Outcome of isolated antenatal hydronephrosis

Objective: To define the clinical outcome in isolated antenatal hydronephrosis (ANH), defined as pelviectasis without vesicoureteral reflux or urinary tract obstruction. Study Design and Patients: We analyzed prospectively gathered data from patients with isolated ANH. Pelviectasis, graded using the anterior-posterior diameter reference criteria, was defined by the status of the more severely affected kidney. Urinary tract obstruction was ruled out by diethylenetriamine pentaacetic acid scan when clinically indicated. Statistical differences were analyzed using the McNemar and chi(2) tests. Results: Isolated ANH was defined in 63 patients. The first postnatal ultrasonogram (mean +/- SD age, 18.4 +/- 17.8 days) revealed resolution of ANH in 16 (25%), mild pelviectasis in 34 (54%), and moderate or severe pelviectasis in 13 (21%). Ultrasonogram at the last follow-up visit (23.3 +/- 14.8 months) in 57 patients demonstrated normal pelvic diameter or mild pelviectasis in 47 (82%) (P=.002). In the 13 patients with moderate or severe neonatal pelviectasis, severity decreased in 11 (85%). Deterioration of any grade of pelviectasis occurred in only 3 (5%) of 57 patients. Renal growth, measured by renal length, was normal in all 57 patients. Conclusion: Isolated ANH resolves or improves in most patients during the first 2 years of life.