Ultrasonic diagnosis using high-resolution devices is a routine procedure in early pregnancy. Malformations can be diagnosed at very early stages, cardiac activity can be measured and the position of the placenta can be determined. Doppler sonography allows observation of the embryonic or fetal blood flow.
Fetoscopy (embryoscopy) consists of the transabdominal insertion of an endoscope into the amniotic sac guided by ultrasound. It allows for diagnosis of skin afflictions and malformations of the fetal surface that cannot be identified through sonography. In addition, punctures of an umbilical vessel under ultrasound can be performed for diagnostic purposes.
Maternal blood is used to measure alpha-fetoprotein in particular. Increased levels may indicate defects of the neural tube (NTD) and the ventral abdominal wall. Decreased values can signify aneuploidy (for example, trisomy 21). Fetal cells can also be isolated for cytogenetic diagnosis. In addition, PCR and FISH can be used to diagnose trisomies.