The use of ultrasound in evaluating problems and complications of genetic amniocentesis

A prospective study of 460 midtrimester amniocenteses performed with ultrasonic guidance was made to determine the problems that occur during amniocentesis and the causes of dry or bloody taps. In 27 instances the needle was seen piercing the fetus. Thickening of the uterine wall, tenting of the membranes, and blocking of flow by the fetus were also observed. The dangers of advancing the needle blindly when no fluid is obtained at the predetermined depth is stressed. The use of active real-time ultrasonic guidance during amniocentesis is advocated.