Does intentional endometrial curettage before embryo transfer increases the chances of successful outcome?

Clinical pearls:

• Current research points in favor of performing endometrial scratching between day 7 of previous cycle to day 7 of the embryo transfer cycle resulting in improvement in clinical pregnancy rate and live birth rates in women with more than two previous embryo transfers. 

It is proposed that endometrial scratching or biopsy increases the chances of implantation in women attempting ARTs. With an intention to determine the current practice clinicians across Australia, New Zealand and the UK were given an on-line survey between August to October 2015.  The results of this study was published in the recent issue of Human Reproduction.[1]

In this cross- sectional study spanning 143 private and public fertility centers, 89% of physicians, embryologists and nurses perform the endometrial biopsy or scratching as a part of treatment protocols for couples undergoing IVF.[2]

The most common indication (92%) for the procedure was Recurrent Implantation failure (RIF) while only 3.6% clinicians offered it to patients trying to conceive by natural intercourse or IUI. Although many trials exist documenting the benefit of this procedure in couple trying to conceive naturally. [3]  

It was interesting to see that they all followed different time frame for doing the procedure.

89% of the centers offered the procedure in the luteal phase of the cycle prior to the embryo transfer cycle and none performed it on the day of egg retrieval or embryo-transfer.  

Two- thirds of the responders agreed that it is very useful in RIF undergoing IVF and more than 50% did not think it to be useful before the first IVF cycle.

Currently the most accepted explanation for the success is favorable immune modulation of the endometrium increasing the implantation rate. Other theories are it modulates the gene expression and increases the receptivity. [4]

A review of literature finds many RCTs conducted in the past to gauge the benefit of the procedure.

Results of Cochrane systemic review of 14 Randomized control trial(RCTs) shows that endometrial injury before starting the ovarian stimulation improves the chances of conception and ongoing pregnancy.[5] The evidence is moderate grade and suggests that “Endometrial injury performed between day 7 of the previous cycle and day 7 of the embryo transfer (ET) cycle is associated with an improvement in live birth and clinical pregnancy rates in women with more than two previous embryo transfers.”

With all these evidence pointing in favor of the procedure, a very large and robust study with sufficient power by Yeung et al[6] published in Human Reproduction showed that the procedure does not offer any benefits contrary to the previous beliefs. But, in this study about 70% of the patients received the procedure in their first IVF cycle so the results may not be generalized to patients with RIF.

To conclude, although current evidence is in favor of endometrial scratching, more evidence is needed in the form of large, randomized clinical trials regarding its timing in relation to menstrual cycle, use in women with or without RIF and its use in natural cycles, before this inexpensive and simple procedure can be widely applied in fertility clinics.

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[1] http://humrep.oxfordjournals.org/content/31/6/1241.abstract

[2] http://humrep.oxfordjournals.org/content/31/6/1241.full.pdf+html

[3] Gibreel A, Badawy A, El-Refai W, El-Adawi N. Endometrial scratching to improve pregnancy rate in couples with unexplained subfertility: a randomized controlled trial. J Obstet Gynaecol Res 2013;39:680 – 684.

[4] Zhou L,Li R, Wang R, Huang H-x, Zhong K. Local injury to the endometrium in controlled ovarian hyperstimulation cycles improves implantation rates. Fertil Steril2008;89:1166-1176.

[5] http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD009517.pub3/pdf

[6] http://humrep.oxfordjournals.org/content/29/11/2474.full