At what minimum serum beta-hCG level (the discriminatory zone) should a transvaginal ultrasound reliably demonstrate an intrauterine gestational sac in a singleton pregnancy?

• A 6000 to 6500 mIU/mL
• B 3500 to 4000 mIU/mL
• C 1500 to 2000 mIU/mL ✓
• D 500 to 800 mIU/mL

Explanation

With transvaginal scanning, an intrauterine gestational sac should be visible once beta-hCG reaches approximately 1500 to 2000 mIU/mL (First International Reference Preparation). Above this threshold with an empty uterus, an ectopic pregnancy must be strongly suspected. The higher values given correspond roughly to the older abdominal-scanning discriminatory zone, not the transvaginal standard.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.