Clinical trial about the effect of endometrial scratch on pregnancy rates in patients undergoing a treatment with in-vitro fertilization with donor eggs, when doing the endometrial biopsy during the cycle prior to the embryo transfer.

The aim of this clinical trial is to investigate whether an endometrial scratch during the cycle prior to embryo transfer cycle is effective or not in increasing pregnancy rates. Previous studies about this issue have not shown clear conclusions about the effectiveness of this method.

The endometrial scratch is a simple technique that consists in performing a mild injury to all the internal walls of the uterus with a Pipelle Cournier.

To achieve the trial objective, all participating patients are randomly divided into two groups. Once patients decide to participate in the trial, they are assigned to each group according to the randomization list:

Group A: Patients with transfer of fresh embryos after taking an endometrium biopsy during the previous cycle and then following the conventional preparation protocol.

Group B: Patients with transfer of fresh embryos with the conventional preparation protocol.

Inclusion Criteria:

• Female undergoing IVF treatment with donor eggs

Exclusion Criteria:

• Severe male factor ( less tan 2 million spermatozoa per ml )
• Uterine abnormalities

Adverse effects will be controlled for every patient for 12 months, starting on the day of randomization.

All-Cause Mortality and Serious and Non-serious Adverse Events were monitored since all patients were followed up and contacted to assess the results of their pregnancies and determine the possible negative events. In our population no deaths or Serious Adverse Events were observed.

We did not observe any Mortality or Adverse Events related to the intervention, since this intervention does not differ from conventional clinical practice.