fertilization rate of 44% (89/198) was much lower than the 74.6% rate in1286 MII oocytes (P � 0.0001). Their survival and rates of abnormalfertilization were similar, as was embryonic cleavage (36.7% of 960 forMII, and 34.8% of 89 for MI). Because they were transferred together withembryos derived from MII oocytes, it was not possible to obtain thepregnancy rate for embryos developing from MI stage oocytes.

Conclusion: Of the cycles assessed, 16.7% had at least one MI oocyte atthe time of cumulus cell removal that nevertheless matured within a fourhours period. Although the in-vitro matured MI oocytes exhibited a signif-icantly lower fertilization rate than those at MII, the cleavage patterns ofthose fertilized were similar. Thus, although fertilized at a lower rate, MIoocytes can be successfully injected, they do not reveal a higher incidenceof fertilization abnormality and can be included in the cohort being evalu-ated for embryo cleavage and eventual transfer. However, caution should betaken in including embryos from these recently matured oocytes into thecohort of embryos selected for transfer because in vitro development ofblastocyst and implantation capability of these oocytes need to be furtherelucidated.

Wednesday, October 15, 20034:30 P.M.

O-308

Pre-implantation genetic diagnosis (PGD) for aneuploidy does not sig-nificantly improve chances for conception in an at risk populationundergoing IVF. Glenn L. Schattman, Kang Pu Xu, Steven Spandorfer,Jose Navarro-Pando, Zev Rosenwaks. The NY Presbyterian Hospital/ WeillMedical Coll of Cornell Univ, New York, NY; IVI-Sevilla, IVI, Spain.

Objective: To investigate whether PGD improves cycle outcomes byincreasing pregnancy rates or decreasing miscarriage rates in women at riskfor aneuploidy.

Design: Retrospective analysis of all patients at one major IVF programwho had an IVF retrieval from January 2001 to December 2002 and wantedto have their embryos analyzed for aneuploidy either due to advanced ageor a history of spontaneous miscarriage.

Materials and Methods: Patients who were scheduled to undergo IVF foraneuploidy analysis from 1/2001 to 12/2002 were included in the analysis.Patients who did not have an oocyte retrieval or whose oocytes did notfertilize were excluded from the study. Two groups of patients were eval-uated. Group 1 included patients who did not undergo a biopsy proceduredue to a low number of pre-embryos available for biopsy or due topre-embryos that were developing slowly and therefore not eligible forbiopsy. Group 2 included patients who had all pre-embryos �5 cellsbiopsied on day 3 after retrieval and transferred on day 5.

Results: Eighty four patients (102 cycles) were included in the analysis:34 patients (40 cycles) in group 1 and 50 patients (62 cycles) in group 2.Nine patients in group 2 did not have an embryo transfer procedure. Themean age of the patients was equivalent between the groups; 39.9�2.5 ingroup 1 and 39.5�4.4 in group 2. There was also no difference in the meannumber of oocytes retrieved between the two groups respectively, 12.2�6.4and 13.1�5.3. Fertilization rates were higher in the group that underwentpre-embryo biopsy leading to a greater number of 2PN pre-embryos ingroup 2 (8.9�3.7) compared to group 1 (6.8�3.7) (P � 0.0063). Thepregnancy rate per transfer was 57.5% in group 1 and 45.3% in group 2, notstatistically different (P � 0.063). Miscarriage rate was higher in group 1(48%) compared to group 2 (33%) leading to an ongoing/delivered preg-nancy rate per retrieval of 30% in group 1 and 33.9% in group 2 (N.S.).Implantation rates were also higher in group 1 (24.3% sacs/blastocysttransfer) compared to group 2 (19.5% sacs/embryo transfer) but this differ-ence was also not significant.

Conclusion: Pre-implantation genetic diagnosis is being utilized morefrequently for a number of disorders. The lower implantation and pregnancyrate in older patients is mainly due to an increase in aneuploidy in olderwomen. In an effort to improve chances for conception and lower miscar-riage risks, PGD can screen out embryos with the most common chromo-somal defects before transfer. Our results show that the limited geneticscreening reduces the chances for miscarriage, but overall pregnancy ratesare not significantly improved with this approach.

Key Words: In vitro fertilization, Pre-implantation genetic diagnosis,Aneuploidy.

Wednesday, October 15, 20034:45 P.M.

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Effect of karyotype and cell number on blastocyst development follow-ing day 3 biopsy. John M. Stevens, William B. Schoolcraft, Mary Rawlins,David K. Gardner, Santiago Munne. Colorado Ctr for Reproductive Med-icine, Englewood, CO; The Institute for Reproductive Medicine of SaintBarnabus, West Orange, NJ.

Objective: Blastomere biopsy and FISH analysis of aneuploidy enablesthe determination of the relationship between blastocyst formation andchromosomal abnormalities. In addition by culturing embryos individually,it is possible to track the development of each embryo.

Design: A retrospective analysis of 31 IVF cycles with PGD for aneu-ploidy. Blastocyst development of individual embryos was tracked based onchromosomal abnormality and day 3 cell number.

Materials and Methods: 358 embryos from 31 IVF cycles were biopsiedon day 3 of culture. Each embryo had one cell removed. Cells were fixed onslides and analyzed using Fluorescent In-Situ Hybridization (FISH) foraneuploidy. 8 different chromosomes were routinely tested. X, Y, 13, 15,16, 17, 18, 21 and 22. In some cases, additional chromosomes wereanalyzed depending upon the patient’s history.

Results: Of the 358 embryos biopsied, results were obtained on 316(88%). 27% of the embryos were diagnosed as normal and 68.5% (61/89) ofthese embryos formed blastocysts. Monosomy 16 was the most commonabnormality at 9.6% (27/282), 54% of such embryos reached the blastocyststage. Embryos diagnosed as monosomies of X or Y, 13, 15, 21 and 22 werealso capable of forming blastocysts, while monosomy 17 or 18 alwaysarrested. Trisomy 21 was the next most common abnormality at 7.7%, with86% of such embryos forming blastocysts, as did Trisomy 18 (80%), andTrisomy 22 (78%). Trisomy 13 and trisomy 16 were also not inconsistentwith blastocyst development. Biopsied embryos which started as 3 cells onday 3 did not form blastocysts. 23 % of 4 cell embryos made blastocysts (4of 43 were normal, 1 baby was born). 15 % of 5 cell embryos madeblastocysts, 39 % of 6 cell embryos made blastocysts, 48 % of 7 cellembryos made blastocysts and 62 % of 8 cell embryos made blastocysts.

Conclusion: Studies have shown that monosomic embryos from chromo-somes other than X, Y and 21 do not reach blastocyst stage. Should thesemonosomic embryos make good quality blastocysts, then the monosomicdiagnosis could be either an error and the embryo are normal or trisomic forthe chromosome in question or the embryo could be mosaic with bothnormal and abnormal cells. Embryos diagnosed as monosomic which makegood blastocysts could be considered for transfer or freezing if no othernormal embryos are available. The chromosome in question in these em-bryos must be considered inconclusive and could be normal or trisomic andthe patient counseled accordingly. As monosomy 16 was seen to be the mostcommon diagnosed abnormality, but also made 54% blastocysts, it ispossible that monosomy 16 is the most common misdiagnosis. Trisomicembryos all seem to make blastocysts to some degree and are more unlikelyto be misdiagnosised than monosomies. PGD is a valuable procedure inreducing the risks of transferring abnormal trisomic embryos. Embryos withmore cells on day 3 are more likely to form blastocysts by day 5. Signifi-cantly, embryos with as few as 4 cells on day 3 can form normal blastocyststhat can go to term successfully.

Wednesday, October 15, 20035:00 P.M.

O-310

Fertilization, embryo development, and chromosomal status after in-tracytoplasmic sperm injection of metaphase I human oocytes. Amy E.Jones, Tyl Taylor, Graham W. Wright, Hilton I. Kort, Joe B. Massey, ZsoltP. Nagy. Reproductive Biology Assoc, Atlanta, GA.

Objectives: The recovery of immature human oocytes is a commonoccurrence in routine IVF. The effect of artificially removing a germinalvesicle (GV) or Metaphase I (MI) stage oocyte from its follicular environ-ment is largely unknown, but potential damage to cell cycle regulatorymechanisms is likely. Here, we assessed chromosomal status of the embryos

FERTILITY & STERILITY� S119

that developed from MI oocytes which had undergone ICSI within fourhours post egg retrieval.

Design: A prospective observational study involving 69 ICSI-IVF cycles.Fertilization, embryo development and chromosome status of microinjectedMI ooctes was assessed by fluorescent in situ hybridization (FISH).

Materials and Methods: Oocytes were exposed to hyaluronidase for 1minute immediately following egg retrieval and returned to culture. Afterthirty minutes coronal cells were removed, and oocytes were assessed formaturity. Intracytoplasmic sperm injection (ICSI) was carried out on all MIoocytes within 3-6 hours post egg retrieval, and all MI injected and fertilizedeggs were cultured separately. Seventy-two hours post egg retrieval, em-bryos derived from MI injected oocytes were scored and reserved forblastocyst culture if they were at least 6 cells and had less than 20%fragmentation. Embryos which did not meet blastocyst culture criteriaunderwent zona removal, disaggregation and fixation. Five color fluorescentin situ hybridization (FISH) for chromosomes X,Y,13,18,21 was latercarried out for aneuploidy assessment of the fixed cells.

Results: One hundred and eighteen MI oocytes underwent ICSI and 31 ofthem displayed 2PN (26.5%), 2 of them showed 1PN, 4 showed 3PN and 81

eggs did not display any pronuclei. Sixteen embryos (that had 2PN fertili-zation) were fixed and results were obtained on fifteen. A total of 93 cellswere fixed, of which 60 (66.6%) provided results. Nine cells that were fixedwere multinucleated (15%). Only one embryo had a normal chromosomalcontent, while the remaining fourteen embryos were chaotic mosaics.

Conclusion: The results of the present study indicate that ICSI of MIoocytes not only results in a lower than normal fertilization rate, but alsoproduces a very high proportion of chromosomally abnormal early cleavageembryos. It may be hypothesized that premature activation of an oocytewhich has not completed meiosis I may alter cell cycle regulatory pathwaysand checkpoints which are responsible for preventing further cleavage anddevelopment of an abnormal cell. Moreover, the presence of the spermcentrosome prior to completion of meiosis I may alter the bipolarity of thefirst meiotic spindle resulting in an abnormal separation of the homologueswhich will consequently lead to a chaotic mosaic embryo, as it was observedin our study. These results indicate that ICSI of MI oocytes should not beused for clinical purposes. However, it may be an important model to studytiming of oocyte activation and spindle modifications.

S120 Abstracts Vol. 80, Suppl. 3, September 2003