Despite these revolutionary changes in the laboratory, little has changed with the process of embryo transfer (ET). A study to prospectively evaluate the role of cervical mucus removal prior to embryo transfer on pregnancy rates in ART will be undertaken.

ET involves placing the embryo(s) obtained before assisted reproduction technology (ART) into the uterus via a catheter advanced through the cervical canal. Yet this is the final, and in some respects the most critical, process in the sequential events that encompass an ART cycle. If an embryo cannot be delivered to the uterine cavity atraumatically and in a location for optimal implantation, the steps of ovarian hyperstimulation, oocyte retrieval, embryo culture, and embryo selection will have no benefit. Contamination of the catheter with blood may be a marker for difficult ET and has also been linked to poor ET outcomes. When retrospectively assessing outcomes, Goudas et al. (1) demonstrated a clinical pregnancy rate of 50% with no blood, and this rate fell by half when a small amount of blood was noted on the catheter tip. Pregnancy rates fell even further, to 10%, when there was a significant amount of blood (1). Similarly, in a preliminary study, blood or mucus on the tip was associated with a significantly lower pregnancy outcome (2). Blood and mucus were associated with an increased risk for unsuccessful transfers with odds ratios of 1.9 and 1.8, respectively. Although all these data suggest a possible role of cervical mucus in embryo transfer, there is no clinical evidence on the effect of removal of cervical mucus on the outcome of IVF/ICSI. In view of this uncertainty, a study to prospectively evaluate the role of cervical mucus removal prior to embryo transfer on pregnancy rates in ART will be undertaken. It is hypothesized that removal of cervical mucus will achieve higher clinical pregnancy rates.

Inclusion Criteria:

• IVF or OD patients with supernumerary embryos (oocyte's age will be considered as patient's age).
• Normal transvaginal ultrasound at screening, without evidence of clinically significant abnormality consistent with finding adequate for ART with respect to uterus and adnexa
• Single embryo transfer
• Embryo transfer at the blastocyst stage
• Embryo with a morphological classification of ≥3BB

Exclusion Criteria:

• Preimplantation genetic diagnosis and/or screening

All included patients will be blinded of the procedure.