What routine pre‑marital screening tests should be ordered for a 21‑year‑old woman, including blood type, infectious disease serology, anemia evaluation, genetic carrier testing, and general health assessment?

Pre-marital Health Screening for a 21-Year-Old Woman

For a 21-year-old woman seeking pre-marital screening, you should order a comprehensive panel including: complete blood count, blood type and Rh screen, infectious disease serology (rubella immunity, hepatitis B surface antigen, HIV, syphilis), thyroid function testing, diabetes screening, and ethnicity-based genetic carrier screening. 1, 2, 3

Core Laboratory Testing

Hematologic Assessment

• Complete blood count (CBC) should be performed to identify anemia or other hematologic abnormalities that could impact fertility and pregnancy outcomes 1, 3
• Blood type and Rh screen is essential to identify potential Rh incompatibility issues that would require RhoGAM administration in future pregnancies 1, 3

Infectious Disease Screening Panel

The following infectious disease tests are universally recommended for all women planning pregnancy:

• Rubella immunity (IgG) testing is critical, as rubella infection during pregnancy causes severe congenital defects; seronegative women should be vaccinated before conception and wait one month before attempting pregnancy 1, 3
• Hepatitis B surface antigen (HBsAg) screening is mandatory to enable postexposure prophylaxis for newborns if positive 1, 3
• HIV antibody testing should be offered to all women planning pregnancy, as highly active antiretroviral therapy can reduce vertical transmission to less than 2% 1, 3
• Syphilis serology should be performed universally, with benzathine penicillin G as the treatment of choice if positive 1, 3

Endocrine and Metabolic Assessment

• Thyroid-stimulating hormone (TSH) should be measured to rule out thyroid disorders that significantly affect fertility and pregnancy outcomes; ideally TSH should be <2.5 mIU/L before conception 1, 4
• Diabetes screening (fasting glucose or hemoglobin A1c) is recommended, as uncontrolled diabetes increases risks of congenital anomalies and pregnancy complications 1, 4

Additional Baseline Testing

• Urinalysis should be conducted as part of baseline assessment to establish renal function 1, 3

Risk-Based Screening

Sexually Transmitted Infection Screening

• Chlamydia and gonorrhea screening should be performed in sexually active women, particularly given their impact on fertility and pregnancy outcomes 1

Cervical Cancer Screening

• Cervical cytology (Pap smear) should be up-to-date according to routine screening guidelines (every 2 years for women 21-29 years old), though it is not required specifically for preconception care 4, 1

Genetic Carrier Screening

Ethnicity-Based Recommendations

The approach to genetic carrier screening depends critically on ethnic background:

For Women of Ashkenazi Jewish Ancestry

• Preconception carrier screening should be offered for Tay-Sachs disease, Canavan disease, cystic fibrosis, and familial dysautonomia 4
• Additional conditions to discuss include mucolipidosis IV, Niemann-Pick disease type A, Fanconi anemia type C, Bloom syndrome, and Gaucher disease 4
• If only one partner is of Ashkenazi Jewish ancestry, that partner should be tested first, with testing offered to the other partner only if the first tests positive 4

For All Women Regardless of Ethnicity

• Information about cystic fibrosis carrier screening should be made available to all couples, and it is reasonable to offer CF screening to all couples regardless of race or ethnicity 4
• Caucasian, European, or Ashkenazi Jewish couples should be offered CF screening either sequentially or concurrently 4

For Women of Mediterranean, Asian, or African Ancestry

• Hemoglobinopathy screening (thalassemia, sickle cell disease) should be offered based on ethnic background 4

Sequential vs. Concurrent Partner Testing

When genetic carrier screening is performed:

• Sequential screening is preferred when only one partner has high-risk ancestry—test the high-risk partner first, then test the other partner only if positive 4
• Both partners should be tested concurrently when both have high-risk ancestry 4
• Genetic counseling is mandatory when both partners are found to be carriers of the same condition 4, 5, 6

Important Clinical Considerations and Timing

Optimal Timing

• Testing should ideally occur 3-6 months before attempting conception to allow time for interventions such as rubella vaccination (which requires waiting one month before pregnancy) and optimization of chronic conditions 1

Tests NOT Recommended for Routine Pre-marital Screening

• Lipid panels and liver enzymes are not necessary for healthy women planning pregnancy unless specific risk factors are present 1, 3
• Breast cancer susceptibility gene (BRCA) testing should not be routinely offered unless family history suggests increased risk 4

Follow-up Actions for Positive Results

• Women with positive infectious disease screening require appropriate treatment and counseling before conception 1
• Thyroid dysfunction should be optimized with TSH levels ideally <2.5 mIU/L before conception 4, 1
• Diabetes should be controlled with A1C <6.5% prior to conception to reduce congenital anomalies, preeclampsia, and preterm birth 4, 2

Common Pitfalls to Avoid

• Do not perform HPV DNA testing in women under 30 years of age—it is not recommended for routine screening in this age group 4
• Do not screen for asymptomatic bacteriuria in nonpregnant women—this is not recommended 4
• Do not order expanded carrier screening panels without first considering ethnicity-based targeted screening, as the clinical utility of broad panels remains controversial 7, 8
• Ensure adequate genetic counseling resources are available before ordering carrier screening, as interpretation of results and reproductive decision-making require expert support 4, 8