Progression of hydronephrosis is associated with worsening renal drainage in children with antenatally detected unilateral ureteropelvic junction obstruction
Victor Kucherov, MD1, Briony K. Varda, MD, MPH1, Kenneth Lim, MD2, Eglal Shalby-Rana, MD1, Md Sohel Rana, MBBS, MPH1, Hans G. Pohl, MD1, Aaron J. Krill, MD1.
1Children's National Hospital, Washington, DC, USA, 2MedStar Washington Hospital Center, Washington, DC, USA.
BACKGROUND: Conservative management is often employed for children with unilateral Society for Fetal Urology (SFU) grade 3 hydronephrosis, T1/2 < 40 minutes, and preserved renal differential function (RDF) on diuretic renography (DR), however an optimal imaging strategy for following such patients has not been established. The objective of this study was to determine the association between progression to SFU 4 hydronephrosis and subsequent progression to high-risk drainage (T1/2 ≥ 40 minutes) among children initially managed with observation and interval imaging.
Methods: An institutional database of antenatally detected hydronephrosis was queried. Patients with isolated unilateral SFU grade 3 hydronephrosis at birth, T1/2 < 40 minutes, and normal function (RDF ≥ 45%) were included. Patients with only one sonogram or one DR were excluded. The primary outcome was progression to high-risk drainage (T1/2 ≥ 40 minutes) on DR. The primary exposure was progression to SFU 4 hydronephrosis on sonogram preceding or concurrent with progression to T1/2 ≥ 40 minutes. Covariables included patient sex and kidney laterality. Age at first sonogram and median follow up time were also calculated. Final analysis included descriptive statistics and multivariable logistic regression.
Results: A total of 111 patients were identified for inclusion. Median age at first renal sonogram was 34 days (range 8 - 334). Patients were majority male (76%) with the affected kidney on the left side (also 76%). Median follow up was 3.4 years (range 5 months - 13.5 years). Progression to SFU 4 hydronephrosis occurred in 21% of patients. Progression to T1/2 ≥ 40 minutes also occurred in 21% of patients. Progression to SFU 4 hydronephrosis occurred at a higher rate among those with progression to T1/2 ≥ 40 minutes compared to those whose T1/2 remained < 40 minutes (57% vs 11%, respectively, p < 0.001). On multivariable logistic regression, only progression to SFU 4 hydronephrosis was associated with progression to T1/2 ≥ 40 minutes (OR 12.7, 95% CI 1.9 - 60.9, p < 0.001).
Conclusions: Among children with antenatally detected unilateral SFU grade 3 hydronephrosis and preserved RDF, progression to SFU grade 4 hydronephrosis was associated with progression to high-risk drainage (T1/2 ≥ 40 minutes). These results support the use of ultrasonography as a screening tool to identify potential worsening drainage parameters and thus limit the use of DR for higher risk patients only.
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