Appropriate follow-up ultrasonography interval after pyeloplasty in children with ureteropelvic junction obstruction

Purpose: Serial ultrasonography (US) is routinely performed after pyeloplasty the setting of pediatric ureteropelvic junction obstruction (UPJO). We ated the adequacy of the follow-up US interval we are currently using, which calls for US at 1, 3, 6, 9, and 12 months following surgery. Materials and Methods: Between January 2002 and August 2005, 102 patients underwent dismembered pyeloplasty for unilateral UPJO. Within this group, we selected 95 patients with high grade hydronephrosis to participate in this study. The degree of hydronephrosis was graded according to the classification issued by the Society for Fetal Urology (SFU). Improvement was defined as at least one grade of reduction. Serial sonograms were performed at 1, 3, 6, 9, and 12 months postoperatively. Results: On follow-up US, 33.7%, 69.5%, 77.9%, 80.0%, and 83.2% of the patients showed improvement in their hydronephrosis at 1, 3, 6, 9, and 12 months, respectively. One patient presented with aggravation at 1 month. However, at 3 months, this patient had returned to the preoperative grade. There was no significant difference between the mean hydronephrosis grades at 6 and 12 months. No patient showed hydronephrosis aggravation at the 12-month follow-up examination. Conclusions: US at 1, 3, and 6 months revealed significant improvements in hydronephrosis. However, no significant change in hydronephrosis occurred beyond 6 months. Therefore, US performed between 6 and 12 months after pyeloplasty may be inefficient, and we propose follow-up US at the following time points: 1 month, 3 to 6 months, 12 months, and then annually.