Epispadias and Exstrophy

Abstract

Exstrophy of the bladder is the commonest member of a group of anomalies of varying severity in which there is a failure of symphysis of the pubic bones, a defect of the abdominal wall, a deficiency of the ventral aspect of the genitourinary tract and sometimes anomalies of the lower bowel. Cloacal exstrophy is the most severe of these, penile epispadias the least, but there are many variants in the combination of musculoskeletal with visceral defects. Marshall and Muecke (1970) have given a well documented account of the whole range and their paper should be consulted for references to the literature before 1962. Muecke (1964) has also made an outstanding contribution to the embryology: working on earlier observations of anomalous embryos with grossly hypertrophied cloacal membranes he has suggested that such a lesion might block the invasion of the membrane by the lateral mesoderm, which would then be diverted caudally leaving the cloacal membrane continuous up to the umbilical stalk and forming the genital tubercle caudal to it as in the classical anatomy of exstrophy. He has then gone on to show experimentally in the chick embryos that the insertion of a small foreign body in the cloacal area could form such a block and produce an exstrophy-like deformity. The corollary of his theory is that all the normal tissues are present, though misplaced and under-developed, and that it should therefore be possible to achieve a surgical reconstruction of a functioning bladder.