Ultrasound role in embryo transfers

The goal of embryo transfer (ET) is to achieve a successful pregnancy after in vitro fertilization (IVF) treatment. A quick, atraumatic, and anatomically properly placed embryo transfer (ET) has always been regarded as quintessential for the achievement of high IVF pregnancy rates (PR). Several factors that may affect the success of an ET have been studied: Ease of the transfer, the location of the embryo deposition, the pre-ET trial transfer, the type of catheter used, the value of resting after ET, and the experience of the physician performing the transfer. The use of ultrasound guidance for ET has been shown in prospective randomized studies as well as meta-analysis to significantly increase embryo implantation, clinical pregnancy and live birth rate, and the easy transfer rates over clinical touch ET. Ultrasound guidance had no effect on multiple and ectopic pregnancy rates as well as on miscarriage rates. The optimal area of embryo deposition in the uterine cavity is probably 1.0-1.5 cm from the fundus resulting in higher PR. US guidance allows accurate visualization of the mid-fundal desirable area. The use of either transabdominal or transvaginal US imaging results in similar PRs. US observation of the marker bubbles has an obvious psychological value to the patient and her spouse. US visualization of post-ET bubble markers reaffirms optimal embryo deposition, but the embryos do move within the uterine cavity after transfer. In addition to the obvious advantages of live US during ET, this technique enables physicians to teach ET without a decline in PR. The disadvantages of US guidance ET are the need for an assistant and the inconvenience for patients of the full bladder. This chapter will review the data available today on the important role of US in ET.