Recommended Blood Work for First Antenatal Visit
The essential blood work for the first antenatal visit should include complete blood count, blood typing and antibody screening, hepatitis B surface antigen testing, HIV testing, rubella immunity testing, syphilis screening, and blood glucose screening. 1, 2
Core Laboratory Tests
- Complete blood count (CBC) to assess for anemia, which is common during pregnancy, with hemoglobin determination being particularly important 1, 3
- Blood typing and antibody screening to identify potential blood incompatibilities and determine Rh status 1, 2
- Hepatitis B surface antigen (HBsAg) screening to recognize and reduce the risk of mother-to-child transmission 1, 2
- HIV testing for early identification and management to prevent vertical transmission 2
- Rubella immunity testing to identify susceptible women who will need vaccination postpartum 2
- Syphilis screening to detect and treat infection early 2
- Urinalysis for protein and glucose to screen for renal disease and diabetes 1, 4
Metabolic and Endocrine Screening
- Fasting blood glucose should be measured at the first prenatal visit to screen for pre-existing diabetes 1, 2
- All pregnant women with risk factors for diabetes should be tested for undiagnosed prediabetes and diabetes at the first prenatal visit using standard diagnostic criteria 5
- Women with clinical characteristics consistent with high risk of gestational diabetes (marked obesity, personal history of GDM, glycosuria, strong family history of diabetes) should undergo glucose testing as soon as feasible 5
- Thyroid-stimulating hormone (TSH) testing should be considered, particularly for women with pre-existing diabetes or thyroid disorders 1, 2
Additional Recommended Tests
- Hepatitis C virus (HCV) screening, especially for women with risk factors 2
- Cervical cultures and Pap smear should be obtained at the initial visit 1, 2
- Urine culture and dipstick for leucocyte esterase and nitrite to reduce the risk of pyelonephritis 3
Special Considerations
Women with Chronic Hypertension
- More comprehensive baseline laboratory assessment including liver enzymes, renal function, and uric acid levels 1, 2
- These tests provide a baseline reference for detecting superimposed preeclampsia 1
Women with Pre-existing Diabetes
- Additional testing should include A1C, thyroid-stimulating hormone, creatinine, and urinary albumin-to-creatinine ratio 1
- Comprehensive eye examination to assess for diabetic retinopathy 1
Common Pitfalls to Avoid
- Failing to screen for hepatitis B in the first trimester, which is crucial for preventing mother-to-child transmission 1, 2
- Delaying glucose screening in high-risk women, which should be performed as early as possible in pregnancy 1, 2
- Not providing adequate counseling regarding screening options for aneuploidy and the benefits, risks, and limitations of different tests 2
- Overlooking the importance of baseline laboratory tests in women with chronic medical conditions 1, 2
- Not following up on abnormal results promptly 2
Aneuploidy Screening Options
- First trimester screening (11-14 weeks) includes nuchal translucency measurement via ultrasound, pregnancy-associated plasma protein A (PAPP-A), and human chorionic gonadotropin (hCG) or free beta-hCG 2
- Women should be informed that first trimester screening has a detection rate of approximately 70% for Down syndrome with a 5% false-positive rate 2
- All women should have the option of invasive diagnostic testing (CVS or amniocentesis) regardless of maternal age 2
Second Trimester Follow-up Testing
- Maternal serum alpha-fetoprotein (MSAFP) screening for detection of open neural tube defects and anencephaly should be offered between 16-18 weeks gestation 1, 2
- Multiple marker screening should be offered to women who did not have first trimester screening 2
- Glucose challenge test for gestational diabetes screening at 24-28 weeks for average-risk women 5, 2