title: Effect of artificial shrinkage on clinical outcome in fresh blastocyst transfer cycles.
abstract: OBJECTIVE
  This study aimed to determine the safety and clinical effect of artificial shrinkage (AS) in terms of assisted hatching of fresh blastocysts. Also, we evaluated the correlation between patient age and the effect of AS on clinical outcome.
  
  
  METHODS
  Two AS methods, using a 29-gauge needle and laser pulse, were compared. Seventy-three blastocysts were shrunk using a 29-gauge needle and the same number of other blastocysts were shrunk by a laser pulse. We evaluated the shrunken blastocysts hourly and considered them viable if they re-expanded >70%. Blastocyst transfer cycles (n=134) were divided into two groups: a control group consisted of the cycles whose intact embryos were transferred (n=100), while the AS group consisted of the cycles whose embryos were replaced following AS (n=34). The implantation and pregnancy rates of the control group and AS group were compared (p<0.05).
  
  
  RESULTS
  The re-expansion rates of the 29-gauge needle and laser pulse AS groups were similar (56 [76.7%] vs. 62 [84.9%], respectively). All of the remaining shrunken blastocysts were re-expanded within 2 hours. There was no degeneration of shrunken blastocysts. The total and clinical pregnancy rate of the AS group (23 [67.6%]; 20 [58.8%], respectively) was significantly higher than that of the control group (47 [47.0%]; 39 [39.0%], respectively). In the older patient group, there was no difference in the clinical outcomes between the AS and control groups.
  
  
  CONCLUSIONS
  These results suggest that AS of blastocoele cavity, followed by the transfer, would be a useful approach to improve the clinical outcome in cycles in which fresh blastocyst stage embryos are transferred.
authors.affiliation: Maria Fertility Hospital, Seoul, Korea.
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Hur
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Ryu
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Yoon
authors.forename: San Hyun
authors.initials: SH
authors.lastname: Yoon
authors.forename: Chang Young
authors.initials: CY
authors.lastname: Hur
authors.forename: Won Don
authors.initials: WD
authors.lastname: Lee
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Lim