Acute fatty liver of pregnancy (AFLP) is a rare but life-threatening obstetric condition and is one of the common causes of acute liver failure during pregnancy. AFLP has a low incidence, typically occurring in late pregnancy, and is characterized by pronounced gastrointestinal symptoms, abnormal liver function, and coagulation dysfunction. It presents with abrupt onset, rapid progression, and severe complications, posing a significant risk to maternal and perinatal life. AFLP is a multi-organ disorder with common perinatal complications, including acute kidney injury, disseminated intravascular coagulation (DIC), and multiple organ dysfunction syndrome (MODS).
Etiology
The pathogenesis of AFLP remains unclear. Currently, the prevailing hypothesis is that AFLP is a fetal-origin disease caused by abnormalities in fetal mitochondrial fatty acid oxidation. Studies have suggested that factors such as viral infections, certain medications, genetic predisposition, and nutritional issues might impair fetal mitochondrial fatty acid β-oxidation, leading to the development of AFLP. Additionally, increased levels of estrogen, adrenal corticosteroids, and growth hormone during pregnancy might contribute to fatty acid metabolism disorders, with the accumulation of free fatty acids potentially triggering the condition. The risk of AFLP is higher in primiparas, pregnancies with multiple fetuses, and pregnancies with male fetuses.
Clinical Manifestations
AFLP occurs most frequently in late pregnancy and is characterized by fatigue and persistent gastrointestinal symptoms, such as nausea and vomiting. Other symptoms may include varying degrees of anorexia, lethargy, epigastric pain, and progressive jaundice. As the disease progresses, multiple organ systems can become involved, resulting in hypoglycemia, coagulation disorders, liver and kidney failure, ascites, pulmonary edema, altered consciousness, hepatic encephalopathy, and fetal distress or even stillbirth.
Diagnosis
The diagnosis of AFLP can be established based on symptoms and complementary tests, but other conditions such as severe hepatitis and drug-induced liver injury need to be excluded. Although liver biopsy is the gold standard for diagnosing AFLP, it is an invasive procedure and is rarely performed in clinical practice. The following auxiliary tests are commonly used:
Laboratory Tests
Mild to moderate elevations in transaminase levels are observed, but there is significant elevation of alkaline phosphatase and bilirubin, with a phenomenon of "bilirubin-transaminase dissociation." Hypoglycemia is common and often accompanied by renal dysfunction, significant leukocytosis, prolonged coagulation time, reduced fibrinogen, and thrombocytopenia.
Imaging Studies
Ultrasound may reveal diffuse hepatic parenchymal echogenicity ("bright liver") or ascites. CT imaging of the liver may indicate reduced density and fatty degeneration. However, imaging studies have a certain false-negative rate, and early-stage patients may not show significant findings. The primary utility of imaging is to exclude other liver diseases.
Liver Biopsy
The presence of diffuse microvesicular steatosis of hepatocytes without significant inflammation or necrosis may be observed.
Differential Diagnosis
Viral Hepatitis
Positive serum viral markers, along with higher transaminase levels, are indicative of viral hepatitis.
HELLP Syndrome
A history of preeclampsia is often present, and there is no significant azotemia.
Intrahepatic Cholestasis of Pregnancy (ICP)
ICP is primarily characterized by pruritus and elevated serum bile acids without coagulation dysfunction, renal impairment, or significant gastrointestinal symptoms.
Management
Once an AFLP diagnosis is confirmed, pregnancy should be terminated as soon as possible, with supportive treatment provided to maintain homeostasis.
Obstetric Management
Prompt termination of pregnancy is critical for improving maternal and fetal outcomes. If vaginal delivery is unlikely to be achieved in a short period, cesarean delivery should be performed as soon as possible after improving coagulation function. Vaginal delivery may be considered when labor is inevitable, under conditions of stable maternal status and no signs of fetal distress, with precautions in place to actively prevent postpartum hemorrhage.
Symptomatic and Supportive Management
Stabilizing homeostasis, such as providing energy and protein supplementation, is essential.
Monitoring blood glucose levels is necessary, with hypoglycemia prevention as a priority.
Coagulation abnormalities should be corrected to prevent postpartum hemorrhage.
Prophylactic measures against infection, using antibiotics with low hepatic and renal toxicity, may be administered.
Multidisciplinary collaboration, such as implementing artificial liver support, may be employed to manage complications including hepatic encephalopathy, renal failure, and infections.
Prognosis
AFLP is a fetal-origin disease that tends to resolve on its own postpartum. Early diagnosis and timely termination of pregnancy are associated with favorable outcomes. However, poor outcomes may occur in cases of multi-organ failure. Patients with AFLP generally require several weeks for full recovery postpartum, with no long-term sequelae in most cases.