Pyelectasis and Fetal Hydronephrosis


During pregnancy urine produced by a developing baby travels from the kidneys, down the ureter and to the bladder. Fetal urine becomes amniotic fluid that supports the baby’s growth and provides room to move.

In some cases, a blockage prevents the urine from flowing normally to the baby's bladder and then into the amniotic fluid. Depending upon the level and degree of blockage, urine may collect in the bladder, ureter and/or kidneys. If the obstruction is mild or partial, an ultrasound may show an accumulation of urine in the renal pelvis, which is the area where the ureter connects to the kidney. This is called pyelectasis.

Pyelectasis will resolve spontaneously more than 90 percent of the time. If the blockage is more severe, your baby may need follow-up care and possibly surgery after delivery.

If the obstruction is more severe, urine may back-up and collect in the kidneys. This is called hydronephrosis. While hydronephrosis can resolve on its own, this problem is more likely to persist after birth, and some babies may eventually require surgery to correct the problem.

In rare instances, the obstruction is so severe that damage to the baby’s kidneys is possible during the pregnancy. For the rare case, fetal surgery during the pregnancy might be offered.

If your baby has been diagnosed with pyelectasis or hydronephrosis during pregnancy, ultrasounds will be performed to monitor your baby’s condition. A consultation with a pediatric urologist may be need so testing and treatment can be planned following your delivery.

We understand that any concerns about your baby's development can be unsettling. But you can rest assured that your Mercy team will at your side with the expert and compassionate care. Our goals is to protect you and the new life you are bringing into the world.

Mercy understands how stressful it can be to know you have a high-risk pregnancy. We’re committed to providing you the best possible care throughout your pregnancy with compassion and loving support, and to your baby after birth. Learn more.

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