## Routine First Antenatal Visit Investigations ### Standard Investigations at Booking Visit **Key Point:** The first antenatal visit (booking visit, typically before 12 weeks) includes baseline investigations to establish maternal health status and screen for infections and anemia. ### Correct Investigations at First Visit | Investigation | Purpose | Timing | | --- | --- | --- | | Blood group & antibody screen | Identify blood type, detect alloimmunization | First visit | | Serological tests (syphilis, HIV, HBsAg) | Screen for transmissible infections | First visit | | Full blood count | Assess hemoglobin, detect anemia | First visit | | Urine microscopy & culture | Screen for asymptomatic bacteriuria | First visit | | Blood pressure & weight | Baseline measurements | First visit | ### Glucose Tolerance Testing — Timing **High-Yield:** Glucose tolerance testing (GTT) or fasting blood glucose is performed at **24–28 weeks gestation**, not at the first antenatal visit. This is the standard window for screening gestational diabetes mellitus (GDM) in most guidelines, including ICMR and WHO recommendations. **Clinical Pearl:** A fasting blood glucose at the first visit may be done to rule out pre-existing diabetes, but the formal 2-hour post-load GTT for GDM screening is deferred to the second trimester. **Warning:** Confusing the timing of GDM screening is a common trap. First visit = baseline investigations; 24–28 weeks = GDM screening. ### Summary Options 0, 1, and 3 (blood group/antibody, serology, FBC) are all performed at the first visit. Option 2 (formal GTT with 2-hour post-load) is NOT a first-visit investigation in routine low-risk pregnancies — it belongs at 24–28 weeks. [cite:Williams Obstetrics 26e Ch 8; ICMR Guidelines on Antenatal Care]
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