As an internist, I occasionally encounter patients who have difficulty conceiving and I refer them to a reproductive medicine specialist for evaluation. The prevalence of infertility is about 15% among reproductive-aged couples in the United States. Causes of infertility include ovulatory dysfunction, ovarian failure or diminished ovarian reserve, tubal disorders, uterine disorders, and male factors that affect sperm production.
In vitro fertilization (IVF) is an assisted reproductive technology designed to overcome infertility and achieve conception. The general steps of IVF are ovarian stimulation, egg extraction, fertilization in the laboratory, embryo culture, and implantation of embryo into the uterus through the cervix.
In the forty years since the birth of Louise Brown — the first “test tube baby” — IVF has resulted in millions of successful pregnancies. In 2016, more than 70,000 babies were conceived using IVF in the United States, accounting for about 1.7% of pregnancies. A number of adjuvant techniques and modifications during the IVF process have been proposed to help achieve conception. Endometrial scratching is one technique that involves the purposeful disruption of the endometrium with the goal of enhancing the chance of conception after embryo transfer. Although it is commonly used, data to support its use is limited.
In a large, pragmatic, randomized trial published in NEJM, Lensen et al. found that endometrial scratching did not increase the rate of live birth, compared with no intervention among women undergoing IVF. In an accompanying editorial, Mol and Barnhart at Monash University and University of Pennsylvania note the limitations of prior trials that suggested a benefit from this technique and argue that endometrial scratching should not be used and “offer false hope.”
The following NEJM Journal Watch summary explains the study.
Endometrial Scratching Before In Vitro Fertilization Is Not Warranted
Robert W. Rebar, MD reviewing Lensen S et al. N Engl J Med 2019 Jan 24 Mol BW and Barnhart KT. N Engl J Med 2019 Jan 24
Several small trials have suggested that using a plastic biopsy catheter to scratch the endometrium prior to in vitro fertilization (IVF) might increase the likelihood of implantation and raise live birth rates; accordingly, many clinicians have adopted this procedure despite unproven efficacy and higher cost. These considerations led investigators to enroll >1300 women undergoing IVF in an open-label trial at centers in five countries to assess the procedure's efficacy. Participants were randomly assigned to endometrial scratching (between day 3 of the cycle preceding and day 3 of the embryo-transfer cycle) or no intervention.
Live births occurred in 180 of 690 women (26%) in the endometrial-scratch group and 176 of 674 women (26%) in the control group. There were no significant between-group differences in rates of ongoing pregnancy, clinical pregnancy, multiple pregnancy, ectopic pregnancy, or miscarriage.
Comment: IVF has spawned many adjunctive procedures in attempts to increase live birth rates; endometrial scratching has always struck me as one of the more improbable. This trial should lay to rest the belief that this procedure has any efficacy — in any case, I believe it is offered less often in the U.S. than in many other countries.
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James Yeh, MD MPH is an internist and assistant in medicine at the Massachusetts General Hospital and an instructor in medicine at Harvard Medical School. His clinical and academic interests are in evidence-based medicine, medical education, continuing medical education, cardiopulmonary diseases, cardiovascular risk reduction, critical illness, care transition, polypharmacy, and health communication. He was a NEJM editorial fellow in 2015-2016.