What is the recommended lab workup for a pregnant woman presenting with chest pain?

Lab Workup for Chest Pain in Pregnancy

The essential lab workup for a pregnant woman with chest pain must include cardiac troponin, complete blood count with platelets, comprehensive metabolic panel, and liver function tests, with additional testing guided by clinical presentation. 1, 2

Immediate Laboratory Testing

Core Laboratory Studies

• Cardiac biomarkers are mandatory when acute coronary syndrome is suspected, as maternal mortality from ACS is 5-10% and can occur at any gestational stage 2
• High-sensitivity cardiac troponin should be obtained in all pregnant patients with acute chest pain, as diagnostic criteria for ACS remain chest pain, ECG changes, and elevated troponin I even during pregnancy 1, 2
• Complete blood count with platelet count is essential to assess for HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) and other hematologic complications 1
• Hemoglobin and fibrinogen levels help evaluate for bleeding disorders and disseminated intravascular coagulation 1

Metabolic and Renal Assessment

• Serum creatinine, eGFR, and electrolytes are required to assess renal function and identify pre-eclampsia-related complications 1
• Lactate dehydrogenase (LDH) and haptoglobin should be measured to evaluate for hemolysis, particularly when HELLP syndrome is suspected 1
• Liver function tests are critical as hepatic tenderness suggests hepatic swelling with risk of rupture in hypertensive emergencies 1

Specialized Testing Based on Clinical Presentation

• NT-proBNP should be obtained if heart failure is suspected, particularly given the risk of peripartum cardiomyopathy which increases with pre-eclampsia 1
• Thyroid function tests are indicated if tachycardia is present, as thyroid dysfunction can mimic cardiac symptoms 2
• sFlt-1/PlGF ratio can predict the short-term absence of pre-eclampsia when the syndrome is clinically suspected, with a ratio of 38 or lower being reassuring 1

Critical Testing to Avoid

D-dimer testing should NOT be used to exclude pulmonary embolism in pregnancy, as it has inadequate sensitivity (73%) and specificity (15%) due to physiologic elevation during pregnancy, with documented false negatives in pregnant women with confirmed PE 3, 2, 4

Urinalysis Components

• Urine albumin-to-creatinine ratio (ACR) is essential for detecting proteinuria associated with pre-eclampsia 1
• Urine microscopy should evaluate for red cells, leukocytes, and casts to assess for renal involvement 1
• Urine drug screen should be obtained when methamphetamine or cocaine use is suspected, as these are risk factors for hypertensive emergencies 1

Additional Considerations for Specific Presentations

When Pulmonary Embolism is Suspected

• Clinical indications include dyspnea, pleuritic chest pain, tachycardia, hypoxemia, cough, and sweating, with tachycardia plus dyspnea occurring in >90% of PE patients 2
• Bilateral compression ultrasound of lower extremities should be performed first if signs/symptoms of DVT are present, as this guides the diagnostic approach 3

When Aortic Dissection is Suspected

• Consider when sudden-onset "ripping" chest pain is described as "worst chest pain of my life" with radiation to upper or lower back 2
• Plasma or urinary fractionated metanephrines may be needed to rule out pheochromocytoma in the differential diagnosis 1

Common Pitfalls to Avoid

• Do not delay necessary testing due to pregnancy concerns, as missing serious maternal conditions poses far greater risk than diagnostic procedures 4
• Do not rely on normal oxygen saturation to exclude serious pathology, as tachycardia with normal oxygen saturation in a pregnant patient with previous PE history should raise suspicion for recurrent PE 3
• Do not assume chest pain is benign even in young pregnant women, as spontaneous coronary artery dissection is more prevalent in pregnant than non-pregnant women 2