Renal Pelvis Dilation

Important information for patients Fetal Medicine Unit

If you have any questions or concerns, please contact

the Fetal Medicine Unit on 01270 273775 (Monday to Friday, 9.00am - 5.00pm).

This leaflet is available in audio, Braille, large print and other languages. To request a copy, please telephone 01270 273775.

Revised and reprinted July 2021 Review July 2024 Ref: WC/MS/0340721 www.mchft.nhs.uk We care because you matter

Your baby has been found to have more fluid in its kidneys than What does this mean for my pregnancy? normal. This leaflet will explain what this means for your baby. First of Due to renal pelvis dilation: all, it is important for you to understand how kidneys work.

• Your baby will not have to be born early. How does the renal system work? The kidneys work to filter out water and waste products from the body

• There is no increased rate of miscarriage or preterm delivery. and dispose of it as urine. This urine makes up the amniotic fluid that surrounds and protects baby, whilst baby is in the womb. • Your baby’s growth will not be affected.

The outer part of the kidney (renal cortex) creates the urine, whilst What will happen once my baby is born? the inner part (renal pelvis) collects it and drains it into the ureter.

Your baby will be examined by a Paediatrician who will arrange any Urine flows from the renal pelvis down the tube called the ureter into follow-up that is needed. the urinary bladder. The urine is stored in the bladder and then

passes through the urethra. There are valves at the entrance to and • Your baby will need to have passed urine before you go home. exit from the bladder, to stop urine leaking all the time and to stop it flooding up to the kidney (see picture on page 3). • An ultrasound scan will be arranged for your baby after birth to assess the renal pelvis dilation. Your baby can go home with How do we check the renal system during pregnancy? you and come back to hospital for this scan. During your 18-20+6 week scan the sonographer will look at the appearance of your baby’s kidneys and measure the renal pelvis • The Paediatrician may feel it is necessary to put your baby on from ‘front to back’. The normal measurement of the renal pelvis is antibiotics to prevent any urinary tract infections (UTI’s). up to 7mm before 28 weeks and up to 10mm after 28 weeks. If the • If this scan is normal then your baby will be rescanned a final measurement is more than this, it is called renal pelvis dilatation; this

time at about 6 weeks old. This scan will be performed at the is sometimes abbreviated in your notes as renal pelvis dilation. hospital. If this later scan is normal, then your baby will not need to be seen again. How common is it? Renal pelvis dilation is one of the most common findings seen on • If the renal pelvis dilation is more than 10mm on the first scan, ultrasound at the 18+0 to 20+6 weeks anomaly scan and occurs in

then your baby will be seen by a Paediatric Urologist (baby approximately 1 in 100 (1%) babies in the UK.

doctor specialising in kidneys) and they will organise further investigations. These investigations will be organised by Alder Why does it happen?

Hey Children’s Hospital. In a small number of cases, 3 in 100 In most cases, there is no underlying problem and it may be a (3%), your baby may need an operation at some time during temporary finding when the baby’s bladder is full. The most common childhood. cause of renal pelvis dilation is pelvi-ureteric junction obstruction or blockage (see picture on page 3). This usually only affects one side and if mild has no long term effects. 5 2 An obstruction can also occur where the ureter narrows as it joins the bladder. We call this vesico-ureteric junction obstruction (see picture Left kidney Right kidney opposite). This is responsible for 1 in100 (1%) of renal pelvis dilation. In most cases it is difficult to tell the difference between pelvi-ureteric

Renal pelvis junction and vesico-ureteric junction blockage before birth.

How will this affect my baby? Of all babies with confirmed renal pelvis dilation, approximately 8 in Pelvi-ureteric 10 (80%) will have mild renal pelvis dilation which will almost always junction (PUJ) return to normal before or after birth.

Of those with more severe renal pelvis dilation, a third will get better on their own, half will stay the same and the rest will get worse during the pregnancy. During pregnancy there is no need for any treatment Renal cortex before your baby is born.

If you have had screening for Down’s Syndrome the diagnosis of Left ureter renal pelvis dilation will not alter the risk of your baby having Down’s Right ureter Syndrome.

If no other problems have been identified during your scan, renal pelvis dilation has little to no association with any chromosomal abnormalities.

What will happen next? You will be given an appointment for a follow-up scan in Antenatal Vesico- Clinic or the Fetal Medicine Unit. The renal pelvis dilation may have ureteric resolved by your next scan. junction (PUJ) If the renal pelvic dilation continues, you will have a repeat scan by a Bladder specialist in the Fetal Medicine Unit.

Site of During pregnancy there is no need for any treatment before your posterior baby is born. urethral valves Urethra A plan from a Paediatrician will be put in place which will be discussed with you explaining what will happen after your baby is born. 3 4