Evacuation aids (suppositories or enemas) e.g. glycerine or bisacodyl suppositories may be prescribed. People may have poor resting tone of the anal canal, and consequently may not be able to retain an enema, in which case transanal irrigation (retrograde anal irrigation) may be a better option, as this equipment utilizes an inflatable catheter to prevent loss of the irrigation tip and to provide a water tight seal during irrigation. A volume of lukewarm water is gently pumped into the colon via the anus. People can be taught how to perform this treatment in their own homes, but it does require special equipment. If the irrigation is efficient, stool will not reach the rectum again for up to 48 hours. By regularly emptying the bowel using transanal irrigation, controlled bowel function is often re-established to a high degree in patients with bowel incontinence and/or constipation. This enables control over the time and place of evacuation and development of a consistent bowel routine. However, persistent leaking of residual irrigation fluid during the day may occur and make this option unhelpful, particularly in persons with obstructed defecation syndrome who may have incomplete evacuation of any rectal contents. Consequently, the best time to carry out the irrigation is typically in the evening, allowing any residual liquid to be passed the next morning before leaving the home. Complications such as electrolyte imbalance and perforation are rare. The effect of transanal irrigation varies considerably. Some individuals experience complete control of incontinence, and other report little or no benefit. It has been suggested that if appropriate, people be offered home retrograde anal irrigation.