Acute Fatty Liver of Pregnancy

Introduction

• Description: Acute fatty liver is a rare complication of pregnancy that results in acute liver failure, often with catastrophic consequences. It is also known as acute fatty metamorphosis or acute yellow atrophy.

• Prevalence: 1/7000–20,000 pregnancies.

• Predominant Age: Reproductive age; typically during the third trimester of pregnancy.

• Genetics: There appears to be a link to a recessively inherited mitochondrial abnormality of fatty acid oxidation, first studied in children with Reye syndrome. The most common defect is a mutation coding for long-chain 3-hydroxyacyl-CoA-dehydrogenase (LCHAD).

Etiology and Pathogenesis

• Causes: Unknown (mimics other forms of fatty liver failure such as that induced by tetracycline in patients with impaired renal function, Reye syndrome, hepatotoxicity with sodium valproate, or salicylate intoxication). It is currently considered that the placenta of a fetus who is LCHAD deficient may produce a toxic metabolite that affects the maternal liver.

• Risk Factors: Unknown. More common in nulliparous women, when a male fetus is present, or when the mother is underweight (body mass index <20), or in multifetal gestation. The risk for recurrence in subsequent pregnancies is low, although it may be higher if the woman has a fetus that is homozygous enzyme deficient.

Signs and Symptoms

• Average gestational age: 37.5 weeks

• Gradual onset of malaise, anorexia, nausea and persistent vomiting (75% of patients), epigastric pain (50%), and progressive jaundice

• Polydipsia/polyuria

• Hypertension, proteinuria, and edema (50%)

• Hypofibrinogenemia, prolonged clotting time, (severe coagulopathy in 55%), hyperbilirubinemia (<10 mg/dL), mild thrombocytopenia, hemolysis, markedly reduced antithrombin III levels, hypoglycemia

• Elevated serum transaminase levels (300–500 U/L), hepatic encephalopathy (60%)

Diagnostic Approach