Pruritus in pregnancy is common (around 20% of pregnancies), but the prevalence of itching due to abnormal liver function tests (LFTs) is less than 1%. In obstetric cholestasis, bile acids accumulate in the blood, causing jaundice and pruritus. There is a 90% recurrence rate in pregnancy, and 35% have a positive family history. Itching typically involves the palms and soles, but can affect the whole body. It is important to rule out other causes of jaundice and pruritus, including hepatitis and gallstones. Screening blood tests include LFTs, bile acids, clotting screen, anti-smooth muscle antibody, anti-mitochondrial antibody and viral serology (hepatitis virus, Epstein-Barr virus and cytomegalovirus). In obstetric cholestasis, transaminases, bile acids, alkaline phosphatase and bilirubin may all be raised.
Treatment includes chlorphenamine (an antihistamine) for pruritus and topical emollients. The lack of bile salts in the gut results in malabsorption of fat-soluble vitamins, including vitamin K, increasing the risk of postpartum haemorrhage and fetal intracranial bleeds. Oral vitamin K supplements are therefore required. Ursodeoxycholic acid, although not licenced for use in pregnancy, has been found to reduce accumulation of bile acids and relieves pruritus. It is important to treat obstetric cholestasis, as there is a risk of premature birth (60%), fetal distress (30%) and intrauterine death by acute anoxia.
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