Anorectal malformations are defects of the anus and the rectum. All kinds of anorectal malformations can and should be repaired. Some types are more likely to cause poor bowel control. The success of bowel control is based on how the sphincter (the ring-like band of muscles that open and close the anus) and the sacrum (the lower part of the spine that forms part of the pelvis) develop.