Duplications of the lower urinary tract in children.

Seven cases of bladder duplication are described, and compared with 27 cases of urethral duplication. Bladder duplication was collateral while urethral duplication was usually in the sagittal plane. The conditions may coexist when the duplication of the bladder extends caudally to produce a collateral urethral duplication, but in one boy bladder duplication was associated with 4 urethrae in the sagittal plane. In 5 cases the bladders were united; in 2 cases, one bladder was excised. The results were satisfactory in 6 and in one the bladder failed to empty. The basic defects that lead to duplication are unknown. Several features of the conditons suggest that there are different aetiologies in each type. There are similarities with the exstrophy epispadias complex. Even when there are major abnormalities in other systems the general and urological prognosis is good.