Assessment of the newborn's condition

Basic principles of examination in perinatology

A comprehensive assessment of the future newborn's condition is inextricably linked with a thorough examination of the pregnant woman herself. According to standardized protocols, the obstetric examination includes general methods, including external obstetric examination. The most critical component is pelvimetry—measuring the pelvic dimensions in strict compliance with established rules.

Secondly, prenatal screening is performed at designated gestational periods. Its purpose is to identify risk groups for congenital abnormalities using biochemical and ultrasound methods. To obtain objective information about intrauterine development, specific methods for assessing fetal status are used strictly depending on the trimester of pregnancy.

Ultrasound diagnostics and echo markers of pathologies

Ultrasound examination of the fetus and placenta is performed for specific purposes. Special attention is paid to the second trimester, when specific echo markers associated with an increased risk of chromosomal abnormalities are visualized. The most significant ultrasound signs include:

• «Banana» sign: pathological alteration in the shape of the fetal cerebellum. Due to a characteristic curvature, the structure resembles a banana.
• «Lemon» sign: characteristic deformation of the skull contour detected on an axial slice. Inpression of the frontal bones gives the fetal head the shape of a lemon.
• Ventriculomegaly: pathological enlargement of the cerebral ventricles. On sonograms, this may be accompanied by signs of severe complications, such as Grade IV intracranial hemorrhage in utero (Grade IV intracranial hemorrhage in utero), recorded at 34 weeks of gestation.
• Hyperechoic bowel: abnormal increase in the echogenicity of the bowel loops. Their brightness on the monitor becomes comparable to bone density.

Additionally, ultrasound allows the detection of cystic hygroma of the neck—an extensive fluid-filled mass adjacent to the cervical region of the fetal head. In severe cases, this pathology is visually confirmed in the phenotype of the abortus after pregnancy termination.

Biochemical screening and risk calculation

Biochemical markers play a key role in assessing the probability of giving birth to a child with Down syndrome. The typical picture in this chromosomal pathology includes a decrease in PAPP-A protein levels below normal and a simultaneous increase in $\beta$-hCG levels above normal for the corresponding gestational age.

It is important to understand that deviations in these markers are not entirely specific. The concentration of PAPP-A and $\beta$-hCG in maternal blood can be influenced by numerous factors:

• body weight of the pregnant woman;
• concomitant diseases (diabetes mellitus, liver diseases, gestosis);
• presence of rhesus incompatibility;
• multiple pregnancy;
• threatened miscarriage, missed abortion, or intrauterine fetal death;
• various placental pathologies, including hypoplasia, hyperplasia, cysts, tumors, or placental abruption sites.

To improve diagnostic accuracy, the data is processed using computer software that calculates individual risk. An indicator of more than 1 in 250 is considered the threshold value.

Invasive and non-invasive prenatal diagnosis

If the individual risk exceeds the 1 in 250 threshold, echo markers of pathologies are identified, or critical changes in PAPP-A and $\beta$-hCG levels are observed, invasive diagnostics is indicated for the patient. These methods allow obtaining fetal-derived tissues for cytogenetic testing. The choice of method depends on the gestational age:

1. Chorionic villus sampling: performed in early stages (8–12 weeks).
2. Amniocentesis: optimal at 16–22 weeks (early option possible at 13–14 weeks).
3. Cordocentesis: performed starting from the 18th week of pregnancy.

Invasive procedures make it possible to diagnose all forms of chromosomal abnormalities, determine fetal sex, and perform molecular diagnostics of hereditary diseases (cystic fibrosis, phenylketonuria, hemophilia, Duchenne muscular dystrophy).

A safe alternative is non-invasive prenatal testing. The essence of the method lies in the analysis of cell-free fetal DNA circulating in the pregnant woman's bloodstream. Risk assessment by this method is possible starting from the 10th week of pregnancy.

Preimplantation genetic diagnosis

In in vitro fertilization (IVF), the genetic status is assessed before embryo transfer. Preimplantation diagnosis aims to detect mutations using micromanipulations. The material consists of oocyte polar bodies or embryonic cells (blastomeres, trophectoderm cells). Biopsy is usually performed at the 8-blastomere stage by extracting material with a micropipette.

A specific indication is determining the Rhesus blood group of the embryo. This is critically important for patients with Rhesus sensitization and severe forms of hemolytic disease in their history, in order to select exclusively a Rhesus-negative embryo for transfer.

Class and exam questions

What else to study on this topic

• Rules and technique of pelvic measurements (pelvimetry).
• Objectives and techniques of external obstetric examination in pregnant women.
• Contraindications and technique for performing invasive diagnostic methods.
• Molecular diagnostics of hereditary diseases (cystic fibrosis, hemophilia, Duchenne muscular dystrophy).

Other topics in the "Obstetrics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.