Prenatal diagnosis of renal agenesis by ultrasonography and maternal pyelography.

Abstract

We recently had an interesting diagnostic problem-the dotection of renal agenesis in utero before 20 weeks gestation. We were able to make a diagnosis using ultrasonography, but at the same time wished to corroborate our findings by means of fetal pyelography. It is with respect to the latter method that we wish to solicit the help of AJR readers. We were asked to study a pregnancy in a patient who had previously had a baby with renal agenesis. Serial ultrasound examinations at 16, 17, and 19 weeks gestation showed oligohydramnios. The fetal urinary bladder could not be seen on any of these studies. We did not spend much time looking for the fetal kidneys, as it has been our experience that these are extremely difficult to see even in the normal fetus. Aminocentesis at 16 weeks yielded a small volume of yellow-orange fluid. All signs pointed to another pregnancy with renal agenesis. On the basis of these findings and one further test described here, therapeutic abortion was recommended and was carried out. Postmortem examination showed that not only were there no kidneys present, but that the ureters and urinary bladder were also absent. We have seen five other patients to date who have had babies with renal agenesis. Ultrasound studies of their subsequent pregnancies showed normal volumes of amniotic fluid and functioning urinary bladders. The case described above was the first of this group of patients in whom any abnormality was detected. We were fairly certain that the pregnancy was abnormal, but as in all such “firsts,” there was the nagging doubt that perhaps we might be wrong and were condemning a normal pregnancy to therapeutic abortion. As a result, we tried one more test before arriving at a final decision, which brings us to