Background
Most cases of antenatal the Society of Fetal Urology (SFU) grade 1 or 2 hydronephrosis improve or resolve spontaneously with conservative treatment. However, there is no consensus on the duration of follow-up for cases of grade 1 or 2 hydronephrosis. The aim of this study was to determine the need for continuous follow-up period and new management of children with antenatal grade 1 or 2 hydronephrosis.
Methods
Subjects underwent ultrasonographic assessment for hydronephrosis according to the SFU classification. We retrospectively evaluated 112 patients with postnatal grade 1 hydronephrosis and 69 with grade 2 hydronephrosis hydronephrosis using abdominal ultrasonography between January 2010 and December 2017. We examined the change in hydronephrosis grade on repeat ultrasonography.
Results
The mean follow-up duration was 44.9 months. Initial grade 1 hydronephrosis disappeared in 44.8% of cases at 12 months, 66.4% at 24 months and 73.2% at 48 months. Initial grade 2 hydronephrosis showed improvement in grade in 70.0% of cases at 12 months, 88.3% at 24 months and 89.5% at 48 months. However, 13.4% of grade 1 and 2.9% of grade 2 cases increased in grade and 99.3% of these cases worsened within the first 6 months. No cases with increased grade required pyeloplasty. Initial disappearance and later reappearance of hydronephrosis occurred in 13.4% of grade 1 cases and 2.9% of grade 2 cases. The mean duration of later reappearance of hydronephrosis was 6.9 months. No cases showed reappearance of hydronephrosis after more than 1 year.
Conclusions
Ultrasonography within the first 6 months was necessary for management of children with antenatal grade 1 or 2 hydronephrosis, because some patients showed worsening. Most cases of grade 1 or 2 hydronephrosis resolved spontaneously, however a few cases reappeared within 1 year. Therefore, ultrasonography after 1 year was necessary in children with hydronephrosis that spontaneously disappeared. The appropriate time to end the follow-up was considered to have been after one year or more has passed since the disappearance was confirmed.