelvic floor retraining and biofeedback therapy. In extremely rare cases, subtotal colectomy has also been performed although this is very uncommon with availability of effective medical therapy.