Abstract: To investigate the clinical outcome of patients who underwent cryopreservation of all embryos. Methods: A retrospective analysis was made in the clinical data of patients with cryopreservation of all embryos between April 2011 and September 2011 in four hospitals of North China. The patients were divided into five groups according to the reasons of cryopreservation of all embryos: ovarian hyperstimulation syndrome (OHSS) group, serum progesterone elevation group, endometrial group, hydrosalpinx group and others. The clinical pregnancy rate per transfer, implantation rate and cumulative clinical pregnancy rate were analyzed. Results: The clinical pregnancy rate, implantation rate and cumulative clinical pregnancy rate of the OHSS group were 55.4%, 34.8% and 73.7%, respectively. The rates of the serum progesterone elevation group were 25.5%, 11.2% and 43.1%, respectively. The rates of the endometrial group were 54.8%, 34.4% and 61.5%, respectively. The rates of the hydrosalpinx group were 60%, 30% and 60%, respectively. The rates of the other factors group were 36.0%, 24.5% and 44.0%, respectively. Conclusion: The strategy of cryopreservation of all embryos could improve the clinical outcomes of patients with severe OHSS. It still needs a large multicentre, randomized trial to evaluate its effectiveness and side effects, although it has the positive clinical application for other reasons of cryopreservation of all embryos.

Key words: Embryo disposition, Cryopreservation, Fertilization in vitro, Embryo transfer, Treatment outcome