The expanded amnion sign: evidence of early embryonic death.
OBJECTIVE
The purpose of this study was to assess the positive predictive value for confirming early embryonic death in the clinical scenario wherein an embryo is identified without a visible heartbeat, but the embryonic crown-rump length (CRL) is 5 mm or less.


METHODS
We conducted a retrospective study of 882 first-trimester sonograms with abnormal findings among women who were threatening to abort. Eight hundred six met the inclusion criteria.


RESULTS
Among the cohort of 806 cases, 520 (64.5%) had an identifiable embryo, and 255 of those with an identifiable embryo had a visible amnion (49.0%). One hundred sixteen of the 255 with a visible amnion and an identifiable embryo without a heartbeat had a CRL that measured 5 mm or less (45.5%). The CRL of these embryos ranged from 1.7 to 5.4 mm (ie, when rounded to the nearest millimeter, these embryos would be 5 mm) with the breakdown as follows: those measuring less than or equal to 3.4 mm (n = 28), those measuring 3.5 to 4.4 mm (n = 45), and those measuring 4.5 to 5.4 mm (n = 43). Eight of these 116 patients did not have any documented follow-up. In the remaining 108 patients, pregnancy failure was confirmed.


CONCLUSIONS
We conclude that any embryo that is surrounded by an amnion and that also lacks a heartbeat has unfortunately but definitively died. This is equally true for embryos measuring less than 5 mm in CRL.
Department of Radiology, University of California, San Francisco, CA 94143-0628 USA.
N Tugce
NT
Yegul
Roy A
RA
Filly
D000650:Amnion / Q000000981:diagnostic imaging*; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D020964:Embryo Loss / Q000000981:diagnostic imaging* / Q000401:mortality*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000706:statistics & numerical data*