Almost all children with spina bifida have problems with bladder and bowel functions.  Bladder and bowel functions are controlled by the sacral nerves at the bottom section of the spinal cord.  Since most lesions are at or above the sacral level, bladder and bowel functions are almost always affected.

Nerve damage interrupts the messages between the bladder, sphincter muscles, spinal cord and brain.  The bladder and sphincter muscle function is limited and sensation is reduced, but the amount of bladder muscle control and sensation varies greatly depending on the location of the lesion.