Use of 99mTechnetium-Dimercaptosuccinic Acid to Study Patterns of Renal Damage Associated with Prenatally Detected Vesicoureteral Reflux

Abstract

Static isotope imaging with 99mtechnetium-dimercaptosuccinic acid was performed at a mean age of 34days in 32 children (50 kidneys) whose vesicoureteral reflux had been identified as a result of prenatal ultrasound scanning. Three patterns of isotope uptake were observed: 1) noninfected primary vesicoureteral reflux (15 children, 24 kidneys), 2) noninfected secondary (obstructed) vesicoureteral reflux (9 patients, 11 kidneys) and 3) infected primary reflux (8 infants, 15 kidneys). In 20 pattern 1 kidneys (83%) renal morphology and differential isotope were normal. In the 4 kidneys (17%) that showed evidence of impaired function this took the form of global parenchymal loss, that is small kidneys rather than focal scarring. In pattern 2 the combination of fetal vesicoureteral reflux and obstruction was a potent cause of renal damage with total or near total loss of function in 7 of 9 refluxing units associated with posterior urethral valves and in 2 kidneys with secondary ureteropelvic junction obstruction. Appearances of focal scarring were confined in pattern 3 and were found in 4 kidneys (27%). This overall incidence of detectable renal damage was lower than expected. Even when infection occurs, prenatal diagnosis may lessen the risk of scarring by enabling treatment to be instituted promptly.The findings suggest that uncomplicated primary vesicoureteral reflux is a relatively benign insult to the fetal kidney and that reflux nephropathy found in children presenting clinically is the result of infected vesicoureteral reflux in postnatal life. Any comparison of published studies will prove difficult until there is a more standardized approach to imaging technique and patient selection.