Slow-transit constipation: evaluation and treatment.

Slow-transit constipation is characterized by delay in transit of stool through the colon, caused by either myopathy or neuropathy. The severity of constipation is highly variable, but may be severe enough to result in complete cessation of spontaneous bowel motions. Diagnostic tests to assess colonic transit include radiopaque marker or radioisotope studies, and intraluminal tests (colonic and small bowel manometry). Most patients with functional constipation respond to laxatives, but a small proportion are resistant to this treatment. In some patients biofeedback is helpful although the mechanism by which this works is still uncertain. Other patients are resistant to all conservative modes of therapy and require surgical intervention. Extensive clinical and physiological preoperative assessment of patients with slow colonic transit is essential before considering surgery, including an assessment of small bowel motility and identification of coexistent obstructed defecation. The psychological state of the patient should always be taken into account. When surgery is indicated, subtotal colectomy and ileorectal anastomosis is the operation of choice. Segmental colonic resection has been reported in a few patients, but methods of identifying the affected segment need to be developed further. Less invasive and reversible surgical options include laparoscopic ileostomy, antegrade colonic enema and sacral nerve stimulation.