Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. The Cochrane Gynaecology and Fertility Group had produced approximately 100 reviews relevant to in vitro fertilisation, or IVF and updates these in light of new evidence. The second update of their review of a technique called endometrial scratching was published in June 2021 and, in this podcast, Dr Rob Axe speaks with one of the authors Dr Sarah Armstrong, from the University of Sheffield in the UK about the technique and their latest findings on its effects.

Rob: Hello Sarah, thanks for speaking to us about this Cochrane review which focuses on the effectiveness and safety of endometrial scratching, also known as endometrial injury, before IVF or ICSI.

Sarah: No problem, it's my pleasure!

Rob: Please could you explain what endometrial scratching is, and why it's sometimes used in IVF?

Sarah: There are three main theories behind why scratching might help a woman to become pregnant. The first is that the scratch could cause the endometrium, which is the lining of the womb, to mature to be at the optimal state ready to receive an embryo. The second is that it induces a wound healing response which is beneficial to implantation of the embryo, and the third is that it helps sync the endometrium to be at the right stage to receive an embryo.

Rob: So why is it important to have a review of its effectiveness in women undergoing IVF?

Sarah: Two reasons really - firstly, there are lots of studies published on this, and a lot of them have conflicting results. It's helpful to have a reliable summary of the evidence which has taken into account the various biases of the individual studies and assessed the reliability of results. Secondly, for women, endometrial scratching is an invasive procedure, which is commonly offered to women during IVF treatment at an additional cost, and it's important that there is a freely accessible and scientific answer to the question of whether scratching is effective.

Rob: Did you find the evidence you needed and what does it say about endometrial scratching for women undergoing IVF?

Sarah: The review certainly uncovered lots of randomised trials that studied endometrial scratching - 37 in total. There was a great deal of heterogeneity between the studies when we combined them, which made the results very difficult to interpret, and therefore we decided to restrict the analysis to studies at low risk of bias. The findings of the review showed that endometrial scratching was no better or worse than not scratching the lining of the womb when looking at livebirth, or clinical pregnancy. The quality of the evidence was moderate. 

Rob: What about the safety aspect? What did you find?

Sarah: We looked at miscarriage as a measure for safety and we found that scratching doesn't appear to affect the chance of miscarriage. However, it revealed that women in the studies found scratching to be a somewhat painful procedure associated with a small amount of bleeding.

Rob: In a nutshell, what is the take-home message about endometrial scratching?

Sarah: Current evidence does not support the routine use of endometrial injury for women undergoing IVF. 

Rob: Thanks Sarah! If people want to get hold of the review, where can they find it?

Sarah: If you google 'Cochrane endometrial scratch' you can find it, or go to cochranelibrary.com and type in 'endometrial scratch' to the search box. Reviews are free to access across the world.