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Updated: Jun 16, 2026
In Vitro Model of Coronary Angiogenesis
Published on: March 10, 2020
The yolk stalk sign: evidence of death in small embryos without heartbeats
Marcus R Filly1, Peter W Callen, N Tugce Yegul
1Department of Radiology and Biomedical Imaging, University of California, 505 Parnassus Ave, San Francisco, CA 94143-0628 USA. roy.filly@radiology.ucsf.edu
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.
