Diuresis renography in the diagnosis and follow-up of nonobstructive primary megaureter.

Due to the widespread use of obstetrical ultrasonography with concomitant fetal screening, congenital uropathies are usually diagnosed in asymptomatic neonates. The main issue is to distinguish those cases of dilatation which are clearly obstructive and need surgical treatment from those which are within the normal anatomical range. Out of 47 patients with primary megaureter, 23 were nonobstructive and these are the subject of our study. There were 16 males and 7 females. Thirteen were located on the left side, 7 on the right side and 3 were bilateral, adding up to 26 renoureteral units. Prenatal diagnosis was made in 16 cases, the oldest patient diagnosed was 9 years old. All infants were evaluated with ultrasonography, voiding cystourethrography, excretory urography and diuresis renography. The latter has been the most important test inducing us to adopt a conservative attitude. Differential renal function was more than 40% in 24 units and in 2 it was more than 35%. Diuretic renograms were type IIIa (dilated, nonobstructed) in 19 cases and IIIb (dilated, partially obstructed) in 7. There were 2 cases with vesicoureteral reflux in the contralateral system. We performed ultrasonography and diuresis renography during the follow-up. There were 8 cases with type I (normal) renograms and 17 cases with type IIIa. Only one patient developed an obstruction and was operated on. Differential renal function did not deteriorate in any of the cases. Urography was performed in 9 cases during the follow-up. All the patients have remained asymptomatic during the surveillance, except for 2 cases which presented urinary tract infection. BUN, creatinine and other biochemical figures remained within the normal range. The follow-up period of time ranged between 1 and 8 years. We conclude that primary megaureter must be assessed and followed up and that the main test to be used is diuresis renography.