While there is much information and discussion on pregnancy failure after assisted reproductive technologies, less emphasis is placed on the failure to collect oocytes after apparently successful ovarian stimulation. This retrospective survey reviewed 4973 treatment cycles in order to obtain information about the likelihood of this event. Overall 42 women (43 treatment cycles) failed to have oocytes collected [0.86% of treatments started and 0.92% of women given human chorionic gonadotrophin (HCG)]. However, in only six cases was this failure unexpected (0.1%) with no obvious potential clinical reason (i.e. all six cases had: HCG administered; more than two follicles >15 mm in diameter; oestradiol values >2000 pmol/l; <38 years old; normal body mass index). Indifference concerning uncommon events is fraught with peril, as although rare, the particular outcome may be devastating to the individual, both economically and psychologically. Eighteen of the 42 women did not return for on-going treatment suggesting increased contact by clinic staff may be required when oocyte retrieval is not achieved. These data suggest that the failure to collect oocytes after apparently successful ovarian stimulation is rare and random. The information has proved useful in allaying the fears of couples contemplating assisted reproductive technologies.
Times have been defined for the handling of 0.25 ml embryo cryostraws and semen, in either 0.5 ml cryostraws or 1.0 ml cryovials containing 0.5 ml material, before potentially detrimental changes in temperature take place. When handling cryovials the time lag is relatively long, with 78.8 +/- 2.6 s being available to manipulate the vials before -80 degrees C is reached and 335.4 +/- 3. 8 s until the eutectic point (approximately -7 degrees C) is reached. However the situation with cryostraws is less tolerant. Both 0.25 and 0.5 ml versions reach temperatures >-80 degrees C within 40 s, and the eutectic point is reached in 79.0 +/- 2.0 s in 0.25 ml cryostraws. These time/temperature data have proved useful in educating new technicians, as well as clinicians and nurses who may also handle frozen human material, in the need to minimize the ambient temperature exposure time of stored specimens so as to maintain optimal post-thaw viability.
Because the range of values was large and the data often skewed, neither inhibin dimer has discriminatory power to reflect the potential of the oocyte.
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