3D/4D ultrasound
III. trimester
Screening for growth retardation of the foetus and examination of flows
Generally
We perform ultrasound screening of early inter-uterine growth retardation (early IUGR) of a foetus between the 28th and 32nd weeks and later inter-uterine growth retardation (late IUGR) after the 32nd week of pregnancy.
- growth and weight of the foetus
- amount of amniotic fluid
- prietoky v srdcovocievnej cirkulácii plodu a medzi maternicou a placentou
- position and state of the placenta
- movements of the foetus
- additional diagnosis, or monitoring of congenital defects
When?
Skríning rastovej retardácie plodu a vyšetrenie prietokov je najlepšie podstúpiť už na začiatku tretieho trimestra tehotenstva (28-32 týždeň gravidity). Výsledok tohto vyšetrenia pojednáva o stave plodu, vyhodnocuje jeho rast a prietoky krvnej cirkulácie, ktoré poukazujú na možné hypoxické ohrozenie plodu a riziko preeklampsie. V skratke toto vyšetrenie hodnotí “ako dobre sa má plod” (fetal well being scan) a či existuje pre pacientku zvýšené riziko preeklampsie (pôvodne gestóza). Tento typ ultrazvukového vyšetrenia sa v prípade podozrenia na závažné ohrozenie plodu vykonáva už pred 20 týždňom gravidity.Genetický ultrazvuk realizujeme medzi 18 až 20 týždňom tehotenstva, daná limitácia týždňov je viazaná k záchytu jednotlivých sonografických markerov a pre prípadnu časovú možnosť genetického vyšetrenia, buď analýzou NIPT (PRENASCAN) alebo plodovej vody – amniocentéza (AMC).
How?
We carry out the examination most often with an abdominal USG probe. During the examination the patient lies on her back or turned slightly on her left side, thus reducing the risk of vena cava inferior syndrome.
What is it for?
with calculation of its estimated weight relevant to the week of pregnancy and projection to a current percentile graph. We focus on a foetuses with insufficient growth, which are under the 10th percentile on the growth graph for the given week of pregnancy. These make up 10% of the group of all foetuses and together they are labelled as “Foetal Growth Restricted - FGR”. It is FGR foetuses that require increased monitoring. More than 30% of FGR foetuses are affected by so-called Intrauterine Growth Restriction – IUGR. An IUGR foetus is significantly endangered by birth and pre-birth mortality and morbidity due to long-term haemodynamic adaptation. This arises especially in consequence of an insufficient placenta, which we register by measuring flows. Subsequently, a metabolic adaptation of the foetus develops due to the mentioned changes and the “foetus doesn’t awake and its growth slows.” The purpose of the screening for growth retardation is to capture and monitor IUGR foetuses which are, compared with appropriate for gestational age (AGA) foetuses, endangered to a higher measure by:
- intrapartum asphyxiation
- new-born hypoglycaemia and hypocalcaemia
- aspiration of the meconium
- late psychomotor development
- haemodynamic instability, which leads to right-side heart failure
which enables the assessment of the functional state of the foetus in the uterus. The first reaction of a foetus to a lowered input of nutrients from the placenta is a lowering of the metabolic needs of the foetus, which leads to a slowing of growth. At the same time flow is increased in the cerebral stream, which is the first flow sign of compensation. Cerebral flow achieves a maximum perhaps two weeks prior to the start of slowing of heart frequency. But the redistribution of changes in circulation of a foetus continues up to birth. With reduced input of oxygen and nutrients from the placenta, the foetus with the help of blood circulation redistribution ensures sufficient arrival of oxygen and nutrients to the brain, heart muscles and adrenal glands. While the foetus is capable due to this compensation mechanism to preferentially ensure oxidation of the myocardia, it is not able to develop the right side of the heart. Therefore, the majority of foetuses in which Doppler metric measurement demonstrates arterial redistribution with normal venal flow has in this phase normal, reactive heart activity curves during cardiovascular examination – CTG. Doppler metric measurement, compared with CTG examination, is capable of pointing to distress of the foetus up to four-weeks in advance. Examination of flows consists of Doppler metric assessment of the blood vessels of the uteroplacental (uterine arteries – AUt) and the foetal (umbilical blood vessels – AU and VU, middle cerebral artery – MCA, the aortal isthmus – AoI and the ductus venosus - DV) circulation.
pre objektivizáciu slúži stanovenie jej indexu AFI – Amniotic Fluid Index. Index vyjadrený v dĺžkových jednotkách centimetroch (cm) vyhodnocuje veľkosť štyroch najväčších priestorov s plodovou vodou v štyroch určených maternicových lokalitách. Táto metóda umožňuje porovnanie množstva plodovej vody s odstupom času. Pokles indexu množstva plodovej vody môže signalizovať plod v kompenzácií alebo pod stresom, ktorý sa prejaví ešte skôr ako zmeny pri kardiotokografickom non-stress teste (CTG/NST). U IUGR plodov sa daný index môže znižovať náhle alebo pomaly.
during which we determine its localization, structure and degree of “maturation”. With growth retardation of the foetus we evaluate the volume of the placental tissue, because IUGR of the foetus shows in terms of volume about 25% smaller placenta than a normal foetus. Likewise, placenta circumvallata, placenta membranacea and a placenta with chorangiomatosis occur in a higher measure in these foetuses. The most significant cause of development of IUGR is insufficient placenta tissue, especially abnormal changes in the terminal villous compartment.
we examine and determine these with each ultrasound examination. We conduct a more detailed focusing on the types of movements with evaluations of a biophysical profile of the foetus using 2D eventual 3D/4D modes. Experimental examination of foetal movements using the KANET test (3D/4D sonography) can help with identification of the disability of a foetus with children’s cerebral palsy.