Relevance of the site of assisted hatching in thawed human blastocysts: a preliminary report.

Preliminary data from a prospective randomized study of assisted hatching (AH) of thawed human blastocysts demonstrated that the rate of complete hatching was significantly higher for AH performed near the inner cell mass (ICM) than for AH at the side opposite to the ICM. This suggests the existence of polarity in the hatching process in human blastocysts, which requires further evaluation.