New criteria for the use of ultrasonography to assess prenatal viability, introduced by the Society of Radiologists in Ultrasound, will help ensure obstetricians are not too hasty in determining that an embryo has ceased developing.
Guidelines for Transvaginal Ultrasonographic (TVUS) Diagnosis of Pregnancy Failure in a Woman with an Intrauterine Pregnancy of Uncertain Viability.
Findings Diagnostic of Pregnancy Failure
- Crown–rump length of >/=7 mm and no heartbeat
- Mean sac diameter of >/=25 mm and no embryo
- Absence of embryo with heartbeat >/=2 wk after a scan that showed a gestational sac without a yolk sac
- Absence of embryo with heartbeat >/=11 days after a scan that showed a gestational sac with a yolk sac
Findings Suspicious for, but Not Diagnostic of, Pregnancy Failure*
- Crown–rump length of <7 mm and no heartbeat
- Mean sac diameter of 16–24 mm and no embryo
- Absence of embryo with heartbeat 7–13 days after a scan that showed a gestational sac without a yolk sac
- Absence of embryo with heartbeat 7–10 days after a scan that showed a gestational sac with a yolk sac
- Absence of embryo >/=6 wk after last menstrual period
- Empty amnion (amnion seen adjacent to yolk sac, with no visible embryo)
- Enlarged yolk sac (>7 mm)
- Small gestational sac in relation to the size of the embryo (<5 mm difference between mean sac diameter and crown–rump length)
* When there are findings suspicious for pregnancy failure, follow-up ultrasonography at 7 to 10 days to assess the pregnancy for viability is generally appropriate.
- Doubilet PM, Benson CB, Bourne T, Blaivas M; Society of Radiologists in Ultrasound Multispecialty Panel on Early First Trimester Diagnosis of Miscarriage and Exclusion of a Viable Intrauterine Pregnancy, Barnhart KT, Benacerraf BR, Brown DL, Filly RA, Fox JC, Goldstein SR, Kendall JL, Lyons EA, Porter MB, Pretorius DH, Timor-Tritsch IE. Diagnostic criteria for nonviable pregnancy early in the first trimester. N Engl J Med. 2013 Oct 10;369(15):1443-51. [Medline]
- Abdallah Y, Daemen A, Kirk E, Pexsters A, Naji O, Stalder C, Gould D, Ahmed S, Guha S, Syed S, Bottomley C, Timmerman D, Bourne T. Limitations of current definitions of miscarriage using mean gestational sac diameter and crown-rump length measurements: a multicenter observational study. Ultrasound Obstet Gynecol. 2011 Nov;38(5):497-502. [Medline]
Created Oct 29, 2013.