If you’ve been unsure who to believe about fertility treatment add-ons, you may be interested in some impartial and expert advice in two new scientific opinion papers published by the Royal College of Obstetricians and Gynaecologists (RCOG). They call for more high quality research into the role of natural killer cells in fertility and the effect of endometrial scratching on pregnancy outcomes.
Scientific Impact Papers (SIP), are up-to-date reviews of emerging or controversial scientific issues. The first paper looks at the role of uterine natural killer (uNK) cells, how they are measured, the role of testing and the evidence behind any links to improving implantation rates and early placental development. The paper clarifies that uNK cells are completely different from peripheral blood natural killer cells (which you would be testing in the blood tests some fertility clinics currently offer).
The paper makes it clear that there is no evidence to offer routine tests for NK cells as part of fertility treatment or testing, and that there is uncertainty about how NK cells are measured and reported. The paper says that treatment for raised levels with intravenous immunoglobulin (IVIg) is not supported by the current evidence and, since it may have serious adverse effects, should not be used..
The second opinion paper explores the effect of endometrial scratch on pregnancy outcomes in women who have experienced recurrent miscarriage and recurrent implantation failure.
Endometrial scratch is a procedure which is hypothesised to help embryos implant more successfully after IVF/ICSI and involves scratching the lining of the womb.
Several studies have examined the impact of endometrial scratch in the cycle preceding an IVF treatment cycle in women with recurrent implantation failure, which appear to provide convincing evidence of benefit of superficial endometrial scratch in improving the implantation rate in this group of women. However, the effect of this treatment on pregnancy outcomes in women who have experienced recurrent miscarriage or those undergoing their first IVF cycle is uncertain.
Professor Adam Balen, Chair of the British Fertility Society (BFS) and spokesperson for the RCOG, said: “These two papers look at the current available evidence which exists and give much-needed guidance to both healthcare professionals and the public on these two topics. It is important that patients receive full information about treatments, the current evidence for benefit and whether there are any side effects or risks associated with it.”
Mr Mostafa Metwally, Vice Chair of the RCOG’s Scientific Advisory Committee added: “There is currently no convincing evidence that uterine natural killer cells are the cause of reproductive failure. Despite this, a number of women are requesting and being offered analysis of either peripheral blood or uterine killer cells and the value of these measurements remains controversial. Current evidence suggests that endometrial scratch may benefit women with recurrent implantation failure and therefore defining the optimal number of previously failed embryo transfer cycles needs to be evaluated in large cohort randomised prospective clinical trials.We still do not understand the mechanism by which endometrial trauma may lead to improvements in IVF outcomes in women and further studies are needed looking specifically at its success among women undergoing their first IVF cycle.”
The papers are available here:
The Role of Natural Killer Cells in Human Fertility
Local Endometrial Trauma (Endometrial Scratch): A Treatment Strategy to Improve Implantation Rates