If you've tried and failed to get pregnant, many couples turn to a fertility clinic or gynaecologist. IVF is usually recommended and carried out. For many, this treatment alone is enough to fulfil their desire to have a child. However, some women continue to suffer from implantation failure. Often the reason for this can be found and treated with further tests, but in some cases no reason can be found. In these cases, endometrial scraping is sometimes recommended. However, this method is controversial. Today's blog aims to shed some light on this topic.

What is implant failure?

In the context of pregnancy, implantation is when the fertilised egg attaches to the lining of the uterus. In medicine, the term nidation is also used. This refers specifically to what happens in the womb, as other things can be implanted in medicine.

Implantation takes place about a week after fertilisation. At this point, the embryo already consists of about 125 individual cells. Complex communication mechanisms allow the fertilised egg to attach to the lining of the uterus. The conditions for this attachment vary throughout the menstrual cycle. It is therefore normal for implantation to sometimes fail simply because of timing.

The situation is different for patients who have chosen IVF. Here, hormone therapy is usually given before the eggs are collected. This ensures that the eggs are at their most mature at the time of retrieval. It also means that the doctors know exactly where you are in your cycle on each day. This means that the exact time for implantation of the embryo can be chosen.

Even with IVF, the success rate is never 100%. If several IVF attempts fail, this is called implantation failure. More tests are usually done to find out why. Changes in the lining of the uterus, such as endometriosis, or hormonal imbalances are often to blame. In these cases, appropriate treatment can help. For other women, however, there seems to be no real cause. In these women, it may be possible to try to stimulate the lining of the uterus before insemination. This is where endometrial scratching comes into play.

How does endometrial scratching work?

Scratching is exactly what the name suggests. The endometrium, the lining of the womb, is scratched with a pipette. It sounds more brutal than it is. It is similar to taking a sample of tissue for a biopsy. The pipelle can be inserted without anaesthetic. The whole of the uterine wall will then be slightly scarred. The procedure itself is not usually painful. The incision may cause some bleeding and, in very rare cases, the uterus may become inflamed.

It is not clear exactly how these minor injuries stimulate the uterus to nidate. For the wounds to heal, new cells need to be made to replace the broken cells after the wound has closed. So the body has to stimulate cell growth and division in the endometrium. It does this by secreting growth factors and other messengers called cytokines. It is thought that the presence of these substances during IVF treatment helps the lining of the uterus to accept the embryo.

For the treatment to be effective, it must be planned in advance. Scratching should be done one cycle before the planned IVF, so that the wounds have healed by the time of implantation, but growth processes are still ongoing.

Although there is no scientific consensus on the use of scratching, it is still offered in many fertility clinics and is often performed. Research is also being carried out into the benefits and risks, so hopefully some of the unanswered questions will soon be answered.

What are the arguments in favour?

Several studies have been published on this topic in the past. A study from 2011 is linked more frequently on the websites of the clinics. In this study, 591 women from 5 different series were examined. In four of the series, scratching was done in the month before fertilisation, and in one series it was done in the same cycle. Women from the first four series had a significantly higher pregnancy rate. But beware, while this study is a reputable source, it only compares different scratching times. The study does not compare women who did not receive this treatment (see https://pubmed.ncbi.nlm.nih.gov/22786529/).

However, there is also no evidence that the treatment reduces the chances of pregnancy. The risk of side effects is also very low. This means that, in the worst case, the women have the same chances through this intervention as they had before.

What speaks against it?

Despite the low risk, scratching remains an invasive procedure. In principle, there is always a residual risk of inflammation or similar complications with any intervention, no matter how small.

A large-scale study on this issue was published in a renowned English journal in 2019. In this study, 1364 women were randomly divided into two groups. One group received artificial insemination without incision of the endometrium, the other with incision of the endometrium. In both groups, 26.1 % of the women had a successful pregnancy with a live birth. Thus, neither a negative nor a positive effect of curettage could be proven (cf. https://www.nejm.org/doi/10.1056/NEJMoa1808737).

Because of the unclear effect of the treatment, the costs are not covered by the health insurance funds. So in addition to the costs for artificial insemination, you also have to pay for an intervention whose effectiveness has not really been proven.

If you have already had several unsuccessful IVF attempts, you may be desperate because you want a pregnancy so much. This is perfectly understandable, but you should still ask your physician about each procedure. You can also compare the websites of different clinics. Some advertise the treatment, others do not. If sources are given, you can read them. This way you can gather reliable information and make a decision for yourself. Scratching is certainly not a particularly dangerous procedure that is strongly discouraged, but it is an extra burden that you are unlikely to benefit from.