Pelvic 3D ultrasound is a relatively new imaging technology that allows for clear visualization of the pelvic organs and, in the case of pregnancy, the fetus -- including his or her facial features. This test, which is just as safe as traditional, 2D ultrasounds, is often performed at the request of parents rather than for clinical diagnosis purposes. The 3D images create what looks like a still photograph of the fetus, while 4D ultrasound images can create images of the fetus “in motion,” more like a video recording. The optimal time for 3D ultrasound is between 24 and 34 weeks of gestation, with the clearest facial images obtainable during the third trimester. When used for diagnostic reasons, 3D ultrasound can add to the information that doctors receive from a 2D ultrasound – particularly with regard to providing additional views of the uterus that aren’t possible with the traditional imaging. Beyond its use in pregnancy, a pelvic 3D ultrasound may also be used to diagnose and assess the locations of endometrial polyps, submucous fibroids and an intrauterine contraceptive device. It can also be used to assess inborn uterine abnormalities and to help determine a reason for repeated miscarriages.