ABSTRACT
The assessment of fetal growth, gestational age, and detection of fetal malformations are still the main goals of ultrasound examination in obstetrics. In the majority of perinatal centers, the amniocentesis for prenatal diagnosis is performed at 16 weeks of gestation. However, the amniocentesis performed at 15 or 20 weeks of gestation can hardly be considered as an exception. The second-trimester “early” amniocentesis and third-trimester “late” amniocentesis are actually the same procedures. Only the indications are different. For the last amniocentesis, the two most frequent ones are Rh incompatibility and estimation of fetal lung maturity. The most important fact is that traditional noninvasive methods for fetal monitoring, such as cardiotocography and ultrasound, usually fail to differentiate the subgroup of jeopardized fetuses from growth-retarded fetuses in good condition with normal P0z values. Continuous ultrasound monitoring of the biopsy procedure enables safe and precise placement of the instrument.
