Ultrasound guidance has been suggested as an aid to optimize embryo transfer (ET), as it may facilitate an atraumatic insertion of the catheter and ensure correct location in the uterine cavity before depositing the embryo(s). A number of commercially-available catheters are echogenic which improves visualization allowing for real-time feedback about the location of the catheter during ET. Although most ETs are performed easily and quickly with either the clinical touch or with ultrasound-guided techniques, proponents of ultrasound guidance list several possible advantages. Transvaginal ultrasound provides better visualization of the cervical canal and uterine cavity than transabdominal scanning, and some have studied this approach for ET. One promising technology to improve ET technique may be the real-time 3D ultrasound, i.e., 4D ultrasonography. There are currently a few studies in the literature suggesting improved visualization of catheter location and embryo disposal by using 3D and/or 4D ultrasonography technique.