Clinical outcome and management of prenatally diagnosed primary megaureters.

The objective of this study was to evaluate the clinical outcome of infants diagnosed perinatally with primary obstructive megaureter, and to determine which anatomical and physiological indexes best predict such outcome. A total of 67 megaureters thought to be due to primary vesicoureteral junction obstruction was detected in 53 newborns as a result of prenatally diagnosed hydronephrosis or hydroureteronephrosis. These patients were followed nonoperatively using periodic ultrasound and 99mtechnetium-diethylenetriaminepentaacetic acid (Tc-DTPA) renal scans. After a mean followup period of 3.1 years 23 dilated ureters (34%) spontaneously resolved while 33 (49%) persisted. Repair was performed on 11 megaureters (17%) because of breakthrough urinary infections in 3 and deteriorating renal function in 8. Postoperatively, all renal units showed improved drainage on 99mTc-DTPA renal scan, while half of those with decreased renal function regained the lost function. None had further deterioration in renal function. Of the clinical indexes studied ultrasonographic ureteral diameter (less than 6 mm. good, greater than 10 mm. poor prognosis) and drainage on 99mTc-DTPA renal scan correlated best with outcome. We conclude that the majority of primary megaureters detected in the perinatal period can be followed conservatively using periodic ultrasound and 99mTc-DTPA renal scans. Relatively few cases required surgical intervention and those at risk were identifiable by a diameter greater than 10 mm. and poor drainage on 99mTc-DTPA renal scan.