What is Fetal Pyelectasis or Pelviectasis: Diagnosis, Treatment, Association with Down Syndrome

Fetal Pyelectasis or Pelviectasis is a medical condition where there is dilation or enlargement of the central part or pelvis of the kidney of the fetus. This enlargement is due to collection of urine in the kidney where it is not able to pass from the kidney to the bladder resulting in stretching of the kidney in its middle part. This is a comparatively common ultrasound finding in pregnancy and is thrice more commonly seen in male fetuses. It could also be that the fetal kidneys are larger than usual and are actually completely normal. Periodic ultrasounds are done to monitor the kidney pelvis of the fetus. Majority of the times, the Fetal Pyelectasis or Pelviectasis in the fetus resolves on its own without any harmful effects on the baby. The implication of pyelectasis in fetuses is not quite clear; but according to studies, Fetal Pyelectasis or Pelviectasis is thought to be an indication for obstruction; however, in most of the fetuses, pyelectasis resolves spontaneously. In some cases, Fetal Pyelectasis or Pelviectasis appears and disappears multiple times throughout the pregnancy. According to studies, 6 mm of pyelectasis is considered severe enough to warrant investigations.

Pyelectasis is also considered as a “soft marker” for Down syndrome in the fetus. This finding along with other aspects such as abnormal maternal serum screening and age of the mother can be sufficient to get a prenatal diagnostic testing done, such as amniocentesis, to exclude Down syndrome.

Babies who have unresolved or persistent pyelectasis can experience urological problems in the future and may need surgery to fix them.

Fetal Pelviectasis or Pyelectasis is also considered an ultrasound “marker” for Down Syndrome, which means that it increases the risk of the baby having Down syndrome. Down syndrome can develop in fetus in any pregnancy, but the risk increases with maternal age. Fetal Pyelectasis or Pelviectasis, when seen on ultrasound increases the risk for Down syndrome in the baby by about 1.5 times more than the risk associated with mother’s increased age.

Diagnosis of fetal pelviectasis or pyelectasis is done by ultrasound during the pregnancy. Routine ultrasound examination during the 20th week of pregnancy consists of evaluation of the fetal kidneys as part of the prenatal care. Upon the diagnosis of Fetal Pyelectasis or Pelviectasis, close follow-ups are needed; however, treatment is not necessarily needed as frequently Fetal Pyelectasis or Pelviectasis disappears on its own without having any negative impact on the baby. However, infants who have persistent Fetal Pyelectasis or Pelviectasis are at an increased risk for developing urological problems, especially if the urine fails to drain and accumulatees in the kidneys all through the pregnancy. Ultrasound when done after the baby is born can show the babies which have continued fetal pelviectasis or pyelectasis and need treatment. In cases of fetal pelviectasis/pyelectasis where the increase in the size of the kidney is due to obstructed urine flow, then surgery is needed to correct the obstruction after the baby is born. If the ultrasound shows no problem in the baby’s urinary system, then there is nothing to worry about and the baby continues to develop normally.