# Invasive Prenatal Diagnostics: A Cornerstone of Perinatal Management
## 1 Introduction to Prenatal Diagnostics  
In 1955, [PERSON] et al. [1] and others [2, 3, 4, 5, 6] were the first to determine the sex of the footus by examining the centrifuged cells of amniotic membranes. The samples were investigated for either the presence or absence of typical sex chromatin mass in cell nuclei. The mentioned chromatin accumulation was later discovered to be an inactive chromosome X and named _Barr body_ after the discoverer. In subsequent years, intensive research regarding amniotic fluid composition was carried out, resulting in the first successful cell culture [7, 8]. This method enabled the demonstration of the foetal karyotype for the first time, marking the beginning of a new era in genetic counselling. In the 1950s and early 1960s, the only methods used in obstetric imaging were based on Roentgen radiation. The main aim of _Pelvinetry_ was the full assessment of the pelvis [9]. For this purpose, X-ray images of four planes of the pelvis were projected. This was applied antennally in order to foresee various complications, such as pelvic inadequacy, or intranatally in the case of a failure to progress during a trial of labour. _Placentography_ is an arterial angiography of the placenta. It was crucial in establishing the absence of placenta praevia [10]. However, despite its undeniable usefulness, radiology has raised many concerns regarding the radiation hazard. The primary concern associated with antenatal radiation is the risk of malignancy. In 1956, [PERSON] et al. [11], and later, others [12, 13, 14], traced an excess number of leukaemia and neoplastic conditions of the CNS, kidneys, and adrenal glands. The majority of reported cases were associated with foetal antenatal exposure to radiation. The previously mentioned complications were the primary reason for the withdrawal of radiologic examinations in pregnant women from everyday clinical practice. The main milestone that opened the door to prenatal diagnostics was the introduction of the world's first contact compound scanning machine, the _Diasonograph_, by [PERSON] et al. [15]. This visionary invention consisted of a probe mounted on a patient's bed with piezo-electric transducer crystals responsible for transmitting and receiving echoes. The examination involved the slow movement of the probe across the abdomen in order to scan deep tissues from as many angles as possible. The whole process took approximately2 min, culminating in a cross-sectional picture created on a cathode ray tube. The images presented were crude and lacked grayscale. However, this groundbreaking invention has broadened the horizons for further research [16]. It soon became obvious that an ultrasonographic scan of the foetal head, called _cephalography_, is useful in predicting foetal weight [17] and assessing intrauterine growth [18]. Moreover, in 1969, [PERSON] et al. [19] demonstrated, that a precise measurement of the bipartietal diameter in the 20 th to 30 th week of gestation is a reliable method of determining the delivery date in pregnancies of uncertain maturity. Obstetric ultrasonographic examination soon established this as an inherent element, which has since been in use for many years. In 1975, [PERSON] et al. [20] improved this method by introducing the abdominal circumference measurement at the liver and umbilical vein level as a valuable predictor of foetal weight, as well as in growth-restricted foetuses. At this time, ultrasonography was only reserved for more advanced pregnancies. In 1973, [PERSON] et al. [21] introduced the first detailed biometry charts of foetal crown-rump length from the 7 th to the 16 th week of gestation. At that time, a tremendous development in the field of prenatal diagnostics was observed. It was initiated by [PERSON] et al. [22], who, in 1972, presented a case of prenatally diagnosed anencephaly, followed by elective termination of pregnancy. On this basis, he conducted systematic research regarding neural tube defects.