Endometrial scratching: can it favor embryo implantation?
In an assisted fertilization process, the main difficulties to be faced are obtaining an embryo, possibly at the blastocyst stage , and then implanting the blastocyst in the uterus.
For implantation to take place, the embryo must find the right conditions to adhere to the endometrium, but even in the best obtainable it is not certain that it will be able to nestle. In fact, there are many factors that influence the implantation of the embryo, from the quality of the oocytes, sperm, the embryo itself, but also the transfer and laboratory procedures.
Without forgetting that an implant may not take place due to the presence of undiagnosed fibroids or polyps, for example, or due to endometritis.
Promote implantation with endometrial scratching
While on the one hand efforts are being made to “select” the blastocyst to be transferred to the uterus with ever greater accuracy, as far as implantation is concerned, there have been no major steps forward in recent years. However, there is more and more talk of a technique called endometrial scratching which according to some could increase the possibility of implantation and therefore of having a baby in one’s arms.
There are several causes that induce a couple to resort to assisted fertilization techniques. These causes have different solutions: from the simplest (such as drugs to stimulate ovulation and intrauterine insemination IUI ) to the most complex such as IVF and ICSI.
In vitro fertilization (IVF) requires both the collection of sperm and oocytes for fertilization to take place in the laboratory, to then transfer the embryo, or embryos, into the uterus.
Endometrial scratching is currently being proposed as an adjunctive procedure to increase the likelihood of pregnancy in women undergoing IVF, but the utility of this technique is still debated.
What is endometrial scratching?
The endometrium is a layer of tissue that lines the inner wall of the uterus. The implantation of the blastocyst in the uterus represents one of the first fundamental steps for the onset of pregnancy.
The endometrial scratch is a procedure which consists in injuring the endometrium with a special instrument . It is believed that this injury may somehow increase the chance of implantation of the embryo and therefore of having a pregnancy.
Endometrial scratching can be done with many different tools. The most common technique is the procedure of an endometrial biopsy, normally performed with a micro-catheter called a pipelle, which is 3mm wide. The pipelle is inserted through the cervix (neck of the uterus) into the womb, where it is moved back and forth and rotated in a way that causes some injury. This is the same procedure that a gynecologist would take for an endometrial biopsy. It is a simple, low-cost procedure that can be performed on an outpatient basis without anesthesia in just a few minutes. It may cause some discomfort or pain. It is not a procedure without complications (pain and bleeding) and risks, even if very rare, such as infections or uterine perforation.
Why might it be useful to scratch the endometrium?
It is not clear which biological process can lead to a higher probability of pregnancy. One theory is that scratching the endometrium causes some sort of inflammatory response in the endometrium, similar to what a scratch causes anywhere else on the body. The inflammatory response after scratching is thought to improve the endometrial environment and make implantation of the embryo more likely.
Is endometrial scraping for targeted intercourse or IUI?
There are some Cochrane reviews that have only considered randomized trials of endometrial scratching in women trying to get pregnant with targeted sex or IUI. And others evaluating the usefulness of endometrial scratching before IVF.
The review of the utility of endometrial scratching with targeted intercourse or IUI included nine randomized controlled trials with a total of 1512 women. Most of the couples had unexplained infertility (meaning that after doing all the routine tests no valid explanation could be found as to why the couple could not get pregnant).
All of the findings from these randomized trials suggest that there is a benefit from endometrial scratching. However, the studies have significant limitations and therefore the results may be unreliable. Therefore, it is not possible to state with certainty that endometrial scratches can increase the probability of pregnancy in couples who have targeted intercourse or who undergo intrauterine insemination.
Is endometrial scraping for targeted intercourse or IUI?
A Cochrane review included 14 clinical trials (2128 women) to evaluate the effects of endometrial scratching on IVF outcomes. Thirteen of these studies investigated the endometrial lesions made during the menstrual cycle preceding the embryo transfer (7 days before the transfer cycle). Only one study investigated the endometrial damage on the day of oocyte retrieval, which occurs only a few days before of the day the embryo is transferred to the uterus.
The studies reviewed suggest that endometrial scratching performed during the month preceding the start of ovarian stimulation moderately improves a woman’s chances of becoming pregnant and carrying a baby.
Furthermore, it has been seen that the endometrial lesion performed on the day of the oocyte retrieval (pick-up) reduces the chances of pregnancy.
There is no certain result on the benefits of endometrial scratching. The quality of the evidence is reduced because either the number of participants in the studies is insufficient or because a large percentage of the studies included in the review have important limitations in the methods used.
Although current evidence suggests some benefits of endometrial scratching, more data is needed to confirm whether endometrial scratching can indeed help couples get pregnant and carry a baby.
This is why it is not a procedure that is routinely recommended as it is still considered experimental and not supported by sufficient evidence.
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.