Natural course of isolated mild congenital hydronephrosis: A 2-year prospective study at a single center in Japan

Long-term follow-up of congenital hydronephrosis in a single-center study

OBJECTIVES

Many congenital hydronephroses spontaneously resolve. This study evaluated a long-term follow-up of more than 4 years of patients with congenital hydronephrosis at a single center.

METHODS

In total, 215 patients (286 kidneys) with congenital hydronephrosis were included. Hydronephrosis outcomes (resolution, improvement, and persistence) and time-to-outcome were evaluated.

RESULTS

Fourteen patients underwent early surgical intervention until the age of 2 years. A total of 189 congenital hydronephrosis cases (66%) showed resolution at a median of 16 months (interquartile range: 7-21 months) and 169 (80%) of 210 kidneys with grade I to II hydronephrosis showed resolution at a median of 14 months (interquartile range: 6-23 months). Of 76 kidneys with grade III to IV hydronephrosis, 24 (32%) showed resolution at a median of 29 months (interquartile range: 24-41 months), and 56 (74%) showed improvement to grade II or less at a median of 12 months (interquartile range: 5-23 months). Of the 76 kidneys with grade III to IV hydronephrosis, five required delayed pyeloplasty at a median of 66 months (interquartile range: 42-89 months). One patient was asymptomatic, with a marked worsening of hydronephrosis and decreased renal function 6 years after the resolution of hydronephrosis.

CONCLUSIONS

None of the patients with grade I to II hydronephrosis required surgical treatment, and a shorter follow-up may be sufficient. Grade III to IV severe hydronephrosis should be considered for a longer and more careful follow-up, given the possibility of asymptomatic exacerbation of hydronephrosis.

Appropriate timing of performing abdominal ultrasonography and termination of follow-up observation for antenatal grade 1 or 2 hydronephrosis

Background

Most cases of antenatal the Society of Fetal Urology (SFU) grade 1or 2 hydronephrosis (HN) improve or resolve spontaneously with conservative treatment. However, there is no consensus on the duration of follow-up for cases of grade 1or 2 HN. The aim of this study was to determine the need for continuous follow-up period and new management of children with antenatal grade 1or 2 HN.

Methods

Subjects underwent ultrasonographic assessment for HN according to the SFU classification. We retrospectively evaluated 112 patients with postnatal grade 1 HN and 69 with grade 2 HN using abdominal ultrasonography between January 2010 and December 2017. We examined the change in HN grade on repeat ultrasonography. Kaplan–Meier method was used to show the effect of HN grade on the rate of HN changes.

Results

The mean follow-up duration was 44.9 ± 36.4 months (range 12–274). Initial SFU grade 1 HN disappeared in 47.0% of cases at 12 months, 66.4% at 24 months and 73.2% at 48 months. Initial SFU grade 2 HN showed improvement in grade in 74.7% of cases at 12 months, 88.3% at 24 months and 89.5% at 48 months. However, 14.6% of SFU grade 1 and 2.8% of SFU grade 2 cases increased in grade and of the 17 cases, 16 cases worsened within the first 6 months. No cases with increased grade required pyeloplasty. Initial disappearance and later reappearance of HN occurred in 40.5% of SFU grade 1 and 2 cases. The mean duration of later reappearance of HN was 39.1 ± 36.2 months (range 12–137). No cases showed reappearance of HN after more than 1 year.

Conclusions

Ultrasonography within the first 6 months was necessary for management of children with antenatal grade 1or 2 HN, because some patients showed worsening. After that, it is considered safe to spread the follow-up interval for stable cases. Most cases of grade 1or 2 HN resolved spontaneously, however a few cases reappeared within 1 year. Therefore, ultrasonography after 1 year was necessary in children with HN that spontaneously disappeared. The appropriate time to end the follow-up was considered to have been after 1 year or more has passed since the disappearance was confirmed.