Let's talk about ... obstetric cholestasis
What is obstetric cholestasis?
Obstetric cholestasis (OC) (also known as intrahepatic cholestasis of pregnancy) is a condition in pregnancy characterised by pruritus (itching) without a rash, and abnormal liver function tests, both of which resolve postnatally.
Whilst 23% of women experience some level of itching in pregnancy, in the UK obstetric cholestasis affects 0.7% (about 5,500) of pregnancies. Research indicates that genetic, environmental and hormonal factors all influence its prevalence in populations.
How does it affect pregnancy?
OC is thought to be caused by a build up of bile acids (which are produced by the liver and aid digestion) crossing into the bloodstream and becoming toxic as they reach large quantities.
The bile acids can cause itching for women that can be quite uncomfortable. They can also cross the placenta and are associated with premature labour, fetal distress and, in severe cases, stillbirth. Recent research has found that the risk of stillbirth rises when bile acid levels reach above 100mmol/l; such severe OC affects a small number of pregnancies.
How is it diagnosed?
Although OC usually affects pregnancies from 28 weeks onward, it can start as early as 7 weeks gestation. Most commonly pregnant women will experience itching (itching on the palms of the hands or soles of the feet is particularly suggestive of OC) and inform their midwife who will investigate. Blood tests will be taken for liver function and bile acid levels, abnormal results indicate obstetric cholestasis is likely the cause.
Your midwife will also ask questions regarding other common features of OC; pale stools, dark urine, jaundice (yellowing of the skin), history of liver conditions and family history of OC.
How is it managed?
Your care will be transferred to the obstetric led team and you will have weekly blood tests for liver function and bile acid levels.
There is currently no effective drug treatment for OC. A drug called ursodeoxycholic acid has been used in the past, but a recent study (called PITCHES) found that overall it had no benefit. However, a recent review of over 85 studies found that ursodeoxycholic acid may have clinical benefit when used for the small number of women diagnosed with very severe OC.
For the majority of women antihistamines, methanol lotions and avoiding tight clothing may help to relieve the degree of itching.
Many women with OC are offered an induction at around 37-38 weeks due to the increased risk of stillbirth, although recent research indicates that this could be delayed until 39 weeks for most women.
During your labour it’s recommended that you have continuous fetal monitoring to keep a closer eye on your baby
Postnatally tests should be taken for liver function about 6 - 12 weeks after the birth of your baby to give time for the condition to resolve.
Research
The pathophysiology of obstetric cholestasis is still unclear and research is currently underway to discover more about the condition, and how exactly it affects pregnancy.
A drug called Rifampicin is currently being trialled in Australia and the UK (the TURRIFIC trial) to test it’s efficacy as OC treatment.
Take Home message…if you have itching in pregnancy discuss this with your midwife or GP who will advise if testing for OC is recommended. Early detection of OC will ensure your pregnancy is monitored closely with regular blood tests and obstetric input.
