IMPORTANT VALUES IN OB/GYN ULTRASOUND


OBSTETRICS:


Discriminatory Values                        Endovag     Transab

Detection of gestational sac - hCG       1,000 IU/L    3,000 IU/L

Detection of yolk sac - hCG                  7,000 IU/L

Detection of embryo - hCG                   11,000 IU/L

Detection of yolk sac - MSD                  8 mm

Detection of embryo - MSD                  16 mm           25 mm

Detection of cardiac activity - CRL        5 mm            9 mm


New Criteria for Nonviable Pregnancy*:

  1. CRL ≥7 mm + NO heartbeat

  2. MSD ≥25 mm + NO embryo

  3. NO embryo with cardiac activity ≥2 weeks post scan with a GS w/o YS

  4. NO embryo with cardiac activity ≥11 days post a scan with a GS + YS


Suspicious for, but not diagnostic of pregnancy failure*:

  1. CRL <7 mm + NO heartbeat

  2. MSD of 16–24 mm + NO embryo

  3. NO embryo with cardiac activity 7–13 days after a scan that showed a GS w/o YS

  4. NO embryo with cardiac activity 7–10 days after a scan that showed a GS + YS

  5. Absence of embryo ≥6 wk after last menstrual period

  6. Empty amnion (amnion seen adjacent to yolk sac, with no visible embryo)

  7. Enlarged yolk sac (>7 mm)

  8. Small gestational sac (<5 mm difference between MSD and CRL)


*Diagnostic Criteria for Nonviable Pregnancy Early in the First Trimester (N Engl J Med 2013; 369:1443-1451)


Fetal Brain (>=16 weeks):

Width of lateral ventricle           ≤ 10 mm

Cisterna Magna                        2-10 mm


Fetal Neck:   

Nuchal fold (14-20 weeks)                   < 6 mm

Nuchal translucency (10-14 weeks)     < 3 mm


Cervical length in pregnancy:            > 3 cm


Embryonic Heart Rate:

CRL < 5 mm        > 80 bpm

CRL 5-9 mm        > 100 bpm

CRL 10-15 mm    > 110 bpm


GYNECOLOGY:


Adult ovary                                    < 23 cc

Post-menopausal endometrium    < 5 mm