Renal functional outcome in unilateral hydronephrosis in newborn pigs

We followed the course of neonatally induced, partial unilateral ureteral obstruction in pigs and established whether early function or morphological evaluation of the hydronephrotic kidney is predictive of outcome.

In 25 piglets unilateral partial ureteropelvic obstruction was induced 2 days after birth, while 11 underwent sham operation. Only obstructed kidneys with significant dilatation at 4 weeks were included for further study. Renal function was assessed on renography using (99m)technetium-diaminetriaminepentaacetic acid differential uptake. According to the plasma clearance of (99m)technetium-diaminetriaminepentaacetic acid the glomerular filtration rate was determined at ages 4, 12 and 24 weeks. Kidney morphology was studied in parallel by magnetic resonance imaging.

A total of 12 obstructed kidneys with grade 3 or 4 hydronephrosis fulfilled study inclusion criteria. Of 6 kidneys with a functional share of 40% or greater at age 4 weeks 2 deteriorated to less than 40% at 24 weeks, while 4 of 6 with a share of less than 40% at age 4 weeks improved to greater than 40% at 24 weeks. The single kidney glomerular filtration rate at 4 weeks did not correlate with that at 12 or 24 weeks but the rate at 12 weeks correlated with that at 24 weeks (r2 = 0.8140, p <0.001). Neither relative volume of the obstructed kidney nor length of the contralateral nonobstructed kidney correlated with functional share of the obstructed kidney at any age.

Early evaluation of kidney function or volume, or contralateral kidney length did not predict the outcome of neonatally induced unilateral hydronephrosis in pigs.