Effects of laser-assisted thinning versus opening on clinical outcomes according to maternal age in patients with repeated implantation failure

Laser-assisted thinning (LAT) and laser-assisted opening (LAO) are performed as part of human in vitro fertilization (IVF) to increase the implantation rate in patients with a poor prognosis and in cases of repeated implantation failure. However, an insufficient number of studies have directly compared LAT and LAO using the same methods. Therefore, we compared the effects of LAT and LAO on clinical outcomes according to maternal age in patients with repeated implantation failure. This retrospective study was performed in 509 IVF cycles (458 patients). The cycles were divided based on maternal age and the method used (< 38 years LAT, n = 119 vs. LAO, n = 179 and ≥ 38 years LAT, n = 72 vs. LAO, n = 139). Cleavage-stage embryos before transfer were either thinned or opened using a 1.46-μm noncontact diode laser. We compared the implantation rates and pregnancy outcomes of cycles between LAT and LAO according to maternal age. The characteristics of patients did not differ significantly among the groups (p > 0.05), with the exception of mixed factor infertility, which was more common in the LAT group than in the LAO group among patients < 38 years of age (10.1% vs. 2.8%, p = 0.008). The LAT and LAO groups showed similar rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, abortion, implantation, singleton pregnancy, and twin pregnancy (p > 0.05). In conclusion, LAT and LAO had similar clinical outcomes. Therefore, we did not find any evidence that LAT is superior to LAO. In fact, the patients ≥ 38 years of age who underwent LAO tended to have a lower abortion rate. Further study is necessary to confirm these results in a larger population.