Liver function is not impaired in pregnancy. Any liver disease from whatever cause can occur incidentally and coincide with pregnancy. For example, viral hepatitis accounts for 40% of all cases of jaundice during pregnancy. Pregnancy does not necessarily exacerbate established liver disease, but it is uncommon for women with advanced liver disease to conceive.
The following changes take place:
Plasma and blood volumes increase during pregnancy but the hepatic blood flow remains constant. 2 The proportion of cardiac output delivered to the liver therefore falls from 35% to 29% in late pregnancy; drug metabolism can thus be affected.
3 The size of the liver remains constant.
4 Liver biochemistry remains unchanged apart from a rise in serum alkaline phosphatase from the placenta (up to three to four times) and a decrease in total protein and y-globulins.
5 Triglycerides and cholesterol levels rise, and caeruloplasmin, transferrin, a,-AT and fibrinogen levels are elevated due to increased hepatic synthesis. There are a number ofliver diseases that complicate pregnancy.
Pathological vomiting during pregnancy can be associated with liver dysfunction and jaundice. This is never severe and resolves when vomiting subsides. Liver histology (biopsy seldom indicated) shows cholestasis.
Pre-eclampsia and eclampsia
Pre-eclampsia complicates 10% of pregnancies of which 10% have deranged liver biochemistry (usually minor). In more severe cases disseminated intravascular coagulation (DIC) occurs. The HELLP syndrome refers to a combination of haemolysis, elevated liver enzymes and a low platelet count and can occur in association with preeclampsia. If eclampsia supervenes, there is epigastric pain, nausea and vomiting with severe hepatic damage; fetal and maternal death can occur. Liver histology shows fibrin deposition, ischaemic necrosis and periportal haem orrhage thought to result from vasospasm. Hepatic haem orrhage and rupture are very rare. Urgent delivery of the fetus is required along with laparotomy to repair damage.
Intrahepatic cholestasis of pregnancy
This condition of unknown aetiology presents usually with pruritus in the third trimester. It has a familial tendency and there is a higher prevalence in Scandinavia, Chile and Bolivia. Jaundice is not a prerequisite for diagnosis and the AST may be normal or rise three to four times. Liver biopsy is not indicated but would show centrilobular cholestasis. Treatment is symptomatic with cholestyramine in high doses (up to 24 g daily). Prognosis is excellent and the condition resolves after delivery. Recurrent cholestasis may occur during subsequent pregnancies or with the ingestion of oestrogen containing oral contraceptive pills.
Acute fatty liver of pregnancy
This is a rare, serious condition of unknown aetiology. It presents in the last trimester with symptoms of fulminant hepatitis, i.e. jaundice, vomiting, abdominal pain, possibly haematemesis and coma. Laboratory investigations show hepatocellular damage, hyperuricaemia and possible DIC. Liver biopsy is contraindicated but histology shows fine droplets of fat (microvesicles) in the liver cells with little necrosis. CT scanning is non-invasive and shows a low density of the liver due to the high fat content.
Immediate delivery of the child may save both baby and mother. Early diagnosis and treatment has reduced the mortality to less than 20%. Treatment is as for acute liver failure.