In this guest blog, Sarah Lensen, one of the team who worked on the Cochrane review on endometrial scratching (womb scratching), explains what the latest evidence tells us and what we still don’t know.
Are you having trouble getting pregnant?
As many as 10% of couples experience subfertility, which is defined as the failure to conceive after at least one year of trying for a baby. You might have read in the newspaper recently about a new procedure called endometrial scratching. Some sources have suggested that this procedure can double the chances of getting pregnant. So what is endometrial scratching exactly, and does it really work?
There are a number of different reasons why some couples have difficulty conceiving. Assisted conception methods are available to help these couples get pregnant. These include simple methods such as medication to assist with ovulation, and insertion of sperm directly into the womb, also known as intrauterine insemination (IUI). In vitro fertilisation (IVF) is a more complicated process involving the collection of sperm and eggs for fertilisation in the laboratory, before transfer of an embryo directly into the womb.
Endometrial scratching is currently being suggested as a procedure to increase the probability of pregnancy in women undergoing IVF, but the use of this procedure is still debated. We did a Cochrane review to assess the effect of endometrial scratching on the chance of getting pregnant in women or couples trying to conceive naturally through intercourse or from IUI. Cochrane reviews are internationally recognised as the highest standard of assessing healthcare interventions. They are a way of bringing together the results from multiple separate trials in an unbiased way.
What is endometrial scratching?
The endometrium is a layer of tissue that lines the inside of the womb. In the first step of a pregnancy, an embryo will attach to the endometrium in a process called implantation. Endometrial scratching, also known as endometrial injury, is a procedure undertaken to purposely disrupt the endometrium in women wanting to get pregnant. It is thought this disruption may somehow increase the chance of an embryo implanting, and therefore creating a pregnancy.
Endometrial scratching can be done with many different instruments. The most common technique is the endometrial biopsy procedure, normally done with a thin flexible plastic tube, 3mm wide, called a pipelle catheter. The pipelle is inserted through the cervix (neck of the womb) into the womb, where it is moved back and forth and rotated in order to cause some disruption. This is the very same procedure a gynaecologist would use in order to get an endometrial sample for analysis, where it is called an endometrial biopsy. The procedure has been re-purposed and re-named as endometrial scratching recently due to its potential use in the fertility area. It is a simple, low-cost procedure which can be done at an outpatient appointment, without anaesthetic, in just a few minutes. It can cause some discomfort or pain. Risks of endometrial scratching include infection and uterine perforation, but these are very rare.
How might it work?
It is not clear what the biological process is that may lead to an increased probability of pregnancy. One theory is that endometrial scratching causes some sort of inflammatory response within the endometrium, similar to a scratch on any other part of the body. It may be that the wound healing response following the scratch improves the environment of the endometrium and makes it more likely for an embryo to implant and create a pregnancy.
The evidence for endometrial scratching
Our Cochrane review only included randomised trials about endometrial scratching in women trying to get pregnant from intercourse or IUI. The evidence for endometrial scratching before IVF is the topic of another review.
Our review included nine randomised controlled trials with 1512 women in total. Most women had a type of subfertility known as unexplained subfertility, which means that after having all routine tests done there is no obvious explanation for why the couple has not become pregnant so far.
Overall the results suggest a benefit from endometrial scratching. However, the studies have significant limitations and so the results may be biased. Therefore, it is not possible to say with any confidence whether endometrial scratching can increase the probability of pregnancy.
It is important to also consider potential adverse events of this procedure (unwanted effects). Unfortunately, only one study reported on pain during the procedure, which was an average of 6 out of 10 on a 10 point pain scale. Doctors recommending this procedure should balance any suggested benefit of endometrial injury against the potential risks. This is especially true if the procedure is performed in the second half of the menstrual cycle, where there is the potential to disturb an early pregnancy. Other factors include any cost or inconvenience to the patient.
What’s next?
More research is needed to confirm whether or not endometrial scratching can truly help couples to get pregnant and have a baby. This research should be in the form of large randomised controlled trials with appropriate methods to avoid bias, and should report on adverse events such as bleeding, pain and infection.
Read more about pregnancy and fertility here
Please visit healthtalk to learn more about the experiences of infertility direct from UK couples: http://www.healthtalk.org/peoples-experiences/pregnancy-children/infertility/going-gp
Sarah Lensen has nothing to disclose.