An ultrasonic diagnostic imaging system produces an extended field of view (EFOV) image. A 3D imaging probe is moved along the skin of a patient above the anatomy which is to be included in the EFOV image. As the probe is moved, images are acquired from a plurality of differently oriented image planes such as a sagittal plane and a transverse plane. As the probe is moved the image data of successive planes of one of the orientations is compared to estimate the motion of the probe. These motion estimates are used to position a succession of images acquired in one of the orientations accurately with respect to each other in an EFOV display format. The motion estimates are also used to display a graphic on the display screen which indicates the progress of the scan to the user as the probe is being moved. The progress may be indicated in terms of probe velocity, distance traveled, or the path traversed by the moving probe.