Please don't google "endometrial scratch." Ok, you probably just opened a new browser window and googled it. That's certainly how I roll when told not do so something. haha....
The lining of the uterus is called the endometrium. It is the part of the uterus that grows each month (in most women) and then shed. When it sheds, that's your period. Now, it does not completely shed - only the top 90%. The bottom 10% stays there forever and then makes the upper 90% each month. The endometrium is where an embryo sticks/implants. It's one of the most important structures in fertility. Endometrial scratch is when a doctor puts a tube inside the uterus and scratches the lining - scrapes off part of the upper 90% of the lining.
When any part of the body is scratched, scraped or injured it heals. Hopefully it heals better than before. Dermatologists take advantage of this process on the skin. They will burn/laser/scrape off the top layer of the face and hope it heals more youthfully. I've had my face lasered a few times (IPL) with the hopes of having heathier, younger looking skin and, in me, I think it works a little bit. There is a risk that it could make the skin or other tissues worse but most of the time it seems to help.
About 15 years ago a group of Israeli researchers did three scratches in the menstural cycle and then examined pregnancy rates during the IVF cycle, which occured one month later. They found an improvement in pregnancy rates (Barash A, et al. Local injury to the endometrium doubles the incidence of successful pregnancies in patients undergoing in vitro fertilization. Fertil Steril. 2003 Jun;79(6):1317-22.) This work generated a lot of buzz. We even did a small study on the topic about 8 years ago. Several other groups did studies asking the same question: does endometrial scratch improve IVF outcomes?
Every study found something a little different for first time IVF cycles. Having reviewd these studies I think we can conclude that there is no good evidence to say it helps. Now, there is evidence though that endometrial scratch helps in those with repeated implantation failure, which is defined as 2 or more failed IVF embryo transfers.
This past month review of all studies on this topic concluded that endometrial scratch injury "may improve IVF success in patient with two or more previous embryo transfer failures undergoing fresh embry transfer. " The most benefit occured when two scratches were performed 2-7 days apart in the luteal phase (second half) of the menstrual cycle. There was no benefit in those women undergoing frozen embryo transfer. This might seem like a tricky problem to sort out - fresh has a benefit but frozen not. The catch, which so often occurs, is that we don't have a lot of good data on women undergoing frozen embryo transfer. (Reference: Vitagliano A, et al. Endometrial scratch injury for women with one or more previous failed embryo transfers: a systematic review and meta-analysis of randomized controlled trials. Fertil Steril. 2018 Sep;110(4):687-702).
What's the compromise? What are we doing at Olive to keep up with this research? We mostly do frozen embryo transfers (about 75% of all of our transfers in the past 12 months). Most patients with two or more failed embryo transfers will be offered endometrial receptivity testing. In this testing we take a biopsy (done the same was as a scratch) to determine if the lining is receptive. It is done in the (usually medicated) luteal phase. Then in the cycle or two following the scratch/biopsy the frozen embryo transfer is done. We think we are then getting endometrial data from the receptivity testing and still potentially giving our patients the benefit of a scratch at the same time.
What about patients trying to conceive who are NOT doing IVF? That research is messy, honestly. There are as many trials suggesting a benefit before treatments like FSH injections for superovulation as there are trials suggesting no benefit. That's why you need to lean on your doctor to (a) know what the research shows currently, and (b) implement what makes sense for your unique case. If not, you'll end up googling yourself crazy.
Ask us. It's our job.