Zona thinning with noncontact diode laser in patients aged ≤37 years with no previous failure of implantation:: A prospective randomized study

Purpose: Zona thinning (ZT) is a technique used to improve pregnancy rates among patients greater than or equal to 38 years old and/or patients presenting previous implantation failure. The objective of the study was to determine whether ZT has a beneficial effect on patients younger than 37 years who are undergoing the first ICSI attempt. Methods: A total of 103 patients submitted to ICSI for the first time and those aged less than or equal to 37years were divided in a prospective and randomized manner into two groups: group I, patients submitted to ZT (n = 51) (a laser diode with 1.48-mum wavelength (Fertilaser) was used for the procedure); group II, patients with no ZT (n = 52). In both groups, embryo transfer was pel formed on the second day. Results: The age of group I patients (32.8 +/- 3.6) did not differ (P = 0.53) from that of group II patients (31.4 +/- 3.6). The number of metaphase II oocytes was similar (P = 0.76) for the two groups (group I = 9.12 +/- 5.27; group II = 8.67 +/- 5.02). The average number of embryos available per transfer of group 1 (6.14 +/- 4.02) did not differ (P = 0.69) from that of group II (5.75 +/- 3.83). The number of embryos transferred was similar (P = 0.61) for the two groups (group I = 2.76 +/- 0.9; group II = 2.87 +/- 0.79). The thickness of the zona pellucida of group I embryos (16.6 +/- 2.2 mum) did not differ (P = 0.08) from that of group II embryos (17.1 +/- 1.7 mum). The rate of embryo implantation (20.8%) and the rate of clinical pregnancy per embryo transfer (40.3%) were higher far group II than for group 1 (17.7% and 33.3%, respectively), brit the difference was not significant (P = 0.55 and P = 0.54). Conclusions: These results suggest that ZT in the population aged less than or equal to 37 years and with no previous failure of implantation may have no impact on intracytoplasmic sperm injection success rates.