ANTENATAL SONOGRAPHY OF THE KIDNEYS AND U RINARY-TRACT - POSSIBILITIES, USES, DANGERS

Congenital abnormalities of the urinary tract can be detected as early as during the 15th-18th week of gestation. Nevertheless, most abnorma lities are detected between the 28th-30th week of gestation. Antenatal fetal abnormalities vary between physiological dilatation to bilatera l hydronephrosis and polycystic kidney desease. Abnormalities in anten atal fetal ultrasonography are found in 0.5% of all pregnancies, 30-50 % of these abnormalities are related to the urinary tract. Though most of the abnormalities are diagnosed late in pregnancy, irreversible da mage of the kidneys has already taken place by that time and the fetus will not profit from antenatal therapy. On the other hand, a fetus wi th late onset of urinary tract obstruction may profit from antenatal i ntervention or early labor. Repeated ultrasonography is crucial for in itiating further invasive diagnostic procedures, antenatal therapy and for planing the time of labor. There is a great risk of overdiagnosin g and inadequate therapy because too little is known about physiologic al development of the fetal urinary tract in ultrasonography and so ph ysiological and pathological development cannot be differentiated safe ly.