The yolk stalk sign: evidence of death in small embryos without heartbeats.
OBJECTIVE
The purpose of this study was to assess the positive predictive value for confirming early embryonic death in the clinical sonographic scenario wherein an embryo is identified without a visible heartbeat; the embryonic crown-rump length (CRL) is 5 mm or less; and the embryo is not immediately adjacent to the yolk sac.


METHODS
A retrospective study of 882 first-trimester sonograms was performed among women who had an intrauterine pregnancy of uncertain viability based on 1 or more sonographic findings (eg, no visible heartbeat in an embryo with a CRL of < or =5 mm). Eight hundred six cases met the inclusion criteria.


RESULTS
Among the cohort of 806 cases, 520 (64.5%) had an identifiable embryo. One hundred fifty-nine of these embryos had no demonstrable heartbeat and a CRL of 5 mm or less. The CRLs of these embryos ranged from 1.7 to 5.4 mm. This cohort's sonograms were reviewed to determine whether there was a separation between the embryo and yolk sac. Twenty-one cases were discovered. Recall that as a retrospective study, no specific effort was made to show this finding. Thus, a computation of the sensitivity of this finding would result in an underestimate of indeterminate magnitude. All of these cases were subsequently proven to be failed pregnancies.


CONCLUSIONS
The positive predictive value of the "yolk stalk sign" in determining early pregnancy failure for an embryo with a CRL of 5 mm or less and no visible heartbeat was 100% in this cohort.
Filly
Marcus R
MR
Department of Radiology and Biomedical Imaging, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628 USA. roy.filly@radiology.ucsf.edu
Callen
Peter W
PW
Yegul
N Tugce
NT
Filly
Roy A
RA
D015148:Cardiotocography / Q000706:statistics & numerical data*; D005321:Extraembryonic Membranes / Q000000981:diagnostic imaging*; D005260:Female; D005313:Fetal Death / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D009820:Ohio / Q000453:epidemiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000706:statistics & numerical data*