SANTA BARBARA, CALIF. – Routine comprehensive chromosomal screening so improves implantation rates that it makes single embryo transfer a realistic and highly cost-efficient procedure for couples undergoing in vitro fertilization, according to Dr. Richard T. Scott Jr.
In a randomized clinical trial, comprehensive chromosome screening led to successful implantation in 54 of 71 cycles (a 76.1% implantation rate), compared with 42 of 81 cycles (51.8%) in those treated in a standard fashion at Reproductive Medicine Associates of New Jersey, Morristown, the clinical center serving the division of reproductive endocrinology at the Robert Wood Johnson Medical School. Dr. Scott serves as professor and director of the division, and as clinical and scientific director of the medical group.
A 4-hour polymerase chain reaction (PCR) screening assay chromosome screen resulted in a delivery rate of 87.2% (34 of 39 patients), compared with a control rate of 68.3% (28 of 41) in a randomized trial conducted at his center, reported Dr. Scott at the conference on in vitro fertilization and embryo transfer, which was sponsored by the University of California, Los Angeles.
By upping the odds of a successful implantation and delivery, routine chromosome screening may one day outpace aneuploidy screening as the method of choice for selecting prime candidates for transfer, Dr. Scott predicted.
Indeed, his group has challenged the accuracy of aneuploidy screening, suggesting that it results in a high rate of false aneuploid results, thus lowering the transfer rate of embryos that might result in healthy infants. Along the way, the temptation builds to implant more than one embryo, despite the risks inherent in twin or higher-order multiple pregnancies, he said.
"It’s mathematically impossible for one to be as good as two," he said. "The gain approaches 25%. The bottom line is, it’s always tempting."
Dr. Scott said that the results from using comprehensive chromosomal screening for embryo selection are so superior that they might override that temptation, resulting in healthier singleton pregnancies at a reasonable cost to patients.
"I think it’s safe to say one screened embryo does as well or better than two unscreened embryos," he said. "The question is, is it cost effective?"
Answering his own question, Dr. Scott asserted, "It’s overwhelmingly and amazingly cost effective."
The cost of a singleton pregnancy, delivery, and newborn care following comprehensive chromosomal screening and IVF vs. aneuploidy screening and IVF followed by a twin pregnancy saves $1.8 million per 100 patients, or $18,700 per patient, he estimated.
The cost of infertility treatment in such an equation basically costs out at zero for couples who decide to transfer only one chromosomally selected embryo, said Dr. Scott.
The chance of abnormal gestations following comprehensive chromosomal screening is "not zero, but awfully low," he reported.
Specifically, Dr. Scott’s clinic’s clinical error rate was 0.2% in over 3,500 screened euploid embryos transferred, in more than 2,400 clinical implantations.
When products of conception were subjected to DNA fingerprinting to establish embryo origins, five abnormal gestations were traced to the procedure, including one diagnostic error (a tetraploid embryo), one trisomy 13, one Turner’s syndrome, one trisomy 21, and one healthy baby born with the opposite gender than what was predicted, through a lab error.
Dr. Scott reported that he receives grant research support and is on the speakers bureau and the scientific advisory board for EMD Serono and Ferring Pharmaceuticals. He also receives grant research support and is on the speakers bureau for Merck.