When multiple in vitro fertilization cycles fail despite good quality embryos and a good prognosis, patients understandably want answers. Unfortunately, reproductive endocrinologists cannot always provide them.
Instead, physicians begin offering additional treatments with the hope of improving the chances of embryo implantation. One such add-on is endometrial scratching.
History and Methods of Scratching the Endometrium for IVF
In 2003, a group of reproductive endocrinologists noticed that their patients were more likely to become pregnant following an endometrial biopsy What became known as endometrial scratching, or endometrial injury, began to catch on as a method of intentionally disrupting the endometrium with the goal of increasing receptivity, and the reproductive medicine community began researching its effectiveness.
The original technique — performing an endometrial biopsy — is the one most commonly practiced. The biopsy is typically performed on day 21 of the cycle before a patient undergoes IVF. A pipelle catheter is inserted through the cervix and maneuvered around the uterus to "scratch" the endometrium. Although it can be painful, the procedure is low-cost, low-risk and can be performed in the office without anesthesia.
How endometrial scratching may improve the chances of pregnancy is not completely understood. The prevailing theory, according to the Journal of Assisted Reproduction and Genetics, is that the repair process following the scratch may make the endometrium more receptive by modulating the expression of glycodelin A, metalloproteinase 1, integrin alpha 6 and laminin alpha 4. This process may also release proinflammatory cytokines, hormones and other growth factors that are vital to implantation.
The Argument Against Endometrial Scratching
The reproductive medicine community was largely in favor of endometrial scratching until new research was presented at the 34th Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in 2018.
The study, which was later published in the New England Journal of Medicine, used a large randomized trial and found no significant differences in clinical pregnancy, miscarriage or live birth rates between the endometrial scratching group and the control group. Additionally, the researchers discovered that patients experience a median of 3.5 out of 10 on the pain scale during the procedure.
Those in favor of discontinuing endometrial scratching say that earlier studies were too small, were biased in conduct or design and did not provide convincing results. In addition to being painful, the procedure comes with risks such as bleeding and infection and costs patients around $500.
The Argument for Endometrial Scratching
Prior to the ESHRE proceedings, a Cochrane review summarizing studies of endometrial scratching preceding an IVF cycle found the procedure improved chances of clinical pregnancy and live birth. A systematic review and meta-analysis published in Fertility and Sterility in 2018 reported higher live birth rates and clinical pregnancy rates specifically for patients who had experienced repeated embryo implantation failure.
Advocates say this potential benefit supports continuing endometrial scratching, at least in select patients. Specifically, the option may be valuable for patients with two or more failed IVF cycles, if provided along with proper counseling about the risks and current research.
Finally, reproductive endocrinologists can accomplish more than just scratching with an endometrial biopsy. A biopsy can help test for chronic endometritis, endometrial receptivity and abnormal expression of specific proteins without a second procedure.
However, the consensus of the reproductive medicine community seems to be that more research needs to be done on the benefits and risks of endometrial scratching before this technique is universally accepted or rejected as a means to improve IVF implantation.
