RESUMO
OBJECTIVE: Cryopreservation of human spermatozoa is fundamental in assisted reproductive technology. At present, slow freezing techniques are widely used for sperm cryopreservation. Recently, sperm vitrification has been proposed as an alternative to slow freezing. This study aimed to compare the efficiency of slow versus ultra-rapid freezing after thawing and to determine the level of DNA fragmentation in post-thaw normal human semen samples processed through each of the cryopreservation techniques. METHODS: Ultra-rapid freezing is a method that only differs from conventional ultra-rapid freezing in the use of sucrose as a cryoprotectant. In experiment 1, 24 semen samples were used to compare sperm recovery rates after slow and ultra-rapid sperm freezing. In experiment 2, 18 semen samples were used to compare post-thaw sperm DNA fragmentation levels after each of the cryopreservation techniques. RESULTS: In experiment 1, no significant differences were observed in sperm concentration recovery rates, although slow freezing showed a lower progressive motility rate than ultra-rapid freezing (16.6±7.4% vs. 34.7±10.2%), and higher non-progressive and immotile sperm counts (9.0±4.0% vs. 7.6±2.8%; and 74.4±10.1% vs. 57.8±10.3%, respectively). In experiment 2, sperm DNA fragmentation after thawing was significantly higher in slow freezing than in fresh post gradient processing and ultra-rapid freezing samples (47.3±13.4% vs. 9.1±3.7% vs. 14.6±4.6%, respectively). CONCLUSION: Sperm ultra-rapid freezing may be an alternative to slow freezing with better recovery results and less apparent DNA damage.
Assuntos
Criopreservação/métodos , Preservação do Sêmen/métodos , Fragmentação do DNA , Humanos , Masculino , Análise do Sêmen , Espermatozoides/citologia , Espermatozoides/fisiologiaRESUMO
OBJECTIVE: To define the appropriate number of embryos to be transferred at day 5. METHODS: Retrospective analysis of 784 consecutive fresh day-5 embryo transfers performed between 2007 and 2015, divided in three groups: Group A (N = 219): received the only 2 embryos that reached a transferable stage; Group B (N = 357): received 2 selected embryos among several that reached a transferable stage; Group C (N = 208): received the only 3 developing embryos. Clinical pregnancy, implantation, multiple pregnancy and delivery rates were registered. Kruskal-Wallis and Fisher Exact tests were applied as appropriate. RESULTS: Age and previous attempts were comparable in the 3 groups. Compared with Group A, Groups B and C had a higher oocyte recovery (10.7 ± 5.6 vs. 14.7 ± 8.0 vs. 13.8 ± 6.6), fertilization rate (75.97% vs. 81.60% vs. 83.29%) and percentage of embryos reaching a transferable stage on day 5 (39.98% vs. 63.99% vs. 60.97%), as well as a significantly higher clinical pregnancy (42.92% vs. 61.06% vs. 58.17%) and implantation rates (21.09% vs. 40.98% vs. 36.97%). The multiple pregnancy rate was higher in Groups B and C than in Group A (11.70% vs. 31.19% vs. 37.19%). The high order multiple pregnancy rate (> 2) was significantly increased in group C (1.06% vs. 0.92% vs. 14.05%). CONCLUSIONS: In patients with 3 or more day 5 developing embryos, delivery rates are similar if 2 or 3 embryos are transferred. The transfer of 3 embryos carries an unacceptable increase in the risk of high order multiple pregnancy, with its known consequences. According to our data, we should not exceed the number of 2 day-5 fresh embryos transferred.