The Usefulness of Assisted Hatching in Cryopreserved Embryo Transfer

Abstract: Assisted hatching (AH) is becoming an established technique for the rescue of failed hatching, although its usefulness is still under debate. To investigate the usefulness of AH, we compared hatching rates, pregnancy rates, and abortion rates, depending on whether AH had been performed, in 413 patients (681 cycles) who received cryopreserved embryo transfer at our clinic from September 2011. The hatching rate was 60.6% in the AH group versus 2.9% in the non-AH group (P<0.005), a significantly higher rate in the former group. Moreover, hatching rates were 67.7% vs. 0.0% in patients aged ≤29 years, 69.2% vs. 0.0% in patients aged 30–34 years, 60.1% vs. 2.1% in patients aged 35–39 years, and 51.1% vs. 8.7% in patients aged ≥40 years, showing that the rates were significantly higher across all ages in the AH group (P<0.005). Hatching rates according to Gardner's classification were 42.5% vs. 0.0% for grade ≤2, 53.9% vs. 0.0% for grade 3, and 69.4% vs. 4.9% for grade 4, also indicating significantly ...