Chemical zona pellucida thinning with acidified Tyrode's solution: comparison between partial and circumferential techniques.
OBJECTIVE
To compare effectiveness of two different chemical zona thinning techniques.


METHODS
We studied 163 patients who had experienced IVF or ICSI failures in two or more cycles. Patients were assigned to one of three groups: zona intact (n=72), partial thinning (n=59), or circumferential thinning (n=73). Before transfer, the zonae pellucidae of embryos were thinned partially or circumferentially using acidified Tyrode's solution.


RESULTS
Implantation rates were 8.9% in the intact zona group, 17.6% in the partial thinning group, and 11.9% in the circumferential thinning group: respective clinical pregnancy rates were 16.7% (12/72), 32.2% (19/59), and 27.4% (20/73). Both rates were significantly higher in the partial thinning group than the intact zona group. For circumferential thinning versus zona intact groups, differences fell short of significance.


CONCLUSIONS
Following embryo transfer failure, partial thinning would be recommended over circumferential thinning for successful assisted hatching.
Yano
Kohji
K
IVF Center, Yano Maternity Clinic, 72-1 Shouwa-machi, Matsuyama, Ehime 790-0872, Japan. koyano@ehime.med.or.jp
Yano
Chieko
C
Kubo
Toshiko
T
Ohashi
Ikuko
I
Maeda
Nagamasa
N
Fukaya
Takao
T
D000328:Adult; D010064:Embryo Implantation / Q000187:drug effects*; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D007552:Isotonic Solutions / Q000494:pharmacology*; D011247:Pregnancy; D018873:Pregnancy Rate; D020554:Sperm Injections, Intracytoplasmic; D015044:Zona Pellucida / Q000187:drug effects* / Q000648:ultrastructure
D007552:Isotonic Solutions; C037692:Tyrode's solution
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