OBJECTIVE: Routine maternal ultrasonography has revealed a very high incidence of fetal hydronephrosis. However, there is little data available, in Korea, on the natural progress of prenatal hydronephrosis. Therefore, to help in the management of patients, the antenatal course and neonatal follow-up data of isolated fetal hydronephrosis were analyzed. METHODS: Prenatal diagnosis, etiologies, clinical characteristics, and outcome were studied retrospectively in 77 cases of unilateral and bilateral prenatal hydronephrosis from January 2000 to March 2004. Cases were classified as mild (7 mm > or =, < or = 10 mm), moderate (10 mm >, < or = 15 mm), and, severe (15 mm >) prenatal hydronephrosis as depending on the renal pelvis anteroposterior diameter. Fisher's exact test and Chi-square test were used for statistical analysis. RESULTS: The etiologies of prenatal hydronephrosis were ureteropelvic junction obstruction 45 (58.4%), vesicoureteral reflux 2 (2.6%), ureterocele 1 (1.3%), and urethra obstruction 1 (1.3%). At delivery, 18 cases were normal kidneys, and during the follow-up periods, 10 cases resolved spontaneously. Mild, moderate, and severe hydronephrosis were present in 30 (38.9%), 38 (49.4%), and 9 (11.7%) respectively. Operations were performed in 2/38 (5.3%) of moderate cases, and 7/9 (77.8%) of severe cases. CONCLUSION: Most of prenatal hydronephrosis diagnosed by ultrasonography disappeared postnatally and the needs for postnatal operations were rare. It is suggested that hydronephrosis in the fetus or neonate dose not necessarily imply the presence of an obstructive uropathy or a significant functional abnormality and the reassurance of parents and follow up evaluation of the neonate during perinatal period may be needed.
Fetus ; Follow-Up Studies ; Humans ; Hydronephrosis* ; Incidence ; Infant, Newborn ; Kidney ; Kidney Pelvis ; Korea ; Parents ; Prenatal Diagnosis ; Retrospective Studies ; Ultrasonography ; Ultrasonography, Prenatal ; Ureterocele ; Urethra ; Vesico-Ureteral Reflux