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Fertilization failure following ICSI is a rare event
Observed fertilization rates using conventional ICSI: up to 80% Clinical pregnancy rates >50% (blastocyst culture)
Total fertilization failure occurs in 1 – 3% of conventional ICSI cycles Low fertilization rate (<33%) occurs in 5% of conventional ICSI cycles
Example of high risk of total fertilization failure = globozoospermia
Dam et al., 2007; Vanden Meerschaut et al., 2014
Failure of sperm‐induced oocyte activation is the main cause of ICSI fertilization failure
Cause of fertilization failure
Prevalence, %
Manifestation
Failed oocyte activation
15 – 66
No PN, 3 PN due to absence of 2nd PB extrusion
Failed sperm head decondensation
4 – 45
No PN, single female PN
Premature sperm chromatin condensation
2 – 23
No PN, single female PN
Spindle defects / sperm aster defects
6 – 18
No PN, failed apposition of PN
Sperm ejection
6 – 23
No PN, single female PN
• Technical failure of sperm injection
• Insufficient number of: mature or normal oocytes / motile sperm
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