Randomized double-blind comparison of laser zona pellucida thinning and breaching in frozen-thawed embryo transfer at the cleavage stage.
OBJECTIVE
To compare the implantation and ongoing pregnancy rates of frozen-thawed embryo transfer (FET) using laser thinning with those of laser breaching of the zona pellucida (ZP).


METHODS
Double-blind randomized study.


METHODS
A tertiary assisted reproduction unit.


METHODS
Infertile patients undergoing FET cycles.


METHODS
In the thinning group, more than a quarter of the ZP's outer half-diameter was removed by using a 1,480-nm noncontact laser, whereas a hole about 30 microm in size was created in the ZP in the breaching group.


METHODS
Implantation and ongoing pregnancy rates.


RESULTS
On the day of the FET, 180 patients were randomly divided into the thinning and breaching groups according to a computer-generated randomization list that was placed in sealed envelopes. The two groups were comparable in terms of demographic characteristics, ovarian response of the stimulated cycle, and quality of fresh and frozen-thawed embryos. The implantation and ongoing pregnancy rates of the thinning group were significantly higher than the corresponding rates of the breaching group but were similar to those of patients without ZP thinning or breaching.


CONCLUSIONS
Laser ZP thinning is associated with significantly higher implantation and ongoing pregnancy rates in FET cycles compared with the case of laser ZP breaching.
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China. Electronic address: nghye@hkucc.hku.hk.
Ernest Hung Yu
EHY
Ng
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
Estella Yee Lan
EYL
Lau
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
William Shu Biu
WSB
Yeung
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
Tak Ming
TM
Cheung
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
Oi Shan
OS
Tang
Department of Obstetrics and Gynaecology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China.
Pak Chung
PC
Ho
D002970:Cleavage Stage, Ovum / Q000502:physiology*; D015925:Cryopreservation / Q000379:methods*; D004311:Double-Blind Method; D010064:Embryo Implantation / Q000502:physiology; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D011247:Pregnancy; D018873:Pregnancy Rate; D015044:Zona Pellucida / Q000502:physiology*