Outcomes of Isolated Antenatal Hydronephrosis at First Year of Life

Objectives: To compare the grade of hydronephrosis between the antenatal and first postnatal ultrasound (US) and their clinical outcomes. Methods: This retrospective study included all cases of isolated hydronephrosis detected by antenatal US from August 2005 to February 2011. Hydronephrosis was classified based on the standard criteria into mild, moderate, or severe. Cases associated with other major congenital anomalies were excluded. All patients were followed-up postnatally and outcomes available were analyzed at one year of age. Results: A total of 105 cases were included out of which 83 (79.0%) were males and 22 (20.9%) were females with a median gestational age of 38 weeks. First postnatal US of 105 cases showed that 20 (19.0%) were free of hydronephrosis, 39 (37.1%) had mild, 29 (27.6%) moderate, and 17 (16.1%) had severe hydronephrosis. Half (50.4%) of hydronephrosis cases improved in their clinical presentation while 13.3% showed deterioration and 36.3% remained the same. Almost half of all cases (52 cases) were diagnosed by US at the end of first year without any effect on renal function. Conclusions: Antenatal and postnatal US are sensitive tools for detecting hydronephrosis as well as for postnatal counseling. Fetal anatomy US is usually done at 18 weeks gestation and if this reveals any evidence of hydronephrosis, the patient is followed according to the severity. Postnatal US is not done routinely for cases where hydronephrosis resolves completely during pregnancy. Although newborns with antenatal hydronephrosis due to secondary causes are at greater risk for renal impairment, surgical intervention reserves renal function.