From the Guidelines
For a pregnant woman's first visit in the first trimester, the basic investigations should include a complete blood count (CBC), blood type and Rh factor, rubella immunity status, hepatitis B surface antigen, HIV test, syphilis screening, urine culture and urinalysis, chlamydia and gonorrhea screening, and an ultrasound to confirm pregnancy and gestational age, as these tests help establish baseline health status and identify potential risks 1. The following investigations are recommended:
- Complete blood count (CBC)
- Blood type and Rh factor
- Rubella immunity status
- Hepatitis B surface antigen
- HIV test
- Syphilis screening
- Urine culture and urinalysis
- Chlamydia and gonorrhea screening
- Pap smear (if not done recently)
- Ultrasound to confirm pregnancy and gestational age Additionally, genetic screening options such as cell-free DNA testing or first-trimester combined screening for chromosomal abnormalities should be offered, as they allow for early detection of potential chromosomal abnormalities 1. It is also essential to check thyroid-stimulating hormone (TSH) levels, especially in women with a history of thyroid issues, and test for undiagnosed prediabetes and diabetes at the first prenatal visit in those with risk factors using standard diagnostic criteria 1. These tests help establish baseline health status, identify potential risks, and ensure appropriate care throughout pregnancy. The blood tests assess for anemia, infection risks, and immunities. Urine tests check for urinary tract infections and proteinuria. Early ultrasound confirms viable intrauterine pregnancy and accurate dating. Ensure to discuss lifestyle factors, prenatal vitamins (especially folic acid 400-800 mcg daily), and any medications the woman is taking. Schedule follow-up appointments and provide education on pregnancy expectations and warning signs.
From the Research
Basic Investigations for Pregnant Women in the First Trimester
The following are the basic investigations for a pregnant woman in her first trimester during the initial visit:
- Ultrasound scan to confirm pregnancy, gestational age, and fetal viability 2, 3
- Complete blood count to screen for anemia 4
- Blood work to evaluate the well-being of the fetus 5
Screening for Anemia
Anemia is a common condition in pregnancy, and screening is recommended in the first trimester 4. The American College of Obstetricians and Gynecologists recommends screening for anemia with a complete blood count in the first trimester.
Screening for Diabetes
There is limited evidence on the use of HbA1c as a screening tool for undiagnosed diabetes in the first trimester of pregnancy 6. Therefore, it is not recommended to use HbA1c as a screening tool for diabetes in the first trimester.
Ultrasound Assessment of Gestational Age
Ultrasound assessment of gestational age is very accurate and is marginally better in the first trimester compared with the second 3. First-trimester ultrasound scans can detect fetal structural abnormalities, including abdominal wall defects, nervous system defects, and cardiac defects 2.
Patient Expectations
Patients presenting to the emergency department with first-trimester vaginal bleeding often expect an ultrasound and blood work to evaluate the well-being of their fetus 5. They also want to know if they are having a miscarriage. Emergency physicians should be aware of these expectations to manage patient concerns and improve patient satisfaction.