Renal pelvic dilatation

What is the diagnosis?

During your recent ultrasound scan or at your follow-up scan, we have found that your baby has an enlargement of the collecting system (renal pelvis) of one or both of the kidneys. The renal pelvis normally measures less than 7mm at 20 weeks.

What does this mean?

We see this appearance in about in about 1 in 100 (1%) pregnancies at 20 weeks. There is not necessarily a problem with your baby. The enlargement may become less obvious or may increase over the course of pregnancy. It can be a normal variation or can be associated with some degree of blockage in the urinary tract (kidney, ureters, urethra and bladder). In some babies there is a backflow of urine from the bladder into the kidneys (this is called reflux).

What happens next?

You will be given the opportunity to discuss these findings with the fetal medicine midwife.

If the renal pelvis is measuring 7 – 10 mm, we will arrange for you to have a further scan at 32 weeks to repeat the kidney measurement.

If the measurement is greater than 10 mm, or there are any additional findings related to your baby’s urinary tract, you will be seen by a fetal medicine consultant within three working days. An appointment will also be made to discuss your baby’s care after birth with one of our neonatologists (baby doctors).

What is the risk to baby?

This enlargement can make babies more prone to urinary tract infections after birth and in early childhood. To prevent such infections, a low dose antibiotic suspension called Trimethoprim can be given. This will be commenced before you go home with your baby. A discharge prescription will be arranged for your baby before going home. In case there are any additional findings, the detailed management will be discussed with you.

What happens after baby is born?

Your baby will be started on Trimethoprim. We will also arrange for your baby to have a kidney ultrasound scan in the first few weeks of life. You will then be offered an appointment for the Paediatric clinic a month or two after baby’s birth to discuss the scan and whether the antibiotics should be continued.

For further details contact the fetal medicine midwives on 01223- 216185.