[Ultrasound in pregnancy--practical aspects].

According to the payments agreement of the health insurance law two screening-scans at 10-13 weeks and 20-23 weeks respectively are part of the low-risk pregnancy care. The first-trimestre-scan includes the determination of the gestational age, the anatomical integrity of the fetus and the chorionicity in case of monochorionic twins. The 20-23 week scan has to evaluate the fetal growth, fetal abnormalities and the placental site. Doppler sonography is reserved for high risk pregnancies, especially for hypertensive disorders and fetal growth retardation, for the evaluation of fetal anemia in case of blood group alloimmunisation and for the detection of the twin-twin-transfusion syndrome in monochorionic twins.