Initial observational management of moderate-severe hydronephrosis in infants with reduced differential renal function and non-obstructive drainage parameters
Austin Grayce Hester, MD, Aaron Krill, MD, Eglal Shalaby-Rana, MD, Gil Rushton, MD.
Children's National Medical Center, Washington, DC, USA.
Purpose: Hydronephrosis secondary to ureteropelvic junction (UPJ) obstruction is a common finding in infants with prenatally diagnosed hydronephrosis. Many of these children progress to pyeloplasty based on obstructive drainage parameters and/or renal function compromise. However, little is known regarding the natural history of infants who present with moderate-severe hydronephrosis with reduced differential renal function (DRF) but non-obstructive drainage. We sought to explore our experience with initial observational management of these select patients.
Methods: A retrospective review of our institutional database of all Lasix MAG-3 renal scans obtained between 2000 and 2016 was performed. Inclusion criteria for our study were: isolated antenatally detected unilateral moderate to severe hydronephrosis, first MAG3 scan prior to 18 months of age, DRF < 40% and a half time < 20 minutes. Exclusion criteria were: hydroureter, vesicoureteral reflux, solitary kidney, duplication anomalies. Outcomes of interest were worsening drainage which was defined as a progression of t1/2 to > 20minutes and/or further decline in DRF > 5%.
Results: Of 704 patients with unilateral UPJ obstruction, 91 had DRF <40%, of which 29 (18 boys, 11 girls) met our inclusion criteria and were followed for a mean of 2.8 years (1.4 months - 6.6 years). Mean age at first sonogram was 2.3 months. 2 patients had SFU grade 2, 16 had grade 3, and 9 had grade 4 hydronephrosis (2 unknown). Initial median T1/2 was 10 minutes (3-20 minutes).
22 patients had more than one MAG3 scan. Worsening drainage occurred in 10/22 (45%), median final T1/2 was 45.5 minutes. 8 of these underwent pyeloplasty and 2 were lost to follow up. 4 patients (18%) had progressive decline in DRF (mean 8.3% range 6-10%). Interestingly, 3/4 maintained non-obstructive drainage patterns and stable or improved hydronephrosis and only 1 underwent pyeloplasty. Of the 18 remaining patients, 13 had stable differential renal function, and 5 actually had improvement in DRF. 7 (39%) of these ultimately underwent surgery for worsening drainage parameters. 4/10 (40%) with DRF <35% underwent pyeloplasty versus 5/19 (26%) with DRF 35-40% (p=0.67).
Overall, 7 (24%) patients were discharged from our care, 8 (28%) are under continued observation, 9 (31%) underwent pyeloplasty (1 early, 8 delayed), and 5 (17%) were lost to follow-up. In the ongoing observational group [median follow-up 4.5 years (3.7-6.6 years)], all 8 demonstrated either improved non-obstructive drainage (t1/2 <20 minutes) and/or improvement in hydronephrosis.
Conclusion: Initial observational management of unilateral hydronephrosis with reduced DRF and nonobstructive drainage is recommended as most kidneys maintain nonobstructive drainage and do not demonstrate further decline in differential function. Moreover, even in those whose DRF decreases, the majority remain non-obstructive.
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