SPECIFICITY OF ANTENATAL ULTRASOUND IN THE YORKSHIRE REGION - A PROSPECTIVE-STUDY OF 2261 ULTRASOUND DETECTED ANOMALIES

Objective To evaluate the specificity of the ultrasound diagnosis of f etal anomalies. Pregnancies which proceeded to termination and ultraso und-diagnosed fetal anomalies which were not offered termination were considered. Design Prospective, region-wide study over three and a hal f years. Setting Cases were identified through 25 ultrasound departmen ts representing the 15 districts in the Yorkshire Region. Subjects Pre gnant women with an ultrasound-diagnosed fetal anomaly. Main outcome m easures Information obtained from the ultrasound report was compared w ith the outcomes determined by cytogenetics, postmortem or paediatric examination. Results Of 2261 pregnancies with an ultrasound-diagnosed fetal anomaly 369, (16%) were terminated and 357 (97%) were followed b y postmortem examination. Ultrasound findings exactly matched those of the postmortem or were accompanied by additional anomalies in 325 cas es (91%). In 32 cases ultrasound findings were not confirmed by postmo rtem, but in 30 of these the decision to offer termination remained ju stified because the correct diagnosis was judged equally or more serio us. Two (0.5%) were terminated for an anomaly which subsequently prove d less severe than predicted on ultrasound. Ultrasound significantly o ver- or under-diagnosed a major fetal anomaly in 27 of the 1139 (2.4%) cases in which an anomaly was detected, but the pregnancy was not ter minated. Conclusion Termination of pregnancy was based on the correct prognosis in over 99.5% of cases. This does not obviate the need for p athological examination of the fetus which changed or refined the diag nosis in 35% of cases.