Routine fetal genitourinary tract screening.

To evaluate routine fetal genitourinary tract obstetrical ultrasound screening, and to determine what size renal pelvis is indicative of significant renal disease, we reviewed 4,832 examinations, which had been performed over 2 years, of 3,530 consecutive obstetrical patients. Any fetus that had a renal pelvis greater than 5 mm or a definable cystic area was identified for follow-up. The fetuses of 39 patients (1.1%) who underwent 112 examinations fulfilled these criteria and constitute the basis of this report. A variety of examination criteria were recorded and analyzed in relationship to the follow-up, which ranged from 2-3 days to 21 months. The fetuses of the 39 patients were grouped into three categories: those with renal pelves between 5 and 9 mm in size; those with renal pelves larger than 10 mm; and those with cystic abnormalities. Those with renal pelves larger than 10 mm had either an obstructing lesion or exceptional extrarenal pelves. The clinical and pathologic aspects of these three groups are detailed, discussed, and analyzed. Criteria for significant fetal renal hydronephrosis and aspects of a loculated appearance are given.