This is a test performed to evaluate patients with constipation or fecal incontinence. This test measures the pressures of the anal sphincter muscles, the sensation in the rectum, and the neural reflexes that are needed for normal bowel movements. You will be asked to change into a hospital gown. A nurse will explain the procedure to you and answer any questions you may have related to the procedure. The test will be performed by 2 nurses or a nurse and a chaperone will present due to the sensitive nature of the test. You will be asked to lie on your left side. The probe is about the size of a thermometer. The probe has sensors on it to detect pressure. With the probe in place, the nurse will instruct you to squeeze, relax, and push or bear down at various times. The anal sphincter muscle pressures are measured during each of these maneuvers. After this has been done, the probe will be removed. If ordered, a catheter that has an inflatable balloon on the end of it and will be filled with a small amount of water will be inserted into the rectum. You will be asked to expel the balloon as if it were a bowel movement. If you are unable to do so, the balloon will be deflated and carefully removed. Once this has been completed, you may drive yourself home and go about your normal activities. The test takes about 30 minutes to complete. The study is interpreted by gastroenterologists who have expertise in diagnosing and treating gastrointestinal motility disorders. It will take about 2 weeks for results to be completed.
Risks: Anorectal manometry is a safe, low risk procedure and is unlikely to cause pain. Complications are uncommon, however there is a rare risk of perforation (tearing) and/or bleeding. Equipment failure is unlikely but does remain a remote possibility.
lubiprostone, which is FDA approved for OIC
Normal bowel frequency ranges from 3 bowel movements a week to 3 bowel movements daily. There is a poor correlation between the frequency of bowel movements and colon transit.
I reassured her that there were no adverse consequences to having bowel movements 2-3 times a week rather than daily. Perhaps, if she reduced the MiraLAX to 5 caps, ultimately to 2 or 3 caps, she might have less bloating. Because MiraLAX is an osmotic agent, it can cause bloating. Instead of taking the Dulcolax at night, she might want to try taking 1-2 Dulcolax suppositories half an hour after breakfast and waiting until she has extreme urgency before going to the toilet. She asked about psyllium. It is sensible to try this, perhaps beginning at 10 gm in divided doses daily and increasing if tolerated up to 20 gm daily.
We discussed the use of pyridostigmine (Mestinon). This drug is approved for treating myasthenia gravis. It does accelerate the colon transit. However, there are no rigorous trials in patients with idiopathic chronic constipation. We discussed the side effects. If she wants to try this, we will start with 60 mg taken 3 times a day. If necessary, we would increase the dose in 5 days by 1 tablet, and subsequently, again if necessary and tolerated in 60 mg increments until she is taking 120 mg 3 times a day.
We discussed a subtotal colectomy. If she was interested in pursuing this option, we would recommend a colonic motility study. This would provide a more refined assessment of colonic motor function, including contractile responses to a meal and to neostigmine. Following this, we would suggest consultation with a surgeon for consideration of subtotal colectomy. The decision as to whether a subtotal colectomy were advisable would be made jointly by the patient, the surgeon and myself. We might consider a loop ileostomy before a subtotal colectomy. This might inform us as to whether the colon is primarily responsible for symptoms. We discussed the potential risks of a subtotal colectomy but I did not share the estimated risks. I defer to the surgeon to do so. She will let us know if she wishes to pursue this approach.