Routine prenatal ultrasound screening for fetal abnormalities: 22 years' experience.

We describe the results of routine obstetric ultrasound examination over a period of 22 years (1970-91) at the Institut Universitari Dexeus, Barcelona, Spain. A total of 1006 malformed fetuses or neonates were identified at abortion or delivery. The prevalence of fetal abnormalities was 3.03%. Fetal anomalies were diagnosed antenatally in 788 (78.33%) cases. Early prenatal diagnosis (before 22 weeks of gestation) was made in 598 (59.44%) cases. The detection of malformed fetuses increased from 19.75% in the first phase of the study (1970-74) to 96.33% in the last phase (1990-91). The specificity of the method was over 99% throughout the study period. The most frequently diagnosed anomalies were urinary tract anomalies (22.86% of cases), followed by head and neck anomalies (18.68%), musculoskeletal anomalies (8.64%), heart anomalies (7.35%) and gastrointestinal anomalies (7.35%). The earliest diagnosed malformations were those of the thoracoabdominal wall (81.08%), followed by defects of the urinary tract (70.86%) and of the diaphragm (70.83%).