Bladder exstrophy (Ectopia vesicae)
Bladder exstrophy (Ectopia vesicae) is a rare midline congenital anomaly that exists as a part of larger spectrum of the exstrophy-epispadias complex and involves protrusion of the open urinary bladder through a defect in the lower abdominal wall. Its presentation is variable, often including abnormalities of the bony pelvis, pelvic floor, and genitalia. The underlying embryologic mechanism leading to bladder exstrophy is unknown, though it is thought to be in part due to failed reinforcement of the cloacal membrane by underlying mesoderm.
Occurring at a rate between 1 in 10,000 to 1 in 50,000  with a male-to-female ratio of 2.3-4:1.