The effect of long zona dissection using ICSI pipettes for mechanical assisted hatching in vitrified-thawed blastocyst transfers

Objective

To investigate the effect of long zona dissection (LZD) compared with partial zona dissection (PZD) using ICSI pipettes for mechanical assisted hatching (AH) in vitrified-thawed blastocyst transfers.

Design

Prospective study.

Setting

University IVF clinic.

Patient(s)

A total of 120 women ≦ 38 years old undergone vitrified-thawed blastocyst transfers with LZD or PZD.

Intervention(s)

The culture of all pronucleate embryos to the blastocyst stage and the selection of blastocysts ≧ grade 3BB (Gardner and Schoolcraft score), followed by vitrified-thawed blastocyst transfers with LZD (n = 60) or with PZD (n = 60)

Main outcome measure(s)

Complete hatching rates, implantation rates, pregnancy rates.

Result(s)

At 5 h after thawing, complete hatching rates of blastocysts were significantly higher in LZD group compared with PZD group, 52.4 % vs. 31.8 % (P = 0.001). Implantation and clinical pregnancy rates were significantly higher in LZD group compared with PZD group, 40.9 % vs. 25.7 % and 63.0 % vs. 40.0 %, respectively (P = 0.010, P = 0.011).

Conclusion(s)

LZD using ICSI pipettes for mechanical AH improves significantly complete hatching, implantation and pregnancy rates in vitrified-thawed blastocyst transfers.