Quality of routine ultrasound in twin pregnancy in a Swiss canton

Aims: Optimal prenatal management of twin pregnancies requires diligent sonographical evaluation. In Switzerland the efficiency of routine ultrasound during pregnancy has recently become a point of debate. Aim of this study was to evaluate the quality of routine ultrasound of twin pregnancies in Kanton Aargau. Method: Standardised prospective postal interview of each practitioner caring for twin pregnancies during the time period of August 1st, 1998 to July 30th, 1999 in Kanton of Aargau. We chose the Aargau Kanton as being representative of the Swiss population in general on the basis of its average demographic and geographical condition. In addition, evaluating an entire Kanton allows the comparison of data with the official data of the Federal Statistical Office. Results: 81 twin pregnancy cases were delivered during this time period. 65 interviews could be analysed which provided full information. The first sonographic diagnosis of twin pregnancy was confirmed at a mean of 11 (5 - 32) weeks gestation. All twin pregnancies were diagnosed before the onset of labour. 2/65 of the twin pregnancies remained undiagnosed until the 3rd trimester. In one of these cases the patient had refused an ultrasound examination. In 57/65 cases clear information about amnionicity, but in only 53/65 cases additional information about chorionicity was gained. Conclusion: All twin pregnancies were detected sonographically before delivery. Determinations of amnionicity and chorionicity were possible in 87% and 81%, respectively, which could be improved.