THE EARLY PRENATAL SONOGRAPHIC DIAGNOSIS OF RENAL AGENESIS - TECHNIQUES AND POSSIBLE PITFALLS

Out of 13 252 cases in which fetal bilateral echogenic kidneys were de tected by transvaginal sonography between 12 and 18 weeks' gestation, there were nine fetuses where oval hypoechogenic masses were detected in the renal bed. In five fetuses where hypoechogenic masses in the re nal bed were sonographically visualized, postabortal examination was c ompatible with renal agenesis and the hypoechogenic masses proved to b e enlarged adrenals. In three additional cases, unilateral renal agene sis was accompanied by unilateral enlarged adrenals, radiologically co nfirmed postnatally. In one case, a false-positive sonographic diagnos is of Potter syndrome was made because of bilateral hypoechogenic mass es in the renal bed. Postabortal examination detected hypoplastic kidn eys, but of normal histology, in a dyskaryotic fetus with trisomy 22. In four cases of renal agenesis, the amniotic fluid was of normal volu me until the 17th week. In two of the five cases of Potter syndrome, a cystic structure, compatible with the urinary bladder, was detected i n the pelvis at 14 weeks. The diagnostic criteria for renal agenesis i n the early fetus differ from those used in the second half of gestati on.