Bowel incontinence in MS occurs in two principal situations…(1) an augmented gastrocolic reflex (colonic motility with gastric distention) with postprandial urgency (may or may not sense the colonic movements) and (2) reflex bowel emptying when the rectum becomes full.
Getting the bowel to empty regularly and predictably is the best prevention for reflexive incontinence. Using a pad is important for smaller episodes and confidence. Carrying a change of underclothes/pants is important.
First, parous women may have pelvic floor abnormalities which increase the likelihood of incompetence of the sphincter and urology or gynecology should evaluate.
Second, most medications with anticholinergic actions depress the forcefulness of the reflexes and help to manage urgency.
I don't find a low residue diet helpful. The most helpful is regular BMs. We call this "a bowel regimen." It is similar to what is used for constipation.
History should include the number of BMs. If this is infrequent due to constipation, then augmentation with PEG is used in the dose which regularly will produce a daily DM (1/2-2 doses a day).
To assure regular emptying, each AM they are instructed to have a hot drink for breakfast, preferably coffee, and go to bathroom to have a BM after. They are to use a glycerin suppository for stimulation if it does not occur in a timely fashion. If this is not routinely successful, a Dulcolax suppository can be used.
Those with frequent episodes usually require pharmacotherapy to impair the reflex oxybutynin, hyoscyamine typically. A strong gastrocolic reflex may require using the bathroom on a schedule multiple times a day postprandially.
For those with really aggressive hypermotility and more watery stool situations, cholestyramine is the best strategy, and finding the right dose usually greatly improves the frequency. Loperamide usually is helpful only in the most severe diarrheal cases, but sometimes helps.
GI evaluation is often fruitless. After a colonoscopy patients are usually told there is nothing to do. However, bloody or painful stools, or severe constipation or diarrhea, should have GI review.