All methods of prenatal diagnostics can be divided into biological and physical. The physical methods are X-ray examination of the embryo, ultrasonic examination and fetoscopia. X-ray examination gives the diagnosis of hereditary defect only in the last third of pregnancy. The anencephalia, spinal cord hernia and hydrocephalus are well visible in X-rays.
The variant of X-ray examination is fetographia. The contrast substance is injected into the amnion cavity. This method allows diagnosing alimentary canal atresia, urinary system defects. The fetoscopy provides a visible, real image of the embryo, but it has many side effects and is used very rarely. Many defects of the nervous system are determined with the help of ultrasonic examination. Also, it helps to evaluate defects of the kidney such as polycystosis.