Improvement of renal split function in hydronephrosis with less than 10 % function.

PURPOSE: The split function (SF) of hydronephrotic kidneys may dramatically decrease in the presence of severe and persistent obstruction, necessitating surgical correction. The indication for pyeloplasty versus nephrectomy is mainly based on the results of repeated renal ultrasonography (US) and MAG3-diuretic nephrography (DNG) with SF. Nephrectomy is usually recommended if SF is less than 10 %. However, recent studies with long-term follow-up indicate that even with an initial SF of < 10 %, a significant improvement of SF may be seen when pyeloplasty is performed so that nephrectomy may not be justified.

PATIENTS AND METHODS: Case histories of 32 children with pre- or postnatally diagnosed severe hydronephrosis were retrospectively analyzed. Surgical correction was indicated if US revealed progredient hydronephrosis (anteroposterior diameter > 20 mm) and/or DNG demonstrated a loss of SF < 40 % and/or severe obstruction, respectively. Postoperative follow-up examinations included renal US after 3, 6 and 12 months, as well as DNG after 12 months.

RESULTS: Thirty-two children (25 male, 7 female) underwent Anderson-Hynes pyeloplasty (AHP). At the time of operation, the mean age of the patients was 33 months (1 - 156 months). Patients were divided into 3 groups according to the initial SF: group I, 21 patients with SF > 40 %; group II, 7 patients with moderately impaired SF between 10 - 40 %; group III, 4 patients (aged 1 - 137 months) with a SF of < 10 %. In 2 patients, percutaneous nephrostomy (PCN) was performed, followed by AHP. Thirty patients underwent AHP without preceding PCN. In group III, SF increased from < 10 % preoperatively to 21 %, 27 %, 45 %, and 53 % postoperatively, respectively. In all patients, postoperative DNG demonstrated a significant improvement of SF from 41 %, on average, preoperatively (range 0 - 64 %) to 47 %, on average, postoperatively (range 17 - 60 %).

CONCLUSION: Long-term follow-up confirms that the prognosis for renal function is excellent in patients with moderately reduced SF. The significant improvement of SF 12 months after AHP in all patients with a poor SF of less than 10 % supports our approach of performing pyeloplasty in patients even with an initial SF of < 10 %, which is in contrast to common practice.