No benefit to endometrial scratching pre-IVF: Is it time to abandon practice?
Endometrial scratching prior to in vitro fertilization (IVF) failed to improve live birth rates in the PIP* study, challenging a practice currently embraced by gynaecologists to boost the chances of embryo implantation in subfertile women.
Scratching the uterine lining apparently disrupts the endometrium, inducing an inflammatory response that promotes repair or wound healing reaction which then improves the endometrial architecture and makes it suitable for embryo implantation and pregnancy. However, the biological process behind this procedure remains unclear and fertility experts are still locked up in debates as to the merits of performing an endometrial scratch.
Dr Sara Lensen from the University of Auckland in Auckland, New Zealand and her team sought to investigate whether endometrial scratching by pipelle biopsy increases live birth rates in women undergoing IVF. The trial included 1,300 subfertile women from 13 centres across five countries, who were randomized to endometrial scratching (n=690) vs no procedure (n=674). The study was conducted between June 2014 and June 2017. Women were eligible if they were undergoing fresh or frozen embryo transfer of their own oocytes and had no recent exposure to disruptive intrauterine instrumentation. Endometrial scratch was done between day 3 of the preceding cycle and day 3 of the IVF/embryo transfer cycle. Sample-size was calculated separately in women who had ≥2 unsuccessful embryo transfers, and those who had not tried IVF. [ESHRE 2018, abstract O139]
Live birth rates comparable at 26 percent
At study end, endometrial scratching pre-IVF did not improve live birth or pregnancy rates, said Lensen. In the intent-to-treat analysis, the live birth rates were similar in both groups at 26 percent. The effect remained similar after adjusting for protocol deviations and despite observation that fewer women in the control arm underwent an embryo transfer. There was also no difference in the rates of biochemical pregnancy, ectopic pregnancy, ongoing pregnancy, clinical pregnancy, or multiple pregnancy between groups.
There was also no evidence of benefit either in women with recurrent implantation failure or those undergoing fresh or frozen cycles, and despite different timings of scratching. Median pain score related to endometrial scratching was 3.5. Fourteen procedure-related adverse events were reported – vasovagal reactions (7), excessive pain (5), and excessive bleeding (2).
Previous studies have suggested a benefit from endometrial scratching prior to IVF, but many of these studies had a high risk of bias and only provided weak evidence, noted Lensen. “There remains an uncertainty as to the beneficial effect.”
New evidence casts doubt on the technique
Given the adverse events and the little-to-no evidence of benefit in the current study, Larsen said fertility clinics should “reconsider” endometrial scratch prior to IVF. “Our results contradict those of many studies published previously, and although our trial was the largest and most robust study undertaken so far, it can be difficult for one trial to change practice,” she said. “However, I still think clinics should reconsider offering endometrial scratch as an adjuvant treatment.”
The procedure is similar to performing an embryo transfer and done by inserting a catheter through the cervix and to the uterine lining which may cause mild pain similar to period pain.