What is Obstetric Cholestasis?
Cholestasis is the medical term used to describe what happens when bile production by the liver and its flow to the intestine is interrupted for any reason. Some of the most important components of bile are the bile acids which act as detergents making fatty substances dissolve. This allows the body to excrete fatty waste in the bile as well as assisting in the digestion and absorption of fatty substances from the diet. In cholestasis, bile acids and jaundice pigments accumulate in the liver and. then spill into the bloodstream.. Deficiency of fatty nutrients (including vitamin K) may also result from their poor absorption by the intestine.
Obstetric chotestasis is one example of this sort of disorder which occurs during pregnancy and which completely resolves within a week or two after delivery. It usually starts after more than 28 weeks of pregnancy but occasionally starts sooner. It is thought likely that the high levels of the oestrogen hormones that occur in pregnancy cause a reduced flow of bile. Excessive bile therefore accumulates in the blood, causing itching and. in some cases jaundice. Although there is clearly a. relationship between the irritation and the retention of bile salts, the exact nature of this link has not yet been established.
How Common is Obstetric Cholestasis?
It is not yet known how often this condition occurs. However, researchers believe that it may account for a significant proportion of the unexplained stillbirths in the UK today. More research is needed to look at the prevalence of the disease in the UK, which is currently unknown.
What are the Symptoms?
The dominant, and often the only symptom of obstetric cholestasis is generalized itching of the skin. This is known as pruritus. It is not to be confused with ther causes of itching which is a common result of the stretching of the pregnancy progresses.
Other symptoms may include:
- dark urine
- pale stools.
Given that the generalized itching is a classic sign of liver disease, liver function.tests should be carried out. These are performed on a single sample of blood. The liver function tests which are most commonly abnormal in women with obstetric cholestasis are the transaminases, alanine (ALT) and aspartate (AST) aminotransfease alkaline phosphatase (ALP). High.values should prompt further investigations as well as regular monitoring of the baby.
Measurement of serum bile acids is the most sensitive guide to the diagnosis and can be arranged if itching continues to be severe but the ALT, AST and ALP are normal. Deficiency of the fat-soluble vitamin K may cause excessive bleeding in mother and baby if untreated. Vitamin Kdeficiency prolongs the blood’s clotting and can be measured as a prothrombin time (PT).
If the disease remains undetected, obstetric cholestasis may in some instances cause fetal distress, premature delivery, excessive bleeding after delivery and stillbirth.
When the diagnosis has been confirmed, there are several approaches to treatment. Close monitoring under consultant care is essential. This may involve regular scans, cardiographs, blood tests and placental blood flow scans. Whatever treatment is given, early delivery is thought to be vital, with delivery considered desirable by 37/38 weeks. The condition is sometimes treated during the course of pregnancy with the following drugs:
- Ursodeoxycholic acid decreases the level of bile acids and helps bile flow. It has long been used in the treatment of liver disease. However, its use in pregnant women is still under evaluation, although initial results are encouraging.
- Dexamethasone is a steroid and is sometimes prescribed to suppress the production of hormones. This again decreases the level of bile acids and thus helps bile flow. Its use can require further treatment fix the baby after delivery.
- Cholestyramine is what us known as a bile salt chelating resin. This works by binding the bile to itself and the resulting compound being excreted by the body. By removing bile salts it lessens the itching for the mother, although it does not improve the results of the liver function tests. The baby should therefore still be considered at risk.
- Calamine lotions, bicarbonate of soda, anti-histamines and steroid creams are commonly offered to relieve itching. They are of no clinical value to mother or baby and for a woman with obstetric cholestasis, (as opposed to the itching more directly related to skin changes during pregnancy) they may delay more appropriate management or treatment.
- Vitamin K should be given to all mothers whose PT is prolonged prior to delivery.
What About Future Pregnancies?
Obstetric cholestasis tends to recur in future pregnancies. However, this is not always the case. If it does recur it tends to start earlier in the pregnancy and to be more severe. This does not mean that a woman who has suffered the condition in one pregnancy should not contemplate further pregnancies. It simply requires proper management by consultant obstetricians and hepatologists who are familiar with the condition.
Where Can I Get Some Support?
The British Liver Trust has a support group for women who have suffered from obstetric cholestasis, or who suspect that they might have the condition. For further details please contact us.
Download RCOG Obstetric Cholestasis Information Sheet (PDF)