Objective evaluation of ultrasound guided embryo transfer: analysis of 198 video recordings

Abstract

OBJECTIVE: Although most IVF programs perform embryo transfers with ultrasound guidance, there is still some controversy in the literature regarding this issue. While most investigators conclude that ultrasound (US) guidance results in improved pregnancy rates (PR), others find no benefit or believe that US may be useful for less experienced physicians. This study was designed to assess systematically the clinical value of transabdominal US guidance of embryo transfer and its impact on the outcome of IVF. DESIGN: Prospective, systematic review of 198 video recordings of US guided embryo transfers and analysis of the aspects of the transfer procedure and technique potentially involved in the success of embryo transfer. MATERIALS AND METHODS: 198 patients who underwent transfer of fresh or frozen embryos using autologous or donor oocytes, from June 2007 to April 2008. All transfers were performed by the same physician using a soft wallace catheter; when canalization of the cervix was difficult a wallace malleable stylet was used. Four embryologists and 6 ultrasonographers participated. The following variables were analyzed: embryologist, ultrasonographer, quality of US visualization, presence of blood or mucus on or in the catheter, placement of the catheter tip, movement of the embryo fluid, intensity of injection (slow, intermediate, strong), distance of the bubble from the fundus at the end of the procedure. Additional parameters were patient age, embryo quality, endometrial thickness, length of the uterine cavity. Outcome measures were the implantation rate (IR) and PR. RESULTS: Implantation and pregnancy rates were higher for embryo transfers in which the ultrasound visualization of the endometrium and the catheter was best, as opposed to transfers in which visualization was suboptimal or poor. Poor visualization was associated with the presence of mucus or blood on the transfer catheter. Greater experience of the ultrasonographer was associated with better visualization. Use of the rigid malleable stylet did not affect IR and PR. Intensity of injection influenced implantation and pregnancy rates: intermediate strength was better than slow or strong. CONCLUSIONS: Optimal ultrasound visualization of the transfer procedure reduces the occurrence of traumatic events and allows placement of the catheter tip in the desired location, resulting in higher implantation and pregnancy rates. In order to be beneficial, US guidance must be performed by experienced ultrasonographers specifically trained in this procedure.