Perinatal screening is done during pregnancy and is a modern and safe way to make sure your baby is okay. The study consists of two parts: ultrasound and biochemical, but there are many reasons why the results may be inaccurate.
Ultrasound Screening
Ultrasound is performed at least three times during pregnancy: at ten to thirteen weeks of pregnancy (first screening), the second time at sixteen to eighteen weeks, and the third at thirty to thirty three weeks. It helps to identify possible fetal defects, the condition and amount of amniotic fluid and many other factors. The main parameters that are guided by when making a diagnosis: CTE (coccygeal-parietal size) and TVP (collar space thickness). For the greatest information content, the CTE should exceed 45, 85 mm; with a smaller fetus, the data may not be accurate. Raises concerns about TVP more than 3 mm, this may indicate various developmental disorders.
Ultrasound results may be distorted due to an incorrectly set gestational age. Usually the doctor focuses on them to clarify the timing, but sometimes the results are adjusted to the obstetric data. This analysis also largely depends on the quality of the equipment and the qualifications of the doctor, therefore, if there are doubts about the diagnosis, it is better to screen again in another clinic before making important decisions.
Biochemical screening
Biochemical screening is a study of blood composition, which is carried out on the same day as an ultrasound scan, or after 1-3 days. It is necessary to donate blood for hCG and PAPP. The hCG hormone promotes the production of cells of the membranes of the embryo, it appears in the blood as early as 6-10 days after fertilization. An increase in beta-hCG in the blood may indicate multiple pregnancies, fetal pathologies, diabetes mellitus or toxicosis in the expectant mother. Even more dangerous is a too low level of hCG - this is a sign of an ectopic pregnancy, the threat of spontaneous miscarriage, placental insufficiency and even fetal death.
PAPP analysis is performed only in the first trimester of pregnancy. Its decrease indicates the presence of chromosomal abnormalities in the fetus, the possibility of Down syndrome, Edwards, Cornelie de Lange, and the threat of miscarriage. This analysis is very sensitive to the gestational age, so a mistake in setting a deadline even for a week can lead to an incorrect diagnosis.
It should be borne in mind that the results may turn out to be distorted due to some more reasons. For example, if the mother is overweight, the readings often exceed the norm, and if they are too thin, on the contrary, they are too underestimated. It is also difficult to calculate the risk of pathologies in multiple pregnancies or in vitro fertilization (IVF). Even such an insulting oversight as breakfast before donating blood can become the reason for an incorrect analysis.
