Acute Fatty Liver of Pregnancy

⚠️ Acute Fatty Liver of Pregnancy (AFLP) is a rare, life-threatening obstetric emergency that typically presents in the third trimester or early post-partum period. It has a variable presentation and can deteriorate rapidly — prompt recognition and delivery are critical to maternal and fetal survival.

🧠 About

• 🩸 AFLP (Acute Fatty Liver of Pregnancy) is an obstetric emergency first described in 1940.
• Characterised by acute hepatic and renal dysfunction late in pregnancy or shortly after delivery.
• Occurs in approximately 1 in 15,000 pregnancies and carries high maternal and fetal mortality if not promptly recognised.
• Pathophysiology involves microvesicular fatty infiltration of hepatocytes due to defective fatty acid metabolism.

🧬 Aetiology

• Typically arises in the third trimester or early post-partum period.
• Results from mitochondrial dysfunction in fatty acid β-oxidation leading to accumulation of fat within hepatocytes.
• Often associated with fetal LCHAD deficiency (long-chain 3-hydroxyacyl-CoA dehydrogenase), a defect in fatty acid oxidation.
• Mothers carrying affected fetuses are at higher risk due to maternal heterozygosity.

⚠️ Risk Factors

• 👩‍🍼 Primigravida
• 👶 Twin pregnancy (higher metabolic load)
• 👦 Male fetus (LCHAD-related association)
• Family history of metabolic disorders

🤒 Clinical Features

• Non-specific symptoms — nausea, vomiting, anorexia, malaise.
• Epigastric or right upper quadrant pain.
• Progressive jaundice and hepatic encephalopathy.
• Can rapidly deteriorate to acute liver failure with hypoglycaemia, coagulopathy, and renal impairment.

🧪 Investigations

• 📊 FBC: Platelet count often normal unless severe DIC develops.
• 🧬 Coagulation: Prolonged PT and APTT, low fibrinogen (note: fibrinogen normally rises in pregnancy).
• 🧫 LFTs: Elevated AST/ALT (usually <1000 IU/L); raised bilirubin and ammonia; hypoglycaemia common.
• 🧪 Exclude viral hepatitis, leptospirosis, and drug-induced liver injury.
• 🧬 Genetic testing: LCHAD mutation testing for mother, baby, and father to confirm metabolic defect.
• 🩻 Ultrasound: May show fatty infiltration of the liver and mild ascites.
• 🧠 Ammonia: Often elevated in encephalopathy.

🧫 Pathology

• Hepatic lobules show microvesicular fatty change (central pallor on microscopy).
• No significant inflammation or necrosis, distinguishing it from viral hepatitis.
• Histology may resemble Reye’s syndrome or valproate-induced liver injury.

🔍 Differentials

• HELLP syndrome (Haemolysis, Elevated Liver Enzymes, Low Platelets) — look for thrombocytopenia.
• Viral hepatitis — higher transaminase levels (>1000 IU/L) and positive serology.
• Drug-induced hepatic failure — paracetamol, anticonvulsants.

⚡ Complications

• Post-partum haemorrhage due to DIC and coagulopathy.
• Acute hepatic failure with jaundice and ascites.
• Renal failure and gastrointestinal bleeding.
• Nephrogenic diabetes insipidus secondary to hepatic dysfunction.
• Maternal encephalopathy and fetal demise if untreated.

🩺 Management

• 🚨 Immediate stabilisation: ABC approach, ICU-level care, and early obstetric consultation.
• 🏥 Definitive management: Prompt delivery of the fetus (often by caesarean section) to halt disease progression.
• 💉 Supportive care: IV fluids, dextrose for hypoglycaemia, broad-spectrum antibiotics, and correction of coagulopathy (FFP, cryoprecipitate, platelets).
• 🧠 Monitor: glucose, coagulation, renal function, electrolytes, and mental status closely.
• 🩸 Manage complications: treat DIC, renal failure, and encephalopathy; dialysis may be required.
• 🫀 Postpartum: liver function typically recovers within days; long-term follow-up essential.
• 🧬 Genetic counselling: advise family regarding LCHAD deficiency testing in neonate and future pregnancies.

📚 References

• Ch’ng CL, Morgan M, Hainsworth I, Kingham JGC. Prospective study of liver dysfunction in pregnancy in Southwest Wales. Gut 2002;51:876–880.
• Nelson DB et al. Acute fatty liver of pregnancy: clinical outcomes and improvement with early recognition and supportive management. Obstet Gynecol 2014;124(3):436–442.
• NICE CKS: Liver Disease in Pregnancy (AFLP Section)

💡 Teaching tip: AFLP is part of the spectrum of pregnancy-related liver disease — think of it alongside HELLP and pre-eclampsia. Always check for hypoglycaemia, low fibrinogen, and LCHAD deficiency. Early recognition and prompt delivery dramatically improve survival.