Because of weak abdominal muscles and reduced sensation, your child may be unaware of the usual feelings of fullness of the bowel and the need to pass a motion and may not be able to voluntarily empty their bowel. In spite of this, most children with Spina Bifida empty their bowels on a daily basis due to pressure from the bowel motion higher up in the bowel and from external abdominal pressure (abdominal massage or lifting legs to change nappies).
Because of the abnormal nerve supply to the bowel caused by Spina Bifida, faeces moves through the bowel fairly slowly. As a result the colon absorbs more than the usual amount of water. The faeces in the colon can become very hard making evacuation difficult and causing constipation. Liquid faeces continues to be delivered to the “top” end of the colon as normal, travels runs around the faeces in the colon and out of the anus giving the impression that the person has diarrhoea and often causing faecal incontinence.
A surgical option available for children with Spina Bifida to achieve adequate bowel control is the MACE procedure (Mitrofanoff for Antegrade Colonic Enema). The goal of the MACE procedure is to provide people with a neurologically abnormal bowel with a good quality of life and achieve social continence.
The operation uses the appendix, or if it has been removed, a similar sized tube fashioned out of bowel. The appendix or tube is implanted into the caecum, the “top of the colon”, to create a valve. The valve allows a catheter to be inserted into the colon, but stops anything coming out in the opposite direction at all other times.
The outside end of the appendix or tube is attached to the skin, either at the umbilicus (belly button) or somewhere else on the abdomen, creating an opening known as a stoma.
About three weeks after the operation the colon is cleaned of any constipated stool using a colonic preparation and running it through the MACE stoma. After this a small catheter can be inserted into the stoma and an enema solution run through whilst sitting on the toilet. This usually takes from 15 to 45 minutes and is done around three times a week. If done regularly there will be no hard faeces in the colon.