RESULTS:639 d 5 transfers were performed. In the post-SBT-P period, 64% (183/285) of transfers were mandated single embryo transfers. Pa- tients qualifying for SBT had a fresh transfer ongoing PR of 70% and 85% cumulative fresh and frozen transfer ongoing PR. Implementation of the SBT-P mandate reduced the incidence of multifetal gestation by 70% (Table). CONCLUSIONS: A single embryo transfer mandate for good prognosis patients improved cycle outcomes by maintaining PR and increasing the singleton gestation rate/transfer. Over half the d 5 transfers were affected by this program shift, proving the vital potential for similar policies across the country. Supported by: None. Wednesday, October 17, 2007 3:45 pm O-273 RELATIONSHIP BETWEEN EMBRYO MORPHOLOGY AND CHROMOSOMAL ABNORMALITIES: COMPARISON BETWEEN IN VITRO FERTILIZATION (IVF) AND INTRA-CYTOPLASMIC SPERM INJECTION (ICSI) CYCLES. S. P. Kang, S.-P. Weng, D. L. Hill, M. W. Surrey, H. C. Danzer, T.-C. J. Wu. Obstetrics and Gynecol- ogy, REI, David Geffen School of Medicine at UCLA, Los Angeles, CA; ART Reproductive Center, Beverly Hills, CA. OBJECTIVE: To study the incidence of chromosomal abnormalities in embryos derived from IVF and ICSI in relation to embryo stages and grading. DESIGN: Retrospective data analysis. MATERIALS AND METHODS: Male infertility requiring ICSI who also had PGD were included in the study. Patients with IVF and PGD served as controls. PGD was performed by FISH using 5 chromosome probes. Additional 8 chromosomes were examined if indicated. Abnormal chromosome patterns included haploidy, polyploidy, aneuploidy and com- plex chromosomal abnormality which involved 3 or more chromosomes with abnormal copies. Each embryo was scored by cell number and grades (A-D). Statistical analyses were performed using t test, chi square and Fisher’s exact tests. RESULTS: A total of 460 embryos from 101 cycles of ICSI and 1119 embryos from 155 cycles of IVF were analyzed. Overall rates of normal chromosomes for embryos derived from ICSI and IVF were 48.9% vs. 48.2%, respectively (P¼0.79). For IVF cycles, embryos that were 7–8 cells had the highest rate of euploidy (60%) as compared to embryos >8 cells (52%) or <7 cells (26%) (P¼0.000). ICSI cycles showed the same correlation [Fig1]. There were no differences in the euploidy rate between odd and even number of cells in both ICSI and IVF cycles. The rates of euploidy for IVF cycles decreased with poor grading scores: 65, 49, 22, and 14% for grade A, B, C, and D, respectively. There was no difference between ICSI and IVF groups [Fig2]. Figure 1. CONCLUSIONS: Embryos at 7–8 cell stage have the highest rate of nor- mal chromosomes. Up to 74% of embryos <7 cells are chromosomally ab- normal. There is an excellent correlation between embryo grading and the rate of euploidy. Grade A embryos are three times more likely to be chromo- somally normal as compared to grade C or D embryos. ICSI procedure doesn’t appear to have impact on the relationship between embryo morphol- ogy and chromosomal patterns. Supported by: None. Wednesday, October 17, 2007 4:00 pm O-274 THE ‘AFTERLOAD’ METHOD OF EMBRYO TRANSFER COR- RECTS FOR PROVIDER-DEPENDENT EFFECTS AT ET. B. J. Stegmann, M. Payson, A. DeCherney, J. Segars. Reproductive Biology and Medicine Branch, NICHD/NIH, Bethesda, MD; Walter Reed Army Medical Center ART Program, Washington, DC. OBJECTIVE: We have previously reported that more experienced pro- viders had superior outcome following ET when a direct insertion method of embryo transfer was used (Hearns-Stokes et al, Fert Steril 2000). More re- cently, we reported on a modified method of embyo transfer, the ‘afterload’ method, that appears to require less experience to master (Neithardt et al, Fert Steril, 2005). The objective of this study was to compare ET outcome vari- ables between inexperienced and experienced providers using the ‘afterload’ method. DESIGN: Retrospective cohort analysis. MATERIALS AND METHODS: The cohort consisted of all women un- dergoing day 3 embryo transfer after fresh IVF/ICSI cycles at Walter Reed Army Medical Center ART program from July 2003 to Dec 2006. The num- ber and grade of the embryos was recorded. All transfers were done with a Wallace catheter using the ‘afterload’ technique under ultrasound guidance as previously described. Pregnancy rate was calculated based on the day 16 HCG level. Implantation rate (# of sacs/# of embryos transferred) was calcu- lated using the 6 week ultrasound. Chi-squared and student t-test were used as appropriate. Regression analysis was used to analyze implantation and pregnancy data while adjusting for the number of high grade embryos. Fel- low trainees were considered inexperienced providers and attending staff were considered experienced providers. RESULTS: A total of 1,277 transfers were performed, 863 for attendings and 414 for fellows. 2,989 embryos were transferred of which 1608 (54%) were high grade. There was no difference in the number of high grade em- bryos transferred by attendings vs. fellows (1.28/transfer vs. 1.22/transfer, re- spectively). Pregnancy rate and implantation rates were similar between the two groups after adjusting for high grade embryos. Attendings had a preg- nancy rate of 59% and an implantation rate of 0.32, while fellows had a preg- nancy rate of 56% and an implantation rate of 0.30, (P¼0.433 and 0.45, respectively). Figure 2. FERTILITY & STERILITY Ò S103