Wednesday, October 15, 20032:15 P.M.

O-302

Is reduced blastocyst development associated with chromosomal abnor-mality after PGD? Zhen Ye, Jason Park, Nikica Zaninovic, Kang Pu Xu,Lucinda L. Veeck, Zev Rosenwaks. Weill Medical Coll of Cornell Univ,New York, NY.

Objective: Preimplantation genetic diagnosis (PGD) procedures are com-monly used to check for specific genetic diseases and chromosomal abnor-malities. This study was undertaken to determine if preembryo morphologyon day 3 and rate of blastocyst development on day 5 are associated withPGD results.

Design: Retrospective analysis of PGD cycles tested for aneupolidy fromJanuary 2000 to March 2003.

Materials and Methods: Six-hundred nineteen preembryos from seventy-six PGD cycles were divided into two main groups: Normal (preembryodiagnosed as being free of studied chromosomal abnormality), and Abnor-mal (diagnosed as carrying a chromosomal disorder). Each group wassubdivided into three subgroups according to preembryo morphology anddevelopment on days 3 and day 5. The mean age of all patients in this studywas 38.88 � 5.05. Data were compared using Chi-Square statistical anal-ysis.

PGD was performed on day 3. Fluorescent In Situ Hybridization (FISH)techniques, using probes for chromosomes X, Y, 13, 18, and 21 (and often,15, 16, and 22), were used for all diagnoses. Occasionally, probes forchromosome 2, 9, 10, 11, 17, or 20 were added for individual cases.

Results: One hundred ninety-six preembryos (32%) were classified asnormal, four-hundred and three (65%) were shown to be abnormal, andtwenty (3%) had unconfirmed diagnoses. Results are summarized in thetable below.

When a single chromosome abnormality was analyzed in the abnormalgroup, results demonstrated that preembryos with XXY, XYY, monosomiesfor 16, 21, 22, and trisomies for 13, 15, 16, 18, and 22 all were capable ofdeveloping into blastocysts by day 5.

Conclusion: Normal preembryos, as diagnosed using common FISHprobes, appear to develop at faster rates than abnormal ones on days 3 and5. However, the finding that more than 50% of chromosomally abnormalpreembryos are viable and reached morula or blastocyst stages suggests theimportance of aneuploidy screening.

Wednesday, October 15, 20032:30 P.M.

O-303

The impact of media pH on the development of human embryos. AminKhabani, Lynette Scott, Kelly Tufts, Latasha Craig, Michael Soules, MarkKan. Univ of Washington, Seattle, WA.

Objectives: Media used for most procedures in human IVF are bicarbon-ate buffered, resulting in differing pH depending on the CO2 concentration.The internal pH of the cell is estimated at approximately 7.2, thus media areformulated in this range. The operating pH of commercial media range from7.1 to 7.45 when used in a gaseous atmosphere of between 5 and 6% CO2.There has been much debate as to the correct concentration of CO2 foroptimization of IVF results but not on the pH of the media. This studyretrospectively analyzed the effects of media pH on fertilization, implanta-tion, and development of human oocytes and embryos.

Design: At the beginning of each calendar year the incubators werecalibrated to the desired setting (between 5-6% CO2) with a blood gasmachine. Subsequently, adjustments were made to the CO2 to obtain a

media pH between 7.2 and 7.4. The pH of the media used for fertilizationand embryo development was recorded each morning, with fresh mediabeing placed in each incubator daily. For each patient, a mean pH wascalculated from the recordings from the first three days of embryo devel-opment. These pH values were compared to the fertilization rate (FR),implantation rate (IR) and clinical pregnancy rates (CPR).

Results: The results are shown in Table 1. The highest IR and CPRoccurred with a pH recording between 7.3 and 7.4. The average patient age,percentage of ICSI cases, and percentage of blastocyst transfers were similarbetween the five groups.

Table 1.

* � P � 0.05

Conclusions: The pH of the media, over a fine range, has a significantimpact on IR and CPR, but not on fertilization rates. The optimum pH rangewas 7.3-7.4, which is higher than the estimated internal pH of cells, and thepH recommended by many commercially available media. Incubatorsshould be set using pH for QC for tighter control in the IVF laboratory.

Wednesday, October 15, 20032:45 P.M.

O-304

Aneuploidy rates in unfertilized oocytes, from fertile anonymous do-nors versus those found in young infertile patients. Lilli P. Thorsell,Julie Oliver. Genetics & IVF Institute, Fairfax, VA.

Objective: Aneuploidy rates in embryos of infertile patients appear toincrease with maternal age. Most aneuploidies are a result of non-disjunc-tion in the female gamete at meiosis I, so it is advantageous to evaluateoocytes, and complementary first polar bodies if at all possible, to determinethe origin of chromosomal abnormalities. The purpose of this study was tocompare aneuploidy rates in unfertilized oocytes from young fertile donorsto those found in young infertile patients using chromosomes X, Y, 13, 18,and 21. A comparison between fertile and infertile patients helps to deter-mine if aneuploidy is a function of increasing maternal age, or if it is apotential cause of infertility even in younger patients.

Design: Basic research with Independent Review Board (IRB) approvalto use unfertilized oocytes, with patient’s informed consent.

Materials and Methods: Patients with oocytes remaining unfertilized attime of embryo transfer on day 2 were asked to donate the oocytes foraneuploidy testing; those couples who agreed were given an informedconsent to read and complete. A total of 172 oocytes remaining unfertilizedat time of embryo transfer on day 2 were obtained for examination. Indi-vidual oocytes were fixed to glass slides, approximately 48 hours postretrieval and underwent fluorescence in-situ hybridization (FISH) using theVysis™ Multivysion™ PGT probe kit for chromosomes X, Y, 13, 18, and21. Oocytes with clear chromosome spreads and sufficient removal ofooplasm were coded and scored “blindly” for presence of fluorescent signalsfor chromosomes X, 13, 18, and 21, paying particular attention to splitsignals of sister chromatids.

Results: Results could be read in 107 / 172 oocytes yielding an oocytefixation efficiency of 62.2%.

Chi Square analysis showed no statistically significant differences inaneuploidy rates between young fertile “patients” and young infertile pa-tients.

Conclusions: The data shows that young fertile “patients” are not lesslikely to have chromosomal abnormalities with chromosomes 13, 18, 21,and X than young infertile patients; suggesting that the incidence of anom-

FERTILITY & STERILITY� S117