Management of the primary obstructed megaureter (POM) and indication for operative treatment.

Presented is the diagnostic and therapeutic management of the primary obstructed megaureter (POM). 42 patients presented with 53 ureteral units (UU) of POM (5 females, 37 males, 36 neonates and 6 children aged 3 to 8 years). Of the 53 megaureters 10 UU (19%) were on the right and 27 UU(51 %)were on the left. 8 patients (19%)with 16 UU (30%)showed a bilateral abnormality. In 41% of the patients, hydronephrosis had been discovered by prenatal ultrasound. All patients were evaluated postnatally by ultrasound (US), voiding cysturethrogram (VCUG), intravenous pyelogram (IVP) and diuresis renogram (MAG-3) (DR). Due to the percentage of urinary drainage,the renogram results were classified into different categories:no obstruction, functional obstruction, equivocal and obstruction. A partial renal function was also calculated. Follow-up of the patients ranges between 5 to 48 months (mean: 22.1). All patients underwent serial US and serial DR were obtained in 36 patients. Initially, 9 (17%) UU showed a functional obstruction, 34 (64.2%) an equivocal and 10 (18.8%) an obstructive urinary drainage pattern. 2 kidneys showed a significant decreased partial function of 20, respectively 26%. Surgery was performed in an initial im-paired renal function with an obstructive pattern or in cases with normal function and at least equivocal urinary drainage pattern with no improvement or deterioration of the urinary drainage and/or function in the follow-up. Considering these criteria, 5(9.6%) patients needed surgery. No loss of kidney function has been observed in follow-up. DR is the most valuable diagnostic tool. Criteria interpreting the results are demonstrated in this article.