Highlights from PCRS 2015: Study Suggests ICSI Does Not Increase the Risk of Aneuploidy
At the recent 2015 Pacific Coast Reproductive Society (PCRS) meeting, three papers received the PCRS Allied Health Professional Award, which recognizes outstanding presentation in specialties such as reproductive endocrinology, urology, gynecology, nursing, and genetics.
1 an abnormal number of chromosomes. In most cases, aneuploid embryos do not implant or they result in early miscarriage. Down syndrome (Trisomy 21) is a rare example of aneuploidy that can result in a live birth.
What is ICSI?
Introduced in 1992, ICSI is an IVF procedure where a single sperm is injected directly into an egg. ICSI is used for:
- Male factor infertility
- Certain female factors such as a limited number of oocytes or abnormalities in the oocyte or its surrounding membrane (zona pellucida)
- An IVF cycle if poor fertilization or fertilization by more than one sperm occurred previously with insemination
- Preimplantation genetic diagnosis (PGD), especially for single gene defects2
Previous studies had suggested that ICSI increased the risk of aneuploidy in offspring, but the underlying reason remained unclear. Was it due to selection of sub-optimal sperm or to the invasive nature of ICSI itself?
In this study, researchers dug a little deeper to learn more.
Controlling for maternal age, they assessed the rate of aneuploidy in 3,306 embryos at Oregon Reproductive Medicine in Portland, OR, using comprehensive chromosome screening (CCS) in four groups of patients undergoing:
- Standard in vitro fertilization (IVF) without ICSI
- IVF-ICSI with normal semen
- IVF-ICSI with mild male factor infertility
- IVF-ICSI with severe male factor infertility
As expected, advanced maternal age produced a significant increase in aneuploidy. The researchers observed an even greater increase in the rate of aneuploidy in patients undergoing ICSI for severe male factor, where it was more than double the rate for those undergoing standard IVF, as well as those undergoing ICSI with normal sperm or mild male factor infertility. However, aneuploidy was limited to that involving sex chromosomes, which produces milder effects than autosomal aneuploidy.
When controlling for age, the researchers found no significant difference in the rate of aneuploidy between the four treatment groups, and concluded that ICSI appears to be safe. However, they recommend CCS to selectively transfer embryos with the correct number of chromosomes (euploid embryos) in men with severe male factor infertility.