Course Advanced learning material about the challenges of human reproductive medicine in a changing Europe for OB/GYN residents

2021-1-HU01-KA220-HED-000027613 - COHRICE

TEACHERS GUIDE

Challenges of the ultrasound examinations during pregnancy 

(Advanced level)

Slide 2.: the list of available imaging methods during pregnancy, among which ultrasound is the “gold standard”.

Slide 3-4.: explains the basic physics behind ultrasound imaging. The 220 V alternating current (A/C) results shaking effect between the crystals within the transducer (piezoelectric effect), leading to ultrasound wave emission. They are then absorbed and reflected based on the water content of the organs in focus. During this process the soundwave frequency will also undergo changes, the reflected soundwaves are picked up again by the transducer and the computer creates a 2-D image on a grayscale. These waves can be continuous, or pulse -waves, which can be used for organ visualization, or vessel flowmetry analysis.

Slide 5.: explain the advantages of ultrasound, and why is it the gold-standard of imaging during pregnancy.

Slide 6-7.: There are two main examinations carried out nowadays. First is a screening ultrasound (defined at the slide), and second the diagnostic ultrasound examination (explained later).

Slide 8.: You should emphasize, that ultrasound is a technique with limitations, and never will be 100% sure in anything. It provides valuable information on basic anatomy, and some organic functions (heart, kidney), but cannot assess for instance brain functions, or metabolic procedures.

Slide 9.: explain in detail the current challenges of ultrasound. Beside the previously mentioned limitations, there are also breakthroughs in ultrasound development, such as cervical length measurement and internal cervical os funneling assessment in order to predict preterm delivery. On the other hand, since fat tissue is a poor conductor of the ultrasound waves, widespread maternal obesity can propose difficulties during the examinations, or fetal position, or fetal descent deeply into the bony pelvis blocks the appropriate measurement.

Slide 10.: list of currently recommended screening examinations during pregnancy and their timing should be discussed.

Slide 11.: elaborate these conditions, especially mention the definition of missed abortion (diminished vital signs of the embryo, without the actual expel of the pregnancy related tissues, which can be symptomless, or accompanied by bad taste in the mouth, and lack of warning signs of pregnancy), and blighted ovum (anembryonic pregnancy - early embryo never develops or stops developing, is resorbed and leaves an empty gestational sac).

Slide 12.: highlight the importance of first trimester scan. For more details check out:
https://www.isuog.org/static/uploaded/4daa1ea7-bc64-4c24-b81b17df5a684a38.pdf

Slide 13.: elaborate how gestational age is calculated based on the last menstrual period, and how can be determine the gestational age in early pregnancy with the determination of the CRL with ultrasound.

Slide 14-15.: discuss which brain structures can be examined during the first trimester scan.

Slide 16-17.: reveal the importance of nuchal translucency measurement. For how the measurement should be carried out check out:
https://nuchaltrans.edu.au/documents/protocols-for-measuring-the-nt

Slide 18.: As an additional measurement to NT determination, the IT measurement is very useful, since it augments the scan. What it is, how should be measured need to highlighted here.

Slide 19.: RNT measurement is dedicated to assessing the presence of palatoschisis, which is a major congenital anomaly, which need to be surgically corrected after birth.

Slide 20.: highlight the importance of second trimester scan. This examination is normally the final chance to detect the possible presence of major congenital anomalies, before passing the laws restricted margin between livebirth and medical conditions based induced abortions. For more details check out:
https://www.isuog.org/static/uploaded/fdae60c8-4825-46d3-924df9b8d39d5582.pdf

Slide 21-25.: the ISUOG checklist helps examiners to carry out a detailed examination, and lists what should be screened. Since all visible structures are mentioned on the list the human error is minimalized.
Slide 26.: highlight the importance of the third trimester scan. At this point, in all European countries we passed the artificial margin between livebirth, and abortion. Therefore, if late occurring anomalies are detected the pregnancy can not be aborted, rather induction of labor might be necessary.

Slide 27.: For the assessment of the intrauterine fetal development the estimated birth weight should be determined, by establishing the biophysical profile. Then it can be match with large number databases (like Headlock, etc), the fetus can categorize to be normal, small, or large for gestational age.

Slide 28.: the elaborate what preterm delivery is, and what complications can arise for a preterm neonate (ARDS, intracranial bleeding, mental retardation, obliterative retinopathy, necrotising enterocilitis, etc), which is why important to avoid preterm delivery and to detect early signs of it. Cervical lengths measurement provides this reason.

Slide 29.: in high-risk patient, especially those who underwent prior c. sections a late third trimester scans should be carried out, during which the listed structures can be scanned.

Slide 30-39.: these slides reveal the how circulatory changes inside the vessels can be measured based on the Doppler principle. Highlight the importance of the umbilical artery measurements, in order to assess the fetal well-being, and distress, while other vessel, like the ductus venosus can not only used for these purposes, but it works a warning sign for potential congenital anomalies.
Explain what the bran-sparring effect is during intrauterine fetal hypoxia, and how the redistribution of fetal circulation can be detected with ultrasound (MCA velocimetry). In case of reverse flow in the umbilical arteries fetal demise is expected within 48 hours, therefore pregnancy termination is necessary.

Slide 41-54.: reveals the most common congenital anomalies briefly. The fetal brain should be examined in three planes. If everything is found to be normal in these planes, we can exclude major CNS anomalies. The neural tube defects and their detection should be discussed, while in case of microcephaly mention the recently investigated Zika virus outbreak and correlation.
Other common anomalies include the failure of the closing of the abdominal wall. The difference between omphalocele and gastroschisis should be elaborated.
Fetal heart anomalies should be examined in the so called four chamber view, the right and left ventricular outflow tracts should be checked for abnormalities. If these are found to be normal, we can almost exclude all congenital heart anomalies.
Urinary tract anomalies and transient anomalies should be mentioned briefly.

Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the Foundation for the Development of the Education System. Neither the European Union nor entity providing the grant can be held responsible for them.