Prenatal and immediate postnatal ultrasonographic diagnosis of ureterocele.

We report three patients in whom hydronephrosis was diagnosed by ultrasonography in utero. In two fetuses, ureteroceles were detected prenatally and these proved to be the cause of obstruction. In the third, bilateral simple ureteroceles were discovered immediately after birth. In the last patient, failure to see ureteroceles in utero may have been related to the phenomenon of ureterocele eversion and prolapse into the ureter. Ultrasonographers should be aware of this prolapse phenomenon as a potential pitfall for both the in utero and postpartum diagnosis of ureterocele.