It is likely that four-dimensional ultrasound is more of an incremental development, rather than a revolutionary change, in ultrasound imaging technology. This technology is currently an add-on to two-dimensional ultrasound, rather than a replacement for it. As with many medical technologies, much depends on the skill of the operator, and there is a long learning curve. At present there is little in the published literature to indicate how much of an improvement in diagnostic accuracy it offers or what its impact would be on patient management. There is potential for four-dimensional ultrasound to be used inappropriately: by pro-life groups to discourage women from having abortions, or by private clinics to 'enhance parental bonding'. The medical director of a perinatal ultrasound clinic in one US hospital explains that "good medical sonographers can determine 'very little' additional information about the health of the fetus from a 3-D or 4-D ultrasound compared with the traditional two-dimensional image."