title: Estimation of second polar body retention rate after conventional insemination and intracytoplasmic sperm injection: in vitro observations from more than 5000 human oocytes.
abstract: OBJECTIVE
  Tripronucleate (3pn) development after conventional insemination (CONV) or ICSI was analyzed to estimate the rate of second polar body retention giving rise to 3pn formation.
  
  
  METHODS
  Data from 453 consecutive IVF cycles were reviewed during a 6-month period. Mature oocytes were monitored in ICSI (n = 3195) and CONV (n = 2274) groups by fertilization assessment 16-18 h post-insemination. Ovulation induction protocols and in vitro culture conditions remained constant during the study interval.
  
  
  RESULTS
  Normal (2pn) fertilization occurred in 74.2% and 70.5% for CONV and ICSI groups, respectively (p < 0.003). 1pn formation was observed in 4.5% of CONV oocytes, and 2.5% of ICSI oocytes (p < 0.001); 3pn formation was 8.1% in the CONV group, and 2.5% in the ICSI group (p < 0.0001). We observed 4pn formation in 0.4% of oocytes in the CONV group, but in only 0.04% of oocytes fertilized with ICSI (p < 0.007). Cellular degeneration occurred in 2.4% of oocytes inseminated conventionally, and in 3.5% of oocytes fertilized by ICSI (p = 0.02). Maternal age did not impact pronuclear status.
  
  
  CONCLUSIONS
  We found the 3pn formation rate after ICSI to be approximately one-third that observed in the CONV group. Extrapolating the ICSI data to the CONV data, it may be inferred that 2.5% of 3pn development after CONV was due to second polar body retention. This suggests that 5.6% of CONV oocytes showed dispermic fertilization. Decreasing oocyte quality with increasing maternal age had no apparent influence on any of the fertilization outcomes.
authors.affiliation: Division of Cell Sciences, University of Southampton, Highfield, Southampton, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Porter
authors.forename: Taer
authors.initials: T
authors.lastname: Han
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tucker
authors.forename: James
authors.initials: J
authors.lastname: Graham
authors.forename: Juergen
authors.initials: J
authors.lastname: Liebermann
authors.forename: E Scott
authors.initials: ES
authors.lastname: Sills
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007314:Insemination; D008297:Male; D009865:Oocytes / Q000502:physiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D013094:Spermatozoa