Embryo transfer techniques have emerged as 1 of the most important variables during in vitro fertilization. Two-dimensional ultrasound guidance is an integral part of this procedure and a method to monitor catheter passage through the cervix into the endometrial cavity. Catheter placement may better be achieved with 3-dimensional monitoring to assess the relationship of the catheter tip to the uterine cavity. The purpose of this study was to compare the precision of catheter placement and position by 2- and 3-dimensional ultrasound.

Twenty-four patients were studied. The cervix, uterus, and endometrial cavity were prescreened in 2 dimensions at the midline in the longitudinal plane of the uterus. Embryo transfers were then performed under 2-dimensional guidance. After satisfactory catheter placement and transfer of the embryos, the catheter was held in place for 60 to 120 seconds. During this interval, an automated, single sweep of the uterus and endometrial cavity was performed for net volume acquisition. All images were stored and retrospectively reviewed. Embryo transfer catheter placement with 2-dimensional ultrasound guidance was then compared with the images obtained in 3 simultaneous planes.

Visualization of the embryo catheter tip with 2-dimensional ultrasound was achieved in all patients. These images suggested that the catheter was 2 cm from the uterine fundus and in the midline. Satisfactory 3-dimensional images for review and comparison were obtained in 21 of 24 patients. Three-dimensional ultrasound images confirmed placement and agreed with findings of 2-dimensional ultrasound images in 17 of 21 patients. In 4 patients, the catheter tip on 3-dimensional ultrasound was observed to be displaced either anteriorly or laterally from the ideal region as suggested by 2-dimensional ultrasound. In 1 case, the catheter tip on 3-dimensional ultrasound was observed to be far laterally in the region of the uterine cornua.

Two-dimensional ultrasound-guided embryo transfer continues to be the standard for image-guided transfers. Data of the present study suggest that the precision of catheter tip placement and consequently embryo transfer may be improved with 3-dimensional imaging. Four of 21 patients studied had catheter tip placement in a different and less-than-ideal area when studied with 3-dimensional ultrasound. Three-dimensional imaging may provide an improvement in embryo transfer technique and have a positive impact on overall pregnancy rates.