Time course of hydronephrotic changes following unilateral pyeloplasty

The temporal pattern of hydronephrotic change following pyeloplasty has not been well defined. To address this issue, 23 years of postpyeloplasty follow-up data from a single surgeon were analyzed.

Records of dismembered pyeloplasty from 1986 to 2004 were retrospectively reviewed. Ultrasound follow-ups were conducted at 3-6-month intervals after surgery for up to 3 years, and were then extended to either annually or biannually until the completion of puberty. Overall outcome of hydronephrosis (HN), timing of initial improvement and normalization were determined. Factors associated with these changes were examined.

Of 215 patients who completed follow-up of at least 5 years, about 80% experienced either normalization or improvement. Once they had shown improvement of HN during follow-up, no recurrence was observed. The median time for recognition of initial improvement and normalization of HN was 8 months and 41 months after surgery, respectively. Multivariate analysis revealed that the presence of immediate postoperative obstruction was a negative factor for initial improvement. Symptomatic presentation and no initial improvement until 6 months after pyeloplasty turned out to be negative factors for normalization.

The results confirm the excellent long-term outcome of pyeloplasty, and highlight the importance of frequent ultrasound until initial improvement of HN, when subsequent ultrasound follow-ups may be safely omitted to focus on follow-up of renal function, proteinuria and hypertension.