Seven children with urachal anomalies were encountered in this institution during a 5-year period from 1984 to 1988. Of these 7 cases, 1 was classified as urachal hypogenesis, 1 as urachal cyst, 1 as urachal vesical diverticulum and 4 were classified as urachal umbilical sinus. Ultrasonography seemed to be the most effective tool for diagnosis. All cases except one, in which the urachal cyst resolved spontaneously, were treated by excision. In cases with an umbilical sinus, coring out the opening of sinus was helpful to prevent peritoneal injury. From the aspect of genesis of the urachus, we proposed a new classification for urachal anomalies as follows 1 (1) urachal dysgenesis was classified into (1) a urachal agenesis and (1) b urachal hypogenesis, and (2) urachal remnant was classified into (2) a urachal vesicoumbilical sinus, (2) b urachal umbilical sinus, (2) c urachal cyst and (2) d urachal vesical diverticulum.
