A diagnosis of autosomal recessive polycystic kidney disease (ARPKD) is usually based on a child's symptoms and the results of an ultrasound scan.

If you have a family history of ARPKD and you're considering having a baby, you may be referred to a genetic counsellor to discuss your options in terms of the tests that can be carried out before and during pregnancy.

A genetic counsellor can also discuss the possibility of pre-implantation genetic diagnosis.

This is where a couple who are both carriers of the ARPKD gene use in vitro fertilisation (IVF) to conceive and the embryos are tested for ARPKD before they're implanted into the womb.

Find out more about genetic testing and genetic counselling

In some cases, it may be possible to detect ARPKD during routine ultrasound scans. The kidneys of a baby with ARPKD may appear unusually large or bright on the scan.

The condition is not usually detected until the second routine scan at around 20 weeks.

If you have a known family history of ARPKD, it may be possible to be more certain about the diagnosis by testing your and your partner's blood to see whether you both carry the faulty gene that causes the condition (PKHD1).

ARPKD can only be passed on to a child if both parents carry the faulty PKHD1 gene.

It's also possible to test the foetus for the genetic mutation, but this involves invasive procedures such as chorionic villus sampling or amniocentesis, which carry a risk of miscarriage.

Tests that can be used to help diagnose ARPKD after birth include:

• a physical examination to look for visible signs of ARPKD, such as a swollen tummy (abdomen)
• blood pressure monitoring
• an ultrasound scan of the kidneys
• a blood test to assess kidney function

Genetic testing for the faulty PKHD1 gene that causes ARPKD may also help support a diagnosis, but it's not routine and is usually only carried out if doctors think there's a possibility that a child's symptoms could be caused by a condition other than ARPKD.