Hydronephrosis in babies — a basic overview

Hydronephrosis in babies (hydronephrosis surgery)


Hydronephrosis (ˈhī-drō-ni-ˈfrō-səs), or swelling of the kidneys, in babies is a condition that affects approximately one in 100 infants.1 It occurs when urine overfills or backs up into the kidneys, which causes them to swell. This condition may correct itself, however, in severe cases it may require hydronephrosis surgery.

Hydronephrosis in babies has several causes (see below), and most of them do not result in harm to the kidneys. However, in some instances, hydronephrosis is associated with kidneys that are functioning poorly.

Hydronephrosis can affect one or both kidneys. Fortunately, this condition resolves itself in about half of all cases.2


A blockage in some part of the urinary tract can cause hydronephrosis in babies. Another cause can be vesicoureteral reflux (VUR) which is an abnormal backflow of urine from the bladder to the kidneys.1

In the absence of a blockage or VUR, hydronephrosis in babies may be caused by an abnormal development or formation of the kidney.

In addition, there are some instances when hydronephrosis has a genetic cause.


Hydronephrosis in babies is typically characterised by either no or minimal symptoms. The most fundamental approach in diagnosing and managing hydronephrosis is to perform routine ultrasound testing that monitors kidney growth and function during pregnancy, infancy, and childhood.

If hydronephrosis is found during pregnancy, it will usually resolve itself with no damage to the kidneys after your child is born.

Hydronephrosis surgery

It is only in severe cases that hydronephrosis in babies requires surgery. When this is the case, the goal of the operation is to reduce pressure and swelling in the kidney by restoring the free flow of urine.


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