Value of routine ultrasound scanning at 19 weeks: a four year study of 8849 deliveries.

OBJECTIVE: To evaluate the effectiveness of routine ultrasound scanning at 19 weeks' gestation in an unselected population in terms of accuracy of detection of fetal structural abnormality and the effect on obstetric and neonatal care. DESIGN: Prospective study over four years. Scans performed by radiographers with overall supervision by a radiologist. SETTING: Ultrasound department of district general hospital. SUBJECTS: All pregnant women were offered scans; 8523 of 8849 (96%) accepted. MAIN OUTCOME MEASURES: Information obtained from hospital records, genetic analysis, and post-mortem findings. RESULTS: 166 fetal anomalies occurred; 140 were detected at 19 weeks (sensitivity 85%; specificity 99.9%). In 27 cases fetuses were shown to have severely crippling or lethal abnormalities; termination of pregnancy was requested in 25. Early diagnosis influenced timing and place of delivery in babies with severe cardiac or gastrointestinal anomalies. CONCLUSION: Scanning at 19 weeks with availability of termination can reduce perinatal morbidity and mortality. Scanning can be performed in a general ultrasound department with adequate counselling facilities and close cooperation between radiographers, midwives, obstetricians, paediatricians, and the radiologist.