By Gorka Barrenetxea
As usually, the last ESHRE Annual Meeting has been successful both in attendance and scientific level of speakers as well as an opportunity to share experiences and knowledge with colleagues from over the world.
I have been honored with the invitation as a chairman of a scientific session (on biology of oocyte and cumulus complex) and the entire team of Reproducción Bilbao has play an active role by presenting a poster on single embryo transfer policy of our center.
Many topics have been debated but I would like to underline two specific issues of remarkable importance. Let`s go with the first one. The second will be described in a later post. S. Sunkara (from UK) is one of the most cited author in the assisted reproduction field. Her papers on the number of oocytes considered ideal for IVF success constitute a cornerstone regarding ovarian stimulation targets. Her conference on cumulative live births as the optimal end point has been both clear and clarifying. Traditionally, IVF success has been reported as live birth rate per cycle or per transfer. There “were” a non-lineal relationship between number of achieved oocytes and pregnancy rate. Above 14-15 oocytes there was not an improvement in success rates. Thus, there “were” an ideal number of oocytes to be achieved in each egg retrieval (14-15). Besides, the risk of ovarian hyperstimulation syndrome could be considerable among high responder women. So, the end point was to achieve 14-15 oocytes in each procedure.
However, now things are different. In the XXIst century we have witnessed both, huge improvements in cryopreservation technology and advances in controlled ovarian stimulation procedures by the use of GnRH antagonists as adjuvant therapy and agonists as ovulation triggers. Thus, frozen-thawed embryo transfers are performed increasingly. Thus, cumulative live birth rate, defined as live births resulting from one initiated ART cycle (including fresh and frozen embryo transfers), is a more robust outcome measure of success in ART. In this setting, the achievement of as many oocytes as possible is advisable. Whereas the pregnancy rates did not increase once 14-15 oocytes were obtained (when only fresh cycles were assessed), current evidence shows that by combining fresh and frozen-thawed cycles the more oocytes recovered, the higher the chance of having available embryos to be transferred to achieve one or more pregnancies (after only one ovarian puncture).
The key message would be: “Once technology is available, use it” (of course, looking upon patients` safety).