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J Assist Reprod Genet. 2000 Nov;17(10):557-60.

Zona thinning with noncontact diode laser in patients aged < or = 37 years with no previous failure of implantation: a prospective randomized study.

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  • 1Center for Human Reproduction, Sinhá Junqueira Maternity Foundation, Rua D. Alberto Gonçalves, 1500/CEP 14085-100, Ribeirão Preto, SP, Brazil.



Zona thinning (ZT) is a technique used to improve pregnancy rates among patients > or = 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.


A total of 103 patients submitted to ICSI for the first time and those aged < or = 37 years 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-micron wavelength (Fertilaser) was used for the procedure); group II, patients with no ZT (n = 52). In both groups, embryo transfer was performed on the second day.


The age of group I patients (31.8 +/- 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 I (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 microns) did not differ (P = 0.08) from that of group II embryos (17.1 +/- 1.7 microns). The rate of embryo implantation (20.8%) and the rate of clinical pregnancy per embryo transfer (40.3%) were higher for group II than for group I (17.7% and 33.3%, respectively), but the difference was not significant (P = 0.55 and P = 0.54).


These results suggest that ZT in the population aged < or = 37 years and with no previous failure of implantation may have no impact on intracytoplasmic sperm injection success rates.

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