This , however , is as rare as conjoined twins , and only happens to one out of every 100,000 live births . It is usually very bad for the kidney and bladder , and only about four survivors were known to be alive as of July 2003 . This condition is about as rare as conjoined twins , affecting one out of every 100,000 live births and is usually fatal within a day or two of birth because of kidney and bladder complications .