Relation between types of yolk sac abnormalities and early embryonic morphology in first-trimester missed miscarriage

The aim of this study was to identify yolk sac (YS) abnormalities and analyze their relation with different embryonic morphologies detected by ultrasonography in first-trimester missed miscarriage.

This descriptive study was carried out on 204 women with established first-trimester missed miscarriage. Ultrasonography depicted the YS's diameter, shape, and echogenicity, as well as the embryonic morphologic findings, including normal shape, isolated defects, and growth disorganization types 1 to 4. The findings were qualified and analyzed.

Abnormalities in YS diameter were much more common than those in YS shape or echogenicity. YS with normal diameter constituted 30.9% of the cases, as opposed to a vast majority with normal shape and normal echogenicity (93.5% and 94.7%, respectively). YS of normal diameter, shape and echogenicity were most commonly (47.5%) associated with normal embryonic morphology. Absent YS was most commonly (75%) associated with growth disorganization type 1. Too-small YS were most prevalent among normal embryos (44.8%) and type 1 growth disorganization embryos (27.6%). Cystic YS were mostly associated with isolated embryonic anomalies (36.8%).

This study found a significant relation between YS abnormalities and embryonic morphology in missed miscarriage cases. This was most evident with abnormalities in YS diameter rather than the YS shape or appearance. The commonest combinations met in our cases were growth disorganized 1 embryos with an absent YS, normal embryonic morphology with normal or small YS, and isolated embryonic defects with cystic YS.