Fetal hydronephrosis – natural history and predictors of postnatal outcome

Abstract

Objectives: The aim of this study was to evaluate the natural history of antenatally detected hydronephrosis and to assess the relationship between the severity of fetal hydronephrosis and postnatal outcome.Materials and methods: During the study period (1992 through 2001), we identified 70 cases of fetal hydronephrosis and reviewed their antenatal and postnatal follow up record retrospectively. The inclusion criteria was renal pelvic antero‐posterior (AP) diameter 4 mm or greater before 33 weeks of gestation and 7 mm or greater at or after 33 weeks of gestation. Sonographically diagnosed fetal simple renal cyst, multicystic dysplastic kidney, or polycystic kidney were excluded.Results: Thirty cases (43.4%) showed hydronephrosis without definite renal pathology after postnatal evaluation. Thirty‐one cases (44.9%) had anatomical abnormalities and the most common renal pathology was ureteropelvic junction obstruction (18 of 31, 58%). Eight cases (11.5%) had regression of hydronephrosis before or at birth. One case was lost in follow up. Twenty cases (28.9%) required surgical intervention, 32 cases (46.3%) needed medical intervention, and 17 cases (24.6%) required neither intervention nor long‐term follow up. All with renal pelvic AP diameter of 15 mm or greater prior to delivery needed either medical or surgical intervention postnatally. With cut off value of 15 mm or greater, the sensitivity and specificity in predicting surgical intervention were 90, and 75%, respectively. The fetus with renal pelvic AP diameter of 15 mm or less prior to delivery had less risk for surgical intervention than 15 mm or greater (Odds ratio 0.046, 95% CI 0.009–0.224). Gestational age at detection of fetal hydronephrosis had no statistical significance in predicting outcome.Conclusion: We concluded that severity of fetal hydronephrosis could affect a postnatal management strategy, either medical or surgical intervention, which is useful in prospective counseling.