What initial laboratory tests should be ordered for a pregnant female?

Initial Laboratory Testing for Pregnant Women

All pregnant women should receive a comprehensive first-trimester laboratory panel including complete blood count, blood type and Rh screen, hepatitis B surface antigen, rubella immunity, syphilis serology, HIV testing, and urinalysis at the first prenatal visit. 1

Universal Screening Tests (All Pregnant Women)

Hematologic Assessment

• Complete blood count (CBC) to identify anemia or other hematologic abnormalities that could impact pregnancy outcomes 2, 1
• Blood type and Rh screen to identify potential Rh incompatibility issues requiring RhoGAM administration 2, 1

Infectious Disease Panel

• Hepatitis B surface antigen (HBsAg) screening is mandatory for all pregnant women at the first prenatal visit to enable postexposure prophylaxis for newborns 3, 1
• HIV antibody testing should be performed as early as possible in pregnancy, as highly active antiretroviral therapy can reduce vertical transmission 3, 1
• Syphilis serology is required universally at the first prenatal visit, with benzathine penicillin G as the treatment of choice 3, 1, 4
• Rubella immunity (IgG) testing to identify seronegative women who require postpartum vaccination 2, 1, 5

Urinalysis

• Urinalysis and microscopy to establish baseline renal function and screen for asymptomatic bacteriuria 3, 2, 1

Risk-Based Screening (High-Risk Women)

Sexually Transmitted Infections

• Chlamydia screening for all women at onset of prenatal care, with repeat testing in third trimester for women younger than 25 years or at increased risk; azithromycin is the treatment of choice 3, 4
• Gonorrhea screening in early pregnancy for women at risk or living in high-prevalence areas, with repeat testing in third trimester if risk continues; treat with ceftriaxone 125 mg IM or cefixime 400 mg orally 3, 4

Hepatitis C Screening

• Anti-HCV antibody testing for women with risk factors (injection drug use, history of sexually transmitted diseases, HIV-positive status) at first prenatal visit 3, 6
• If anti-HCV antibody is positive, obtain quantitative HCV RNA testing to confirm active infection 3
• For confirmed HCV infection, obtain baseline labs including bilirubin, ALT, AST, albumin, platelet count, prothrombin time, and HCV genotype 3
• Screen HCV-positive women for HIV, syphilis, gonorrhea, chlamydia, hepatitis B, and hepatitis A immunity 3

Endocrine Assessment

• Thyroid-stimulating hormone (TSH) should be measured in women with risk factors for thyroid disease or symptoms suggestive of thyroid dysfunction 2, 1
• Fasting blood glucose at the first prenatal visit to screen for pre-existing diabetes, particularly in women with risk factors 2, 1

Special Populations Requiring Expanded Testing

Women with Chronic Hypertension

• Baseline CBC, liver enzymes (AST, ALT, LDH), liver function tests (INR, bilirubin, albumin), serum creatinine, electrolytes, and uric acid to detect superimposed preeclampsia 3, 1
• Urinalysis with protein-to-creatinine ratio or albumin-to-creatinine ratio 3
• Renal ultrasound if serum creatinine or urine testing is abnormal 3

Women with Pre-existing Diabetes

• Hemoglobin A1C, TSH, creatinine, and urinary albumin-to-creatinine ratio 1

Timing and Implementation Considerations

The optimal timing for this comprehensive panel is at the first prenatal visit, ideally in the first trimester. 1 This early screening allows time for interventions such as antiretroviral therapy for HIV, postexposure prophylaxis planning for hepatitis B-positive mothers, and treatment of syphilis or other sexually transmitted infections. 3, 4

Critical Implementation Points

• Women with unknown HBsAg status at delivery should receive urgent screening, and their infants should receive hepatitis B vaccine within 12 hours of birth, followed by hepatitis B immune globulin if the mother tests positive 3
• Rapid HIV testing can provide results in 10-60 minutes for women presenting in labor without prior testing, allowing peripartum interventions to reduce vertical transmission 3
• Effective systems must be established for accurate and timely transfer of maternal test results to labor and delivery and newborn medical records 3

Tests NOT Routinely Recommended

• Lipid panels and liver enzymes are not necessary for healthy women unless specific risk factors are present 2
• Routine serology for genital herpes simplex virus is not recommended; screening is by history and examination for lesions 4
• Universal screening for bacterial vaginosis or trichomoniasis in asymptomatic women is not recommended, as treatment does not improve pregnancy outcomes 4