What Causes Bladder Exstrophy?

Bladder exstrophy is not caused by anything a parent did or didn't do during pregnancy. There is no clear cause for this condition.

It is thought to happen during the 11th week of pregnancy, as the organs develop. Some experts believe that the bladder defect occurs at the times the tissues in the lower wall of the belly or abdomen develop. At the same time, the developing muscles and pelvic bones are affected too.

A temporary tissue called the cloacal membrane covers the lower belly wall and is replaced by maturing and developing abdominal muscles. If the cloacal membrane bursts before the abdominal muscles fully form, this may result in an "exstrophied" bladder. Another tissue called the urorectal septum helps to separate the developing bladder from the bowels or intestines.

Whether the child is born with epispadias, classic bladder exstrophy, or cloacal exstrophy depends on when the cloacal membrane bursts and if the bladder and intestines are separated by the urorectal septum.

  • An epispadias is a rare birth defect of the penis, where the urethra ends in an opening on the top side of the penis. For girls, the urethra develops too far up front.
  • Cloacal exstrophy (EC) is a severe birth defect where the abdominal organs (the bladder and intestines) are exposed. The penis or vagina is split, and the anus may be sealed.

Mostly, bladder exstrophy occurs as the only birth defect. Spinal cord problems can also occur but are more common with cloacal exstrophy.