Exstrophy of the bladder, or ectopia vesicae, one of the most unfortunate congenital anomalies, occurs once in approximately 40,000 births, the ratio in the male and female being 7 to 1. A portion of the lower anterior abdominal wall and a portion of the anterior bladder wall are completely lacking, so that the posterior wall, with the trigon, presents itself in the suprapubic region, partially everted, as a result of intra-abdominal pressure. In a review of the literature I have been unable to find a report of the occurrence of this anomaly in twins.
The various theories advanced to explain the etiology fall into 3 groups: (1) mechanical, (2) pathologic, and (3) embryologic.
Von Geldern1 states that the mechanical theory may be divided into: “1. The ‘berstungs theorie’ (rupture theory), which considers the cause of exstrophy of the bladder and epispadias as a rupture of the anterior wall of the bladder and the adjacent abdominal wall due to a retention of fluids in the bladder. This retention is believed to be due to constrictions at various points along the genito-urinary tract.” This implies obstruction of the urethra or the vesical neck producing distention of the bladder, which by direct pressure separates the ends of the pubic bones and recti abdominis. Eventually, the anterior wall of the bladder and the abdominal wall contiguous to it rupture, and healing occurs along the edge of the exposed bladder. The obstructive lesion responsible for the distention of the bladder has never been demonstrated. . .