Ultrasound screening for structural defects in early pregnancy.

Since 1975, the primary method of antenatal diagnosis of structural defects has been by ultrasound visualisation. Improvements in equipment and operator experience have progressively increased the confidence and reliability of this technique which in 1982 provided a 100% detection rate. (Alternative methods are relatively costly and in our opinion, unsatisfactory). Total population screening for structural defects is entirely feasible by ultrasound and acceptable to the patient. Serum alpha feto-protein screening techniques are less reliable- generate unnecessary anxieties, and have given no supplementary assistance to detection rates in our experience. Ultrasound is considered to be the best screening technique available to the obstetrician for the detection of structural defects in early pregnancy and obviates the use of amniocentesis as a confirmatory procedure.