What is the management for a pregnant woman at 37 weeks of gestation with elevated Aspartate Aminotransferase (AST) and normal protein levels?

Management of Elevated AST with Normal Protein at 37 Weeks Gestation

At 37 weeks gestation with elevated AST and normal protein levels, immediate delivery should be planned after urgent evaluation to exclude preeclampsia with severe features, HELLP syndrome, acute fatty liver of pregnancy, and intrahepatic cholestasis of pregnancy, as this gestational age represents term pregnancy where delivery is indicated for any hypertensive disorder with severe features. 1, 2, 3

Immediate Assessment Required

Blood Pressure Evaluation

• Measure blood pressure immediately using validated devices to determine if hypertension (≥140/90 mmHg) or severe hypertension (≥160/110 mmHg) is present 1, 2
• If severe hypertension is confirmed, initiate urgent antihypertensive therapy within 15 minutes targeting systolic BP 110-140 mmHg and diastolic BP 85 mmHg 2, 3
• First-line agents include oral nifedipine or IV labetalol 2, 3

Comprehensive Laboratory Panel

The following tests must be obtained immediately to differentiate between pregnancy-specific liver diseases 1:

• Complete blood count with hemoglobin and platelet count to assess for HELLP syndrome (thrombocytopenia <100,000/μL suggests HELLP) 1, 3
• Liver function panel including ALT, lactate dehydrogenase, and bilirubin (bilirubin elevation is abnormal in pregnancy and suggests severe disease) 1
• Coagulation studies including PT, PTT, and fibrinogen to evaluate for acute fatty liver of pregnancy or HELLP with DIC 1, 4
• Serum bile acids (total bile acids) to exclude intrahepatic cholestasis of pregnancy, as elevated levels >40 μmol/L increase risk of adverse fetal outcomes 1
• Serum creatinine and uric acid to assess renal function and disease severity 1
• Urine protein-to-creatinine ratio to quantify proteinuria (≥30 mg/mmol is abnormal), as "normal protein" must be confirmed with objective testing 1, 2, 5
• Blood glucose to exclude hypoglycemia associated with acute fatty liver of pregnancy 1, 4

Clinical Assessment for Severe Features

Evaluate immediately for symptoms indicating severe disease 2, 3, 5:

• Severe persistent headache or visual disturbances (cerebral involvement)
• Epigastric or right upper quadrant pain (hepatic capsule distension or HELLP syndrome)
• Nausea, vomiting, or malaise (may indicate acute fatty liver of pregnancy)
• Shortness of breath or decreased oxygen saturation (pulmonary edema)

Differential Diagnosis at 37 Weeks

Preeclampsia with Severe Features

• AST elevation ≥2 times upper limit of normal (typically >70 U/L) meets criteria for severe features of preeclampsia even without proteinuria 1, 2, 6
• However, elevated liver enzymes alone at this threshold are not independently associated with worse maternal outcomes; the primary concern is the overall clinical picture 6
• If hypertension is present with elevated AST, this constitutes preeclampsia with severe features requiring delivery 1, 2, 3

HELLP Syndrome

• Characterized by hemolysis (elevated LDH, decreased haptoglobin), elevated liver enzymes (AST/ALT), and low platelets (<100,000/μL) 1, 3
• Can occur between 27-37 weeks but may present at term 1
• Maternal mortality rate is 3.4%, making this a critical diagnosis to exclude 3

Acute Fatty Liver of Pregnancy

• Typically occurs in third trimester (29-40 weeks) and rarely postpartum 1
• Clinical presentation includes elevated transaminases, hyperbilirubinemia, hypoglycemia, coagulopathy (elevated PT/PTT, hypofibrinogenemia), and DIC 1, 4
• Hepatic ultrasound or CT may show decreased hepatic density 4
• This is a medical emergency requiring immediate delivery 1, 4

Intrahepatic Cholestasis of Pregnancy

• Typically presents after 30 weeks with pruritus and elevated serum bile acids 1
• AST/ALT may be elevated 2-30 fold, but transaminase levels do not predict adverse outcomes 1
• Total bile acids >100 μmol/L significantly increase stillbirth risk after 35 weeks, warranting delivery at 35-36 weeks 1
• At 37 weeks with confirmed ICP, delivery should be planned regardless of bile acid level 1

Management Algorithm

If Severe Hypertension Present (≥160/110 mmHg)

1. Initiate urgent antihypertensive therapy with IV labetalol (20mg IV bolus, then 40mg after 10 minutes, then 80mg every 10 minutes to maximum 220mg) or oral nifedipine 2, 3
2. Administer magnesium sulfate for seizure prophylaxis (loading dose 4-5g IV over 5 minutes, followed by 1-2g/hour continuous infusion) 2, 3, 5
3. Plan immediate delivery after maternal stabilization, as gestational age ≥37 weeks with preeclampsia with severe features is an absolute indication for delivery 2, 3, 5

If Normotensive with Isolated Elevated AST

1. Obtain comprehensive laboratory evaluation as outlined above to determine etiology 1
2. Perform hepatic ultrasound to exclude biliary obstruction, assess for fatty infiltration, and evaluate hepatic vasculature with Doppler if indicated 1
3. Check viral hepatitis serologies (HAV IgM, HBsAg, HBc IgM, HCV antibody, HEV IgM) if no pregnancy-specific cause identified 1
4. Consider autoimmune hepatitis (ANA, smooth muscle antibody, anti-mitochondrial antibody) if other causes excluded 1

Delivery Timing Considerations

• At 37 weeks gestation, delivery is indicated for any confirmed hypertensive disorder with severe features (including isolated elevated liver enzymes ≥2x upper limit of normal with hypertension) 2, 3, 5
• For intrahepatic cholestasis with bile acids >100 μmol/L, delivery at 35-36 weeks is recommended, so at 37 weeks delivery should proceed 1
• For acute fatty liver of pregnancy, immediate delivery is required regardless of gestational age after maternal stabilization 1, 4
• Induction of labor is preferred over cesarean delivery unless obstetric indications for cesarean exist 3, 5

Critical Monitoring Until Delivery

Maternal Monitoring

• Continuous or every 4-hour blood pressure monitoring 2, 5
• Hourly urine output via Foley catheter with target ≥100 mL/4 hours if magnesium sulfate administered 3
• Deep tendon reflexes assessment before each magnesium dose to monitor for toxicity 3
• Pulse oximetry monitoring (maternal early warning if <95%) 3, 5
• Repeat laboratory tests at least twice weekly or more frequently if clinical deterioration 2, 5

Fetal Monitoring

• Continuous electronic fetal heart rate monitoring to assess fetal well-being 2, 5
• Ultrasound assessment of fetal biometry, amniotic fluid volume, and umbilical artery Doppler if not recently performed 2, 5

Important Caveats and Pitfalls

Do Not Rely on Single Parameters

• Blood pressure level alone does not determine disease severity, as serious organ dysfunction can develop at relatively mild blood pressure elevations 2, 5
• Serum uric acid level and degree of proteinuria should not be used as sole indications for delivery timing 2, 3, 5
• Normal transaminases in early pregnancy do not exclude liver disease, as AST and ALT remain normal throughout normal pregnancy 1, 7, 8

Recognize That Normal Pregnancy Values Differ

• Albumin levels decrease during pregnancy due to hemodilution, so low albumin is expected 1, 7, 8
• Alkaline phosphatase increases significantly in third trimester due to placental production and does not indicate liver disease 1, 7, 8
• Bilirubin, bile acids, and GGT remain normal or decrease in normal pregnancy, so any elevation is pathologic and requires investigation 1, 7, 8

Avoid Contraindicated Medications

• ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated due to severe fetotoxicity causing renal dysgenesis 2, 3
• Diuretics should be avoided as they further reduce plasma volume, which is already compromised in preeclampsia 2
• NSAIDs should not be used for analgesia if delivery occurs, as they worsen renal function in preeclampsia 2
• Short-acting oral nifedipine should be avoided when combined with magnesium sulfate due to risk of uncontrolled hypotension 3

Recognize Rapidly Progressive Conditions

• All cases of preeclampsia should be considered potentially severe, as they can rapidly progress to emergencies 5
• HELLP syndrome can develop rapidly with maternal mortality of 3.4% 3
• Acute fatty liver of pregnancy is potentially fatal and requires immediate delivery after stabilization 1, 4
• Intrahepatic cholestasis with bile acids >100 μmol/L carries markedly increased stillbirth risk after 35 weeks 1

Ensure Appropriate Care Setting

• Management must occur in a hospital with appropriate obstetrical care facilities, maternal intensive care capabilities, and coordination with maternal-fetal medicine specialists, neonatology, and anesthesiology teams 2

In summary, at 37 weeks gestation with elevated AST and reportedly normal protein, the priority is urgent evaluation to determine the underlying cause, immediate treatment of severe hypertension if present, and planning for delivery given that term gestation has been reached and any pregnancy-specific liver disease at this stage warrants delivery after maternal stabilization. 1, 2, 3