How is ICP diagnosed?

Terminology

April 2022

Why have we changed the term ‘liver function test’ (LFT) to ‘liver blood test’?

Until recently, doctors have tended to call the blood test that looks at how well your liver is working a ‘liver function test’. The test checks to see if there is any inflammation or damage to your liver by looking for abnormalities in liver enzymes, such as:

However, the phrase ‘liver function’ is misleading because although the enzymes mentioned above may be abnormal (in general liver disease as well as in intrahepatic cholestasis of pregnancy (ICP)), the liver is still doing the job it needs to do – in other words, it still ‘functions’. In ICP the bile flow may be slower than usual (meaning there is cholestasis, indicated by raised bile acid concentrations), but it is still doing everything it needs to do to keep you alive.

If doctors were worried about liver failure they would perform additional tests to check for this but liver failure is not associated with ICP, which is why you are unlikely to need them.

We think that using the term ‘liver blood test’ is not only more accurate, but will hopefully be less anxiety-provoking, and we anticipate that it will start to be used more frequently over the coming years.

Diagnosis

There is no routine screening for ICP. It is not hard to understand why. One of the challenges is that the condition can present as early as 8 weeks and as late as 40 weeks. This means that women would need repeated screening throughout pregnancy. Also, as it is a relatively uncommon condition of pregnancy (affecting around 5,500 women a year in the UK), the cost implications of testing the whole pregnant population are obvious.

Instead, it is more likely that you will need to mention the itch, either at your antenatal appointment or by phoning the maternity day assessment unit/maternity helpline, and then tests will be performed.

Blood tests required:

Not all hospitals perform the test and some hospitals have to send the blood sample elsewhere for testing. Ideally, you should be able to have the results within 48 hours, but we know that this is not possible for all women at the moment. It’s worth asking your health professional to chase your results if you know that they sometimes take longer to come back.

Bile acids are associated with stillbirth in ICP. Because of this risk, most women with ICP have been giving birth to their babies early. Induction has typically been recommended at around 37–38 weeks of pregnancy, but Ovadia et al. (2019) showed that around 90 per cent of women will be able to delay induction until 39 weeks of pregnancy. However, some women with severe ICP (greater than 100 µmol/L) may need to meet their babies from 34–35 weeks of pregnancy onward. It is essential that bile acids are tested frequently in ICP to ensure that women whose levels may rise above 100 µmol/L are identified, and that the results of these tests are received quickly. The majority of bile acids in this research were non-fasting samples, meaning that the level of risk was based on peak bile acid levels – another reason for not fasting for your bile acid test.