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Department of Emergency Medicine

Limited Bedside Transvaginal Ultrasound 

Correlation of Gestational Age, b-HCG level, and TVUS findings

 Gestational age  B-HCG (mIU/ml)  TVUS findings
 4.5-5 weeks  <1,000  Gestational sac
 5 weeks  1,000-2,000  Gestational sac + DDS*
 5-6 weeks  >2,000  Yolk sac** (+/- fetal pole)
 6 weeks  10,000-20,000  Embryo with cardiac activity
 7 weeks  >20,000  Embryonic torso/head



**DDS = double *DDS = double decidual sign
**First definitive evidence of IUP


  • B-HCG of 1,500 is considered the discriminatory zone, i.e. minimum quantitative level of HCG at which intrauterine pregnancy should be seen by ultrasound. 
  • Abnormal gestation or embryonic demise if:
    • Gestational sac > 10 mm without a yolk sac
    • Gestational sac > 18 mm without a fetal pole
    • Fetal pole > 5 mm without cardiac activity
  • If the B-HCG is > 1500 and no GS is seen
    • Ectopic pregnancy
    • Completed abortion
  • If the B-HCG is < 1500 and the uterus is empty
    • Early normal pregnancy
    • Ectopic pregnancy
    • Completed abortion
  • Serial B-HCG value in 48 hours
    • Live IUP: doubles
    • Completed abortion: decreases
    • Ectopic pregnancy: stable or small rise

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