Routine second trimester ultrasound screening for prenatal detection of fetal malformations in Sassari University Hospital, Italy: 23 years of experience in 42,256 pregnancies.

Objective: To establish, for a determined period of time, the effectiveness of a program of ultrasound screening in detecting fetal malformations in prenatal time. To assess the sensitivity, the specificity, the positive and the negative predictive value of the ultrasound screening. To examine the trend of such indexes of diagnostic accuracy in a long time period.

Study Design: The patients admitted to the study had effected at least one ultrasound examination within the second trimester of pregnancy (< or =23 gestational weeks). The examined pregnant women were 42,256 and the period of reference ranged from January 1981 to December 2004. All patients delivered in Gynecologic and Obstetric Clinic of Sassari University, Sassari, Italy.

Results: In the considered period were reported 1050/42,256 (2.48%) cases of fetal malformations, of which 974 single and 76 multiple malformations. The cases of malformations diagnosed in prenatal period were 578/1050 (55.05%), of which 65/578 (11.24%) multiple anomalies. The overall sensitivity was 55.05% (95% confidence interval: 52-58%), with a variability from the 32.95% (cardiovascular system) to 81.05% (central nervous system) in relationship to the typology of the examined apparatus. The overall specificity was 99.88% (95% confidence interval: 98-99.9%), the predictive positive value 91.89% (95% confidence interval: 89-93%) and the negative predictive value 98.87% (95% confidence interval: 95-99%).

Conclusion: The sensitivity of the ultrasound screening undoubtedly appeared to be satisfactory. We believe that, for the examination of some apparatuses, as for the cardiovascular apparatus, with the extension of the standard examination (four-chamber view) to further plans of scanning, sensitivity could subsequently be improved.