FETAL PELVI-URETERAL JUNCTION OBSTRUCTION - PREDICTORS OF OUTCOME

Objective To examine the relationship between pre-natal ultrasonograph ic findings typical of pelvi-ureteric junction (PUJ) obstruction and p ost-natal renal function in the affected kidney. Patients and methods This retrospective study comprised 35 infants in whom pre-natal ultras onography had identified a unilateral pattern of dilatation of the ren al pelvis and calices typical of PUJ obstruction, In each case, the pr esence of unilateral hydronephrosis had been confirmed post-natally by ultrasonography, and differential function and drainage evaluated by isotope renography. The results of isotope renography were compared wi th the severity and timing of onset of the fetal hydronephrosis. Resul ts Eleven kidneys (31%) appeared normal in the second trimester and di latation only became apparent during the third trimester. Mean differe ntial function in these kidneys was 48%, However, mean differential fu nction was reduced (mean 38%) in those kidneys noted to be dilated bet ween 16 and 24 weeks gestation. Differential function was loosely corr elated with the severity of dilatation in early onset cases, i.e. the mean differential function was 42% for mild, 37% for moderate and 27% for severe dilatation. A considerable variation in differential functi on values was present in each group except for those with severe dilat ation, which was a significant predictor of poor functional outcome wh en compared with mild and moderate dilatation combined (P<0.01). Concl usion Fetal PUJ obstruction is a heterogenous condition permitting onl y broad predictions of functional outcome. Severe dilatation detected an second trimester imaging predicted significant loss of function. Mi ld and moderate degrees of dilatation were associated with a one in th ree risk of functional impairment in the obstructed kidney.