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, a procedure performed before in vitro fertilization (IVF) that was thought to increase IVF success rates, had no impact on live birth rates, a randomized trial found.

Women undergoing IVF who were randomized to endometrial scratch by pipelle biopsy had no significant improvement in live birth rates or pregnancy rates of any kind compared with women who were randomized to no procedure, reported Sara Lensen, MD, of the University of Auckland in New Zealand, at the (ESHRE) annual meeting in Barcelona.

"Results from earlier studies have suggested a benefit from endometrial scratching in IVF, especially in women with previous implantation failure," Lensen said in a statement. "However, many of these studies had a high risk of bias in their design or conduct and did not provide strong evidence. There was still uncertainty about the validity of a beneficial effect."

In 2016, Lensen's group presented a review of the research indicating that endometrial scratch was associated with an almost twofold increase in the probability of clinical pregnancy when compared with "mock" scratching or no scratching. But even back then, they warned that most randomized trials had a serious risk of bias.

So they undertook a larger pragmatic randomized trial of their own that was comprised of 13 fertility centers in five countries that involved more than 1,300 women undergoing IVF. 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."

Those in the endometrial scratch group had the procedure done between day 3 of the preceding cycle and day 3 of the IVF/embryo transfer cycle. There were 690 women randomized to endometrial scratch and 674 to control.

In an intent-to-treat analysis, the rates of live birth were identical -- about 26% apiece in both groups, and there was no difference between groups in the rates of biochemical pregnancy, ectopic pregnancy, ongoing pregnancy, clinical pregnancy, or multiple pregnancy.

The study also examined pain and adverse events related to endometrial scratching, and found the median pain score was 3.5, and there were 14 adverse events related to the procedure. Seven were vasovagal reactions, five were excessive pain, and two were excessive bleeding.

Given these adverse events, as well as little evidence of benefit, Larsen recommended fertility clinics "reconsider" the IVF adjuvant procedure.

"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. "Nevertheless, even based just on our results, I think clinics should now reconsider offering endometrial scratch as an adjuvant treatment."