Ultrasonographic examination in the second trimester of pregnancy
Second trimester ultrasound is usually performed between 18+0 and 20+0 weeks of pregnancy. The examination is focused at structural fetal anomalies (thorough evaluation of morphology of fetal organs). Another component of the examination is evaluation of some markers associated with chromosomal defects, such as Down syndrome. The markers often represent just tiny changes of fetal morphology. To this group of markers belong measurements of nasal bones, nuchal thickness, renal pelvises, evaluation of the middle phalanx of the fifth finger of hand, etc.
In case of suspicion of a chromosomal abnormality the patients are counseled by geneticist and amniocentesis is recommended. Results of the amniocenteses are usually available in three weeks. Some special technics of processing of the sample of the amniotic fluid, (FISH - Fluorescence In Situ Hybridization, or QF-PCR - Quantitative Fluorescence - Polymerase Chain Reaction) allow to obtain results sooner, usually within two days.
Following images represent just a few examples of evaluated fetal structures during the second trimester ultrasonographic examination. To make them better understandable to general public, we added drawings to some of them.
Special 3D/4D techniques that can be used in evaluation of the fetal heart
These special techniques are not routinely used in practice and some of them are just experimental (for example representation of the fetal heart using the "Sono AVC - Sono Automated Volume Calculation" technique as it is shown on the image below). They can be used as a helpful addition to 2D imaging and enable to get better spatial projection of some cardiac anomalies. They also allow demonstrating of some imaging planes of the heart that are difficult to obtain by classical 2D ultrasonographic examination.