3D / 4D Ultrasound: State-of-the-Art Technology

In obstetrics, the ultrasound is an essential imaging tool used to clearly visualize the fetus in the womb.

Recent advances in imaging have resulted in the introduction of three-dimensional (3D) and four-dimensional (4D) ultrasound. Used in conjunction with traditional two-dimensional (2D) ultrasound imaging, which has been in use for more than 25 years, 3D/4D ultrasound provides a higher resolution image in actual or “real” time. Such imaging is especially useful for obstetricians who suspect structural abnormalities and need to see specific surface renderings of a fetus. Carol Simmons, MD, an obstetrician/ gynecologist with Greater Pittsburgh Ob/Gyn, is one of the first obstetricians in the area to offer 3D/4D ultrasound to patients and referring physicians. Her group, which practices at Mercy Hospital, has completed more than 1,000 scans since they started using this revolutionary equipment in April 2003.

Dr. Simmons explains that in conventional 2D ultrasound, the body is scanned using a movable probe over the surface of the abdomen. The image received is made up of thin views or “slices” of an image; only one slice may be seen at a time on the screen. While informative, the image does not always give an adequate view of the structure being studied. In 3D ultrasound, the technologist sweeps a probe over the maternal abdomen. A computer takes multiple images and renders a life-like 3D image. With 4D ultrasound, the computer takes the images as multiple pictures while the technician holds the probe still and simultaneously renders a 3D image in real time on a monitor. The difference between the 3D and 4D is that 4D is real-time imagery.

In most cases, the standard 2D ultrasound is taken, and then the 3D/4D scan capability is added if an abnormality is detected or suspected. The 3D/4D is then focused on a specific area, not the whole body, to provide the details needed to assess and diagnose a suspected problem.

Dr. Simmons routinely will do a quick 4D scan of the fetus’ face at the end of a routine exam, providing the parents with a color photo that clearly shows their fetus’ features. Many parents-to-be have commented on the clarity and high quality resolution, even noting genetic similarities to family members. In this respect, Dr. Simmons says the 4D scan also helps to promote maternal and paternal bonding.


According to Dr. Simmons, 4D ultrasound and its clear, real-time images, may be particularly useful in detecting fetal abnormalities and structural problems, such as cleft lips; hand, spinal, and cardiac deformities. The results from these scans can be shared with the referring physician, a pediatric surgeon, or others who will treat the newborn after birth so they may prepare for post-delivery care. The new technology can also be used to determine fetal age, analyze fetal development, evaluate multiple or highrisk pregnancies, and diagnose ectopic pregnancies. 4D ultrasound also has practical applications in gynecological practice: scans can be used to detect endometrial polyps, uterine fibroids, and ovarian tumors.

There are limitations to adequate visualization of fetal anatomy with 3D/4D technology. Dr. Simmons notes that if there is inadequate amniotic fluid surrounding the fetus, or if the fetus has its face in the posterior position in the uterus, there will be difficulty visualizing structures and the face. Despite these minor limitations, Dr. Simmons clearly sees the value of this innovative new imaging equipment and foresees that this latest 3D/4D technology will one day be standard equipment in ob/gyn offices.

“If a woman is at risk for fetal abnormalities or other problems, then the 3D/4D ultrasound is available now to help get a better picture of the fetus,” notes Dr. Simmons. “This is an area that is still evolving; we are just beginning to evaluate where we can best use the technology in the future.”

The 3D/4D technology is paid for by most major insurances when medically indicated.

Editorial provided by Greater Pittsburgh Ob/Gyn &MercyLink.