ABSTRACT
Since ultrasound was introduced as an imaging technique in obstetrics, there has been significant improvement in the quality and resolution of images obtained. The early static scans permitted the detection of gross lesions, such as anencephaly. The introduction of real time (B mode) imaging with increased resolution has permitted fetal anatomy to be examined in greater detail and with considerable accuracy such that ultrasound has replaced maternal serum alphafetoprotein measurement as the screening test of choice for neural tube defects in England.
