Acute Fatty Liver of Pregnancy

Description

• A rare but serious obstetrical diagnosis associated with significant maternal and neonatal morbidity and mortality
• Due to a fetal/placental defect in β-oxidation of fatty acids, toxic metabolites accumulate in the circulation and cause a microvesicular fatty infiltration in maternal hepatocytes.
• This microvesicular fatty infiltrate of the liver leads to significant liver dysfunction and may cause irreversible fulminant liver failure.
• The most reported and studied fetal fatty acid oxidation defect that is linked to acute fatty liver of pregnancy (AFLP) is long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD).
• System(s) affected: hepatorenal, hematologic, central nervous system, gastrointestinal, pulmonary, endocrine (pancreas)
• Synonym(s): obstetric acute yellow atrophy; acute yellow atrophy of the liver

Epidemiology

Incidence
Ranges from 1 in 7,000 to 1 in 16,000 pregnancies (1)[C]

Etiology and Pathophysiology

• Usually presents during the 3rd trimester after 30 weeks’ gestational age but can occur as early as 22 weeks’ gestational age (1)[C]
• Abnormal fetal mitochondrial β-oxidation of fatty acids leads to AFLP in the mother.
• LCHAD is the most frequent fetal diagnosis but AFLP can occur with any fetal fatty acid oxidation defect.
• Women with heterozygous LCHAD defect have a higher risk of developing AFLP if carrying an infant with a homozygous LCHAD defect due to the increased metabolites produces by the fetus and decreased capabilities of the mother to oxidize them.

Genetics
Autosomal recessive mutation in LCHAD

Risk Factors

• Prior pregnancy complicated by AFLP
• Family history of a child with a fatty acid oxidation disease
• Multiple gestation
• Coexisting diagnosis of liver disease
• Male fetus
• Women with heterozygous LCHAD defect

General Prevention

A diet low in long-chain fatty acids and supplemented with medium-chain triglycerides if LCHAD deficiency is present (2)[C]

Commonly Associated Conditions

20–40% of patients who have AFLP have HELLP, and 20% have preeclampsia. Eclampsia, ICP, and hyperemesis gravidarum have a weak association with AFLP (1)[C].