Long-term experience of general ultrasound screening in pregnancy.

Since January 1, 1974, 43,000 routine ultrasound examinations have been performed on 22,400 pregnant women in the Department of Obstetrics and Gynecology, Malmö General Hospital. At the present time, one examination is performed in the seventeenth week of pregnancy and one in thirty-third week. At the first examination, the number of fetuses, fetal anatomy, cardiac activity, and placental site are indicated. Fetometry is performed. Gestational age is adjusted according to the value of the biparietal diameter. The second ultrasound examination is aimed at detecting fetal growth deviations and malformations. In 15% of all pregnancies, ultrasound corrected gestational age by more than 14 days. Ultrasound appeared to be superior to the clinical assessment in 88% of these discrepant pregnancies in predicting date of delivery. The early examination detected 98% of the twin pregnancies, with no false positive results. If an ultrasound examination had been performed within 3 weeks of delivery, 92% of the fetuses with growth retardation were detected. Altogether, the program detected 60% of the growth-retarded fetuses. In 0.4% of the examinations, malformations were detected (0.6% during the last 2 years). A cost-benefit analysis suggested that large economical gains are to be realized by screening. However, organizational and educational problems must be properly solved before general screening is offered to a healthy pregnant population.