Embryo selection versus natural selection: how do outcomes of comprehensive chromosome screening of blastocysts compare with the analysis of products of conception from early pregnancy loss (dilation and curettage) among an assisted reproductive technology population?

OBJECTIVE: To compare the incidence of numerical chromosomal abnormalities (NCAs) reported after preimplantation genetic screening (PGS) analysis compared with that reported after cytogenetic analysis of products of conception after spontaneous abortion. DESIGN: Retrospective study. SETTING: Private academic in vitro fertilization center. PATIENT(S): Cytogenetic reports of patients who underwent an IVF cycle with PGS of at least one biopsied embryo were compared with cytogenetic analysis reported from patients who had dilation and curettage (D&C) for the treatment of a spontaneous abortion after assisted reproductive technology (ART) treatment. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Frequencies for each numerical chromosomal abnormality from both groups were compared. RESULT(S): A total of 1,069 NCAs were reported after PGS (trisomy 54.3%, monosomy 45.7%, no polyploidies), resulting in a trisomy/monosomy ratio of 0.82. A total of 447 NCAs was reported after D&C (trisomy 83%, polyploidy 10.7%, monosomy 6.3%). The aneuploidies most frequently identified were similar in both groups and included 15, 16, 18, 21, and 22. Monosomies (n = 28, 6.3%) were rarely observed in the group that underwent D&C after ART. CONCLUSION(S): This review provides an analysis of the most commonly identified NCAs after PGS and in first-trimester D&C samples in an infertile population utilizing ART. Although monosomies comprised >50% of all cytogenetic anomalies identified after PGS, there were very few identified in the post-D&C samples. This suggests that although monosomies occur frequently in the IVF population, they commonly do not implant. Despite this difference, this study demonstrated that the specific NCAs observed after PGS analysis and D&C were comparable.

Optimizing human oocyte cryopreservation for fertility preservation patients: should we mature then freeze or freeze then mature?

OBJECTIVE: To evaluate the maturation and post-thaw survival rates of immature oocytes to determine whether in vitro maturation (IVM) should be attempted prior to or after cryopreservation. DESIGN: Nonrandomized observational study. SETTING: Private academic and clinical reproductive center. PATIENT(S): Patients (n = 71) who donated immature unusable oocytes after vaginal oocyte retrieval (VOR) after undergoing controlled ovarian hyperstimulation using a standard GnRH antagonist protocol. INTERVENTION(S): Germinal vesicle (GV), metaphase I (MI), and metaphase II (MII) oocytes (n = 175) were obtained from consenting IVF patients for fresh IVM, post-thaw IVM, or control group. In the fresh IVM group, GV- and MI- stage oocytes (n = 69) were cultured for 24 hours, matured in vitro (IVM-MII), cryopreserved, thawed, and evaluated for survival. In the post-thaw IVM group, GV- and MI- stage oocytes (n = 27) were frozen on day 0, thawed, evaluated for survival, and cultured for 24-hour IVM. MII donor oocytes (n = 79) were cryopreserved and thawed as a control. MAIN OUTCOME MEASURE(S): Survival postfreeze and oocyte development to the MII stage was analyzed using a χ(2) analysis. RESULT(S): Fresh IVM had a significantly higher maturation rate than post-thaw IVM. CONCLUSION(S): Oocyte cryopreservation is important for patients at risk of ovarian cancer, elective fertility preservation, and, potentially, for ovum donation. The superior maturation rate of GV and MI oocytes in the fresh versus post-thaw groups provides strong evidence for maturing oocytes to the MII stage before cryopreservation.

Commercially available enhanced in vitro maturation medium does not improve maturation of germinal vesicle and metaphase I oocytes in standard in vitro fertilization cases.

Improvements in in vitro maturation techniques have focused on culture optimization to increase oocyte maturation rates. Specialized culture media, now commercially available, did not perform significantly better than standard IVF culture media for maturation of immature oocytes in our normal IVF cases.

High pregnancy rates can be achieved after freezing and thawing human blastocysts.

OBJECTIVE: To examine the results of a 3-year trial using blastocyst cryopreservation to limit multiple pregnancy and optimize overall pregnancy per cycle. DESIGN: Retrospective clinical evaluation of pregnancy rates after freezing and thawing human blastocysts. SETTING: Tertiary-care academic center. PATIENT(S): Seven hundred fifty-three different patients treated in 783 IVF cycles with blastocysts frozen from July 2000 to June 2003. INTERVENTION(S): Two thousand, two hundred fifty-nine blastocysts were frozen in cycles in which only blastocysts were cryopreserved (cycles with pronuclear stage oocytes or pre-embryos also cryopreserved were excluded from the analysis). Of these, 628 (27.6%) were thawed in 218 cycles. MAIN OUTCOME MEASURE(S): Pregnancy rate per cycle with thaw. RESULT(S): Four hundred seventy-nine (76.3%) blastocysts survived thawing, and 440 (92.0%) were transferred after exhibiting evidence of survival (most commonly, blastocoele reexpansion). In cycles with a thaw, 211 (96.8%) of 218 underwent intrauterine transfer. An average of 2.09 blastocysts was transferred per replacement. One hundred twenty-five (59.2%) clinical pregnancies were established, which included 23 sets of twins and 5 triplet gestations. Two sets of monozygotic twins were identified after the replacement of a single thawed blastocyst (1.6%). The age of the patient at the time of cryopreservation (<37 years) was an important factor in the establishment of clinical and ongoing pregnancy. The mode of ovarian stimulation, replacement method, and whether blastocysts were frozen on day 5 or day 6 of development did not demonstrate clinical significance. CONCLUSION(S): Cryopreserved and thawed blastocysts demonstrated a similar potential for implantation when compared with fresh pre-embryos on day 3. On the basis of these results, the blastocyst stage of development appears to be optimal for clinical freeze-thaw trials.