What is antenatal hydronephrosis?
Antenatal hydronephrosis means that there is water on the baby’s kidneys in the womb. This means that one or both of the baby’s kidneys are stretched and swollen because they are holding on to urine (wee).
antenatal - before birth.
hydro – water
nephrosis - a problem with the kidneys
It is usually picked up during the mother’s regular antenatal ultrasound scan.
Antenatal hydronephrosis is quite common, affecting about 1 in 100 pregnancies.
Most cases are not serious. The problem often disappears by the time the baby is born, with no long-term effects on the baby or mother.
You may need more scans during the pregnancy to find out whether the antenatal hydronephrosis continues or causes problems. Your baby may also need tests after birth.
How is the urinary system affected?
The urinary system has several distinct parts. After the kidney makes urine, it collects in the renal pelvis before passing into the ureter. In antenatal hydronephrosis, the renal pelvis holds on to urine and it swells up. Sometimes, the ureter that is connected to the kidney also swells up.
In most cases, there are no other problems with the urinary system, and the antenatal hydronephrosis usually resolves (gets better) before birth. These children will probably not have any long-term problems and will not usually need follow-up after birth.
Sometimes, antenatal hydronephrosis is caused by other problems, such as when urine refluxes (passes back) towards the kidney, or an anomaly that blocks the flow of urine.
Rarely, it suggests more serious problems during the pregnancy or after birth.
Babies born with antenatal hydronephrosis will need monitoring and a small number will need treatment, such as surgery.