The Expanded Amnion Sign

Abstract

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.

Predictive value of presence of amniotic sac without visible embryonic heartbeat in diagnosis of early embryonic demise

“…Our findings are concordant with those of McKenna et al 11 . and Yegul and Filly 12 , who also demonstrated that detecting an amniotic sac in the absence of a live embryo is accurate in diagnosing miscarriage. However, these previous studies were retrospective in design and were published before the current criteria for diagnosis of miscarriage were in use.…”

“…We estimated that we would need to recruit a minimum of 520 women with a pregnancy of uncertain viability, assuming 15% prevalence 12 of the finding of an amniotic sac with no live embryo, and specificity of 90% for the diagnosis of EED with a 3% margin of error and loss to follow‐up rate of 15% 15 . We sought advice from the Joint Research Office of University College London and University College London Hospital, London, UK regarding ethical approval and were advised that formal ethics approval was not needed for this study, as the data were collected as part of routine clinical care, were anonymized and were analyzed within the clinical care team.…”

“…Follow‐up of all these cases confirmed the diagnosis of EED. Another study by Yegul and Filly 12 showed that, in their study population of 108 women, all pregnancies with a visible amniotic sac containing an embryo without cardiac activity ended in miscarriage.…”