[Prognostic value of the ultrasound and diuretic renogram in the evolution of ureteropelvic junction obstruction].

INTRODUCTION

The congenital obstruction of the pieloureteral junction (UPJ) is the most frequent cause of hydronephrosis in children. Sometimes, establishing the convenience of a surgical procedure is difficult, mainly if we consider the literature published on the spontaneous resolution of the slight, moderate and even severe hydronephrosis in newborns.

OBJECTIVE

To determine the prognostic value of ultrasound in the evolution of the unilateral hydronephrosis, by assesing the size of the contralateral kidney. To verify if the "supranormal" renal function (SRF) is real or an artefact.

PATIENTS AND METHODS

We have performed a descriptive observational study over a 10 years period (1995-2005). The study included all patients with the only diagnosis of obstructive unilateral hydronephrosis that underwent pieloplasty, and were controlled for 1 year period after the surgical treatment.

RESULTS

Of the 66 patients in the study, 42 were boys (63.6%) and 24 girls (36.4%). After the first diuretic renogram (DR), in 57 of the patients (86.4%) the clearance half-time (T1/2) was over 20 minutes, in 6 cases (9.1%) it was 10-20 minutes and only in 3 cases it was shorter than 10 minutes. A similar differential renal function (FRD) was observed in the moderate and severe hydronephrosis. Supranormal function (FRD > 52%) was detected on DR in 11 patients, predominating in left hidronefrosis, and in more than 50% of the cases this value it did not agree with the renal function measured by dimercapto-succinic acid (DMSA), Pearson's correlation coefficient: 0.19. These kidneys experienced a greater reduction of the postoperative renal function.

CONCLUSIONS

In the unilateral obstructive hydronephrosis, the healthy contralateral kidney experiences hypertrophy detectable by ultrasound, but these ecographic diameters are within the band of individual confidence of the healthy children of reference. The supranormal function exists, but in most cases it is an artefact.