Role of diuretic renal dynamic study in the postnatal management of antenatal hydronephrosis

Forty three renal units with hydronephrosis diagnosed antenatally in 29 children were evaluated postnatally with Diuretic Renal Dynamic Studies (DRDS) using 99mTc-diethylene triamine pentaacetic acid (DTPA). Based on the results of the radionuclide studies 4 renal units were diagnosed as non-obstructive and 7 as obstructive hydronephrosis. The results in the rest of the 31 renal units were equivocal for outflow tract obstruction. All these children were followed up at periodic intervals, approximately between 2-6 months time and evaluated clinically, biochemically and by radionuclide studies (DRDS) up to a period of 2-4 years following institution of conservative or surgical treatment. Four renal units with non-obstructive hydronephrosis and 7 with unequivocally obstructive hydronephrosis were managed by conservative and surgical treatment (pyeloplasty), respectively. Of the thirty-one renal units with equivocal results on DRDS, 10 were treated by pyeloplasty and follow-up studies on them revealed improvement in function and drainage in 8 (80%) while no significant change could be detected in one and further deterioration in renal function was detected in one. The remaining 21 renal units were treated conservatively. Follow-up studies revealed spontaneous improvement leading to complete resolution of hydronephrosis in 13 (62%), no change in 4 (19%) and deterioration in 4 (19%). Overall results of this study revealed that more than 80% of antenatal hydronephrosis showing equivocal pattern on postnatal diuresis renogram either resolved spontaneously or remained stable in the postnatal period over a long period ranging from 2-4 years. Therefore it is suggested that such cases of neonatal hydronephrosis should be managed conservatively initially for a minimum period of one year with periodic evaluation by serial diuresis renal dynamic studied every 2-6 months. Surgical intervention should be contemplated only when there is definite evidence of organic obstruction leading to progressive deterioration of renal function. (author)