The empty amnion sign is a sonographic observation where there is visualization of an amniotic sac without concomitant visualization of an embryo. It is an indicator pregnancy failure regardless of the mean sac diameter and is considered to have a sufficiently high positive predictive value 2.
- 1. Mckenna KM, Feldstein VA, Goldstein RB et-al. The empty amnion: a sign of early pregnancy failure. J Ultrasound Med. 1995;14 (2): 117-21. J Ultrasound Med (abstract) - Pubmed citation
- 2. Yegul NT, Filly RA. Further observations on the empty "amnion sign". J Clin Ultrasound. 38 (3): 113-7. doi:10.1002/jcu.20673 - Pubmed citation