Fetal urinary biochemistry predicts postnatal renal function in children with bilateral obstructive uropathies

Abstract

Objective: To investigate the ability of fetal urinalysis to predict in utero the renal function of children with bilateral uropathy who survive to the second year of life.

Methods: This was a prospective cohort study of 100 consecutive patients with prenatal diagnosis of bilateral uropathy who underwent fetal urine sampling. Fetal urinary concentrations of sodium, chloride, calcium, phosphorus, ammonium, urea, creatinine, glucose, proteins, and beta 2 microglobulin were measured. Prenatal findings were matched with renal function of survivors at 1-2 years. The single end point was serum creatinine, which was considered abnormal when greater than 50 mumol/L (0.56 mg/dL) during the second year of life.

Results: Elevated serum creatinine was found in 17 of 42 children with isolated uropathy who survived more than 1 year. For prediction of elevated serum creatinine during the second year of life, the fetal urinary concentration of beta 2 microglobulin was both specific (0.83) and sensitive (0.80); sodium, chloride, and urea levels were sensitive (0.70 or greater) but lacked specificity (less than 0.65); and fetal urinary glucose, phosphorus, calcium, ammonium, and total proteins were specific (0.70 or greater) but lacked sensitivity (0.65 or less).

Conclusions: Our results provide a new approach to prenatal management of congenital obstructive uropathies by identifying those fetuses at risk for survival with suboptimal renal function. These fetuses might benefit from intrauterine therapy. In contrast, no attempt at prenatal uro-amniotic shunting should be made when a spontaneously good outcome is predicted by fetal urinalysis.