P. Labella

Oocyte cryopreservation outcomes including pre-cryopreservation and post-thaw meiotic spindle evaluation following slow cooling and vitrification of human oocytes

OBJECTIVE To report our oocyte cryopreservation (OC) outcomes including meiotic spindle (MS) evaluation of metaphase II (MII) oocytes destined for OC and thaw. DESIGN Retrospective. SETTING University-based infertility center. PATIENT(S) Women attempting pregnancy using cryopreserved oocytes. INTERVENTION(S) OC, MS evaluation. MAIN OUTCOME MEASURE(S) Survival, two pronuclear (2PN) fertilization, achieving embryo quality suitable for transfer or refreezing, blastocyst formation. RESULT(S) Thirty-two OC-thaw cycles resulted in 20 pregnancies, 18 either ongoing or delivered. In 26 cycles, MS evaluation was performed: 262/303 (86%) thawed/recovered oocytes survived, 218/262 (83%) achieved 2PN fertilization, 133/218 (61%) became suitable for day-3 and 122/218 (56%) for day-5 transfer. In total, 58 embryos were transferred resulting in a 62% pregnancy and a 41% implantation rate. Of oocytes evaluated before cryopreservation, 247 (82%) were spindle-positive; 96% of these were also spindle-positive after thawing. Blastocyst formation and suitability for day-5 transfer was achieved more often if a post-thaw spindle was visualized. Of all slow-cooled and vitrified oocytes, a higher percentage of those slow-cooled achieved 2PN fertilization and usability. MS evaluation of oocytes cryopreserved by either method was associated with similar outcomes. CONCLUSION(S) OC outcomes are improving. An MS was almost always exhibited both before cryopreservation and after thawing, suggesting that, with appropriate technique, OC presents minimal harm to the MII oocyte. A meiotic spindle evaluation might help to further OC technology.

Successful Oocyte Cryopreservation in Reproductive-Aged Cancer Survivors.

OBJECTIVE: To demonstrate that oocyte cryopreservation is a feasible reproductive option for patients with cancer of childbearing age who require gonadotoxic therapies. METHODS: This study is a university-based retrospective review of reproductive-aged cancer patient treatment cycles that included ovarian stimulation, transvaginal oocyte retrieval, oocyte cryopreservation, and, in some cases, subsequent oocyte thaw, in vitro fertilization, and embryo transfer. Outcome measures included ovarian stimulation response, number of oocytes retrieved, cryopreserved, and thawed, and pregnancy data. RESULTS: From 2005 to 2014, 176 reproductive-aged patients with cancer (median age 31 years, interquartile range 24–36) completed 182 oocyte cryopreservation cycles. Median time between consult request and oocyte retrieval was 12 days (interquartile range 10–14). Median peak stimulation estradiol was 1,446 pg/mL (interquartile range 730–2,687); 15 (interquartile range 9–23) oocytes were retrieved and 10 (interquartile range 5–18) metaphase II oocytes were cryopreserved per cycle. Ten patients (11 cycles) have returned to attempt pregnancy with their cryopreserved oocytes. Among thawed oocytes, the cryopreservation survival rate was 86% (confidence interval [CI] 78–94%). Nine of 11 thaw cycles resulted in embryos suitable for transfer. The embryo implantation rate was 27% (CI 8–46%) and the live birth rate was 44% (CI 12–77%) per embryo transfer. Chance for live birth with embryos created from cryopreserved oocytes was similar between the patients with cancer in this study and noncancer patients who underwent the same treatment at our center (44% [CI 12–77%] compared with 33% [CI 22–44%] per embryo transfer). CONCLUSION: Oocyte cryopreservation is now a feasible fertility preservation option for reproductive-aged patients with cancer who require gonadotoxic therapies.