Acute fatty liver of pregnancy is a rare condition that occurs in the third trimester of pregnancy. There is a rapid accumulation of fat within the liver cells (hepatocytes), causing acute hepatitis. There is a high risk of liver failure and mortality, for both the mother and fetus.
Acute fatty liver of pregnancy results from impaired processing of fatty acids in the placenta. This is the result of a genetic condition in the fetus that impairs fatty acid metabolism. The most common cause is long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency in the fetus, which is an autosomal recessive condition. This mode of inheritance means the mother will also have one defective copy of the gene.
Th LCHAD enzyme is important in fatty acid oxidation, breaking down fatty acids to be used as fuel. The fetus and placenta are unable to break down fatty acids. These fatty acids enter the maternal circulation, and accumulate in the liver. The mother’s defective copy of the gene may also contribute to the accumulation of fatty acids. The accumulation of fatty acids in the mother’s liver leads to inflammation and liver failure.
The presentation is with vague symptoms associated with hepatitis :
- General malaise and fatigue
- Nausea and vomiting
- Abdominal pain
- Anorexia (lack of appetite)
Liver function tests will show elevated liver enzymes (ALT and AST).
Other bloods may be deranged, with:
- Raised bilirubin
- Raised WBC count
- Deranged clotting (raised prothrombin time and INR)
- Low platelets
TOM TIP: In your exams, elevated liver enzymes and low platelets should make you think of HELLP syndrome rather than acute fatty liver of pregnancy. HELLP syndrome is much more common, but keep acute fatty liver of pregnancy in mind as a differential.
Acute fatty liver of pregnancy is an obstetric emergency and requires prompt admission and delivery of the baby. Most patients will recover after delivery.
Management also involves treatment of acute liver failure if it occurs, including consideration of liver transplant.
Last updated September 2020