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Baby—kidney pelvis dilatation

The kidney (or renal) pelvis includes

  • the funnel-like upper part of the ureter which is the tube that drains urine from the kidney to the bladder
  • the calyces—branches of the renal pelvis.

What is renal pelvis dilatation?

Renal pelvis dilatation (or hydronephrosis) is a widening of the renal pelvis and is a common finding on ultrasound scans (USS) performed during pregnancy. Often it is temporary and not associated with any problems in the kidney or ureter. In this situation, there is no risk for your child’s future health.

However, in a small proportion of cases, hydronephrosis can be a sign of problems involving the kidneys, ureters, bladder, or the urethra (tube through which urine leaves the bladder). The two most common conditions are Pelviureteric Junction (PUJ) Obstruction and Vesicourethral Reflex (VUR).

  1. PUJ Obstruction: a partial obstruction at the junction between the renal pelvis and the ureter which can restrict the flow of urine to the bladder. If the obstruction is severe, it can stop the kidney from working normally.
  2. VUR: urine travels down the ureter to the bladder. The junction of the ureter and the bladder normally closes when the bladder contracts in preparation for passing urine to the urethra. If the closure is not complete then urine can travel back up to the kidney. This is called reflux. Reflux can cause dilation of the ureter and renal pelvis.
  3. Other conditions that can cause renal pelvis dilatation are also possible and your doctor will discuss these conditions with you in more detail if required.

What happens once it is discovered?

Usually, the first step is an ultrasound scan of the kidneys (renal USS) after your baby is born. For most babies, the best time to do this is usually five to seven days after birth but it will be done earlier if indicated.

Your doctor will let you know who will follow-up the result of that scan. It will either be at Queensland Children’s Hospital or here at the Mater Hospital. If your baby is well this may occur via a phone call. Further tests may be required and these will be explained to you by your doctor at this time.   

Prophylactic antibiotics

A dose of an antibiotic medicine, given once a day (best given at night), may be recommended depending on the outcome of the renal USS done after birth. This is to reduce the chance of urinary tract infection (UTI) occurring. Mild forms of renal pelvis dilatation have not been shown to benefit from having prophylactic antibiotics.

How to recognise if your child has a UTI

It can be hard to know when your child has a UTI. If your child has a fever it is advisable to see your general practitioner (GP) so your child can be reviewed andtheir urine tested.

Some signs your child may have a UTI include:

  • fever
  • poor feeding
  • being irritable or more tired and sleepy than usual
  • sore stomach.

If your child does have a UTI then further tests may be needed and you can discuss this with your GP.

Appropriate early detection and management of conditions involving the kidney/bladder systems may prevent or reduce future injury or abnormal kidney development for your child.

© 2014 Mater Misericordiae Ltd. ACN 096 708 922

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-430034
Last modified 20/12/2018.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 17/12/2018
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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