# Invasive Prenatal Diagnostics: A Cornerstone of Perinatal Management
## 2 Techniques of Invasive Diagnostics
### Amniocentesis
#### 2.1.3 TORCH Infections  
Cytomegalovirusovirus (CMV), _Toxoplasma gondii (T. gondii)_, rubella virus (RBV), herpes simplex virus (HSV), varicella virus (VZV), and parvovirus B19 are classically referred to as _TORCH_ infections [115]. Congenital _TORCH_ infections are a well-described cause of stillbirths, foetal growth restriction, foetal abnormalities, neurodevelopmental impairment, and neonatal death [116]. Precise guidelines in the case of maternal infection are crucial in detecting or preventing a placental transmission. _Toxoplasmosis_--International well-established antenatal screening of pregnant women allows for minimising the frequency of congenital toxoplasmosis. However, because of poor hygienic standards in some developing countries, the incidence rate persists at 1.5 per 1000 live births [116]. An endorsed screening protocol consists of T. gondii IgM and IgG, followed by IgG avidity, enabling more accurate timing of infection. In the case of a confirmed maternal infection, the foetus should be examined for transplacental transmission. In this case, amniocentiss after 18 weeks of gestation should be offered to the patient, followed by a PCR for T. gondii in the amniotic fluid [117]. The risk of transmission increases with gestation at the time of infection and varies from less than 15% at 13 weeks to more than 70% at 36 weeks [118]. In order to minimise the risk of transmission, the patient should start prophylaxis with spiramycin, which is a parasitostatic drug [119]. If a foetal infection is confirmed, the treatment is changed to pyrimethamine, sulfadiazine, and folinic acid (P + S + FA) [119; 120]. However, this therapy can be associated with adverse effects. The most principal adverse effect is haematological toxicity and neutropenia, which are reported to occur in more than half of the treated neonates [121]. Therefore, a risk and benefit analysis should always be carried out before starting therapy, and postnatal management should not be neglected. _Cytomegalovirusovirus_--CMV is currently the most common factor in viral congenital infections, with a global prevalence of approximately 0.2-2% [122]. It is a major cause of central nervous system abnormalities in foetuses and sensorineural hearing impairment among neonates. Despite intensive awareness campaigns in recent years, there is still an unsettling deficiency of knowledge among healthcare providers. Because most adults exposed to CMV are asymptomatic, it is crucial to underline the importance of screening during pregnancy. Each patient should conduct an assay for anti-CMV antibodies in the first trimester. CMV-specific IgM antibodies are observed in serum up to 6-9 months after an acute phase of infection [123]. Therefore, the anti-CMV IgG avidity test is the most reliable source of information about the timing of exposure [124]. Avidity indicates the affinity of antibodies to bind the antigen, hence reflecting the maturation of the immunological response. Anti-CMV IgG with low avidity detected in mothers before 18-20 weeks of gestation identified foetal transmission with 100% sensitivity [125]. According to [PERSON] [126], ultrasound findings might be observed in no more than 5% of infected footuses. Currently, amniocentesis and CMV-DNA PCR are integral parts of diagnosing a foetus with infection. The optimal timing of the procedure is 21-22 weeks of gestation [127]. This is because the virus requires 6-9 weeks to replicate and be excreted through urine [128]. This technique has 90-98% sensitivity and 92-98% specificity [128; 129; 130]. Historically, the topic of screening for CMV in pregnancy was controversial because of the lack of effective treatment. However, at the beginning of 2020, evidence began to emerge regarding the effectiveness of valacyclovir. In 2023, [PERSON] et al. [131] and [PERSON] et al. [132] showed a 65% reduction in the transmission rate in the first trimester and periconceptional period and a 70% decrease in infected neonates. Nevertheless, further clinical trials are needed.