What are the causes of ICP?
We do not yet know what causes the restriction of the flow of bile from the liver in ICP. Evidence suggests that it is caused by a combination of hormonal, genetic and environmental factors.
All hormones are metabolised (broken down) in the liver. One theory is that the liver cannot cope with the high levels of hormones during pregnancy (oestrogen and progesterone). This affects the liver’s ability to remove bile acids efficiently and causes a build up of bile acids in the blood. This is supported by observations that:
- ICP is more common in twin and triplet pregnancies, which are associated with higher levels of hormones.
- ICP has been triggered in women taking high-dose oral contraceptives (which contain forms of oestrogen and progesterone) and also in women being treated with progesterone.
ICP also has a genetic cause. This means it has been linked to genetic changes making some women more susceptible to the disease. This can also explain cases where ICP occurs within families and why it is more common in some ethnic groups.
Although ICP affects one in 140 (0.7%) pregnancies in the UK overall, it is more common in women of Indian or Pakistani origin, affecting around one in 70 to 80 (1.2 – 1.5%) pregnancies. In other places, such as South America and Scandinavia, the number of
women affected is higher still.
However these genetic changes do not explain all the causes of the disorder and other factors such as diet and hormones may play a part. Further research is being carried out to investigate these areas.
Some characteristics of ICP suggest that environmental factors may also have a role.
- ICP does not always recur in following pregnancies.
- ICP can be more common in certain seasons (in the winter months in Chile and Scandinavia).
- Cases of ICP have decreased in countries where nutrition has improved.
Women with hepatitis C more commonly develop ICP than those who do not have the virus.
ICP: Symptoms and Diagnosis
Itching is often the only symptom of ICP. The itching typically begins on the arms, legs, hands and soles of the feet. It may also occur on other parts of the body such as the face, back and breasts. It is usually worse at night, leading to sleeplessness and exhaustion.
Some women scratch themselves so frantically that they make themselves bleed. A few lose their appetite and feel generally unwell. A number of women (thought to be around one in ten) will develop jaundice in pregnancy. However, most women with ICP do not have jaundice.
Itching is not uncommon in normal pregnancy. However, some women may not be aware that they have ICP because they are told that itching is normal in pregnancy. This can be misleading.
Your doctor should ask about your medical and family history to aid diagnosis. If close female family members have been affected by ICP then you may be at increased risk.
It is also important to exclude all other possible causes of your itching, such as allergies or eczema (but it is possible to have a skin condition and ICP). Other signs such as pale stools or dark urine may indicate a problem with your liver, including ICP.
Your doctor can diagnose ICP from blood tests called liver blood tests and a serum bile salt test. Liver blood tests are performed to gain an idea of how your liver is functioning. A number of separate properties of your blood will be examined. Your doctor should use pregnancy-specific reference ranges to interpret your blood test results.
In ICP, doctors will be looking for abnormal levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Sometimes levels of another enzyme, gamma-glutamyl transferase (GGT), will also be raised. The most specific test involves measuring serum bile salts.
In most women with ICP, both ALT and bile salt levels will be raised, but just one may be raised at the first test. If the tests are within normal limits and you carry on itching, it is important that the tests are repeated. Unfortunately the serum bile salt test is not available in all hospitals. Your doctor may need to send a sample to another hospital for diagnosis.
Women with hepatitis C are at increased risk of developing ICP during pregnancy. A small number of women with ICP may therefore have undiagnosed hepatitis C. If your test results do show that you have viral hepatitis, or another liver condition, you will then be able to be referred to a specialist in liver disease (hepatologist) and receive treatment.
ICP is only completely confirmed when symptoms disappear and liver tests go back to normal after delivery.
There is no cure for ICP. Doctors will monitor your condition, treat symptoms and may advise delivering your baby early.
Topical creams such as calamine lotion and aqueous cream with menthol, are safe and may provide some temporary relief from itching for some women.
A number of medications may be used in your treatment. As yet, a specific medication to manage ICP is not available, although clinical studies are in progress. Medication is currently aimed at reducing the build-up of bile salts in your blood, to relieve the itching and to protect your baby.