Creation of a model of bladder exstrophy in the fetal lamb

Purpose: To our knowledge we describe the first reproducible large animal model to mimic the congenital birth defect of classic bladder exstrophy. Materials and Methods: Eight male and 15 female fetal sheep underwent in utero surgical creation of classic bladder exstrophy. The fetus was then replaced within the amniotic sac and allowed to come to term. A sham procedure was performed on 16 male fetuses. Results: After the creation of bladder exstrophy 53% of the female and 62% of the male fetuses survived to full term and through delivery. Of the male fetuses that underwent sham surgery 62% also survived through delivery. Lambs with exstrophy were born with the bladder wall in continuity with the abdominal wall and exposed to the environment. The sham operated male lambs had a well healed abdominal scar. Conclusions: To our knowledge we have devised the first reproducible large animal model of bladder exstrophy. This model will be useful in studying bladder development and composition in the patient with exstrophy. It may also serve as a useful tool in developing innovative forms of surgical treatment for such patients.