[Sonographic demonstration of the fetal extremities in the mid-trimester (author's transl)].

In 251 pregnancies fetal extremities were systematically examined by means of an ultrasound sector scanner between the 12th and 28th week of gestation. The procedure is demonstrated by typical pictures. The long tubular bones, hands and feet were visualized regularly, and differentiation of radius and ulna or tibia and fibular was possible. Studies took between 5 and 25 minutes. In all cases the length of the diaphyses was determined, resulting normal growth tables and rate of growth curves. Between the 12th and 28th week, the humerus grows from 9 to 51 mm., the radius from 7 to 46 mm., the femur from 10 to 55 mm., and the tibia from 8 to 48 mm. Sonographic depiction of fingers and clavicles was also quite successful. For best results, examinations were done between the 16th and 20th week. In three fetuses later aborted, sonographic and direct (after preparation) measurements of bone length for the diaphysis differed by no more than 4%. The study shows that visualization of the extremities regularly succeeds in the mid-trimester. A multitude of localized or systemic limb malformations may be recognized. In cases with known predisposition to malformations a regular ultrasonic checkup should be performed, thus extending the scope of prenatal diagnosis.