Nuchal Translucency Thickness as Method of Screening during 10-13 weeks of pregnancy

Nuchal Translucency Thickness as Method of Screening during 10-13 weeks of pregnancy

Nuchal translucency thickness (NT) denotes a standard fluid-filled subcutaneous space located between the back fetal skin and the overlying skin. Since nuchal translucency is visible, it can be measured through the use of ultra-sonographic imaging. It is useful during the 10-13 weeks of the gestation period. According to research, escalating NT is linked to various fetal chromosomal and non-chromosomal abnormalities. Research has also demonstrated that there is rising evidence that raises the NT thickness during the 10-13 weeks of pregnancy, especially in a fetus with normal chromosomes. During such conditions, the fetus tends to show many fetal structural abnormalities, defects of the heart, and genetic syndromes. There are also associated with perinatal outcomes, which include the miscarriage and intrauterine death.

The research was done by Sharifzadeh et al. 2015, many studies from different parts of the world have engaged in the determination of the normal range of NT based on varied populations. After the introduction of NT thickness, its utility has been considered as a sensitive and noninvasive ultrasonography approach. It is used in the screening and detection purposes of aneuploidies and other structural abnormalities during pregnancies. Therefore, many developed countries have been in the position to adopt it as a primary method for screening pregnancies during the ten weeks. To ascertain their research hypothesis, the research of the article “Normal reference range of fetal nuchal translucency thickness in pregnant women in the first trimester, one center study” utilized an analytical cross-sectional study, and they referred pregnant women for screening to a private radiology center. The women were advised to undertake an ultra-sonographic screening while attending to their antenatal visit, especially in their first trimester. According to the authors, the study was conducted from January 2013 to December 2013 in Isfahan, Isfahan province of Iran (Sharifzadeh et al., 2015). The majority of those who undertook the screening were women with pregnancy age of 10-11 weeks and with CRL 45-84mm.  An expert radiologist conducted the task of sonography.

The radiologist then measured the fetal NT thickness of the screened women. The research found out that the reference 95^th percentile value range for NT was 1.8-2.35 and raised NT thickness based on the obtained values, which were considered having chromosomal abnormalities. Thus, the research ascertains that the NT thickness is crucial in screening various abnormalities associated with non-chromosomal and chromosomal abnormalities.

Because the chromosomal abnormalities can produce impaired cardiovascular development, a nuchal translucency scan is utilized as a screening instead of using the diagnostic methods. The NT can determine the nuchal translucency as well as the thickness associated with the nuchal fold. It means that nuchal translucency size can easily be determined at the end of the first trimester (from 10-13) weeks of pregnancy. Accordingly, as the size of nuchal translucency rises, the chances of developing abnormality in chromosomal conditions also escalate. That, in turn, increases the fatal mortality rate. For instance, 65% of the biggest translucencies (more than 6.5mm) are a result of chromosomal abnormalities (Sharifzadeh et al., 2015). The nuchal scan is crucial in that it assists physicians in determining the risk of the fetus developing Down syndrome condition or even other abnormalities during the pregnancy period.

Park et al. (2016), through the research “Screening for chromosomal abnormalities using the combined test in the first trimester of pregnancy,” undertook a prospective screening study for evaluation of the adoption and implementation of additional ultrasound examination. The research was essential in that it determines how ultrasonographic imaging can be used for determining the fetal nuchal translucency thickness at the gestation period of women during the 10 to 13 weeks period (Park et al. 2016). According to the research, the maternity units in different healthcare institutions can undertake the NT screening while performing the routine antenatal care for pregnant women. The authors further argued that the essential factor that indicates fetal karyotyping is the maternal age. Therefore, in 10-13 weeks, women visiting hospitals should undergo evaluation of fetal nuchal translucency thickness.  That would assist in determining the possibility of a fetus developing abnormalities and can be corrected earlier.

Nuchal translucency (NT) scan is undertaken during the 10-13 weeks of pregnancy since it is a viable stage for obtaining the accuracy of chromosomal abnormalities. While performing the procedure, the sagittal section and neutral position of the fetal head is scanned. However, the fetal image ought to be enlarged to occupy 75% of the screen to ensure accurate measurement of the maximum nuchal translucency thickness. When there is a rise in the nuchal transparency, there is a high probability that abnormalities will impact the fetus in the chromosomal conditions. Also, it indicates that the fetus can be affected or may develop cardiac defects, the intrauterine fetal demise, and congenital cardiac conditions (Park et al. 2016). The use of Nuchal translucency thickness over the previous methods is advantageous in that results in the reduction of false-positive ratings during the trimester of the gestation period.

According to Wright et al. (2015), in their article “A unified approach to risk assessment for fetal aneuploidies,” NT majorly increases with the gestation period (known as the crown-rump length). A fetus having a particular crown-rump length, the NT measurements are used as a representation of a likelihood ratio, which is mostly multiplied by a priori gestation and maternal age-related risks. While conducting the procedure, a new threat to the fetus can easily be determined and appropriately contained (Wright et al. 2015). Accordingly, the higher the NT, the larger the likelihood ratio develops, thus, indicating higher chances of a new risk. Comparatively, when the NT is small, the likelihood of developing a fetal risk is minimal, and that means the probability of developing a new threat is low. The author deduced that modern medicine should emphasize the nuchal translucency thickness scan. That would prevent fetal mortalities, which were rampant before the advent of approach. Accordingly, that would improve the medical field and save fetus lives, which could occur.

Chromosomal abnormalities have been considered the major causes of perinatal mortalities across the world. Therefore, when proper screening of pregnant women is not conducted during their trimester pregnancy periods, it can result in the development of abnormal conditions before and after the child is born. The primary goal of undertaking prenatal testing is to screen for possibilities of abnormalities in fetal chromosomal conditions. When that has been tested, proper counseling to the parents is provided. To effectively attain that, the nuchal translucency as a method of screening is appropriate during the 10-13 weeks of pregnancy. According to Park et al. (2016), the American College of Obstetrics and Gynecology has recommended that prenatal care be administered among all pregnant women. One of the methods that should be utilized is the nuchal translucency thickness, among other invasive genetic screening methods such as chorionic villi sampling methods. Wright et al. (2015) also argue that when first-trimester of pregnancy should combine maternal age, fetal nuchal translucency thickness (NT) tests for screening for trisomies 12, 18, and 13 it ensures achievement of around 90% of the impacted pregnancies at the false-positive rate (FPR). With that, the healthcare workers providing antenatal care to pregnant mothers will be in the position to monitor the gestation period positively.

Conclusively, the nuchal translucency thickness (NT) is an essential method for screening pregnant women at 10-13 weeks period. It is a crucial method for appropriately testing fetal chromosomal conditions. When chromosomal abnormalities are not detected during fetal development, it will result in problems during the delivery or after the baby has been borne. Therefore, the paper explored the usability of nuchal translucency thickness (NT) as a method for screening during the 10-13 weeks of pregnancy. Accordingly, the NT method is essential since it provides an opportunity to determine the chromosomal abnormalities shown by the fetus. When that has been established, the healthcare workers providing antenatal care are in the position to advise the mothers appropriately. The method is also crucial since it enables the medical personal to correct the chromosomal abnormalities and other fetal abnormalities early. That will ensure the delivery of a healthy fetus, thus, reducing the fetal mortalities. Previously, the fetal abnormalities have been impacting the quality of life of borne children. Therefore, with the adoption and utilization of the NT method for screening during the 10-13 weeks of pregnancy, such problems will be reduced.

References

Sharifzadeh, M., Adibi, A., Kazemi, K., & Hovsepian, S. (2015). Normal reference range of fetal nuchal translucency thickness in pregnant women in the first trimester, one center study. Journal of research in medical sciences: the official journal of Isfahan University of Medical Sciences, 20(10).

Park, S. Y., Jang, I., Lee, M. A., Kim, Y. J., Chun, S. H., & Park, M. H. (2016). Screening for chromosomal abnormalities using a combined test in the first trimester of pregnancy. Obstetrics & gynecology science, 59(5).

Wright, D., Wright, A., & Nicolaides, K. H. (2015). A unified approach to risk assessment for fetal aneuploidies. Ultrasound in Obstetrics & Gynecology, 45(1).

Kagan, K. O., Wright, D., & Nicolaides, K. H. (2015). First‐trimester contingent screening for trisomies 21, 18, and 13 by fetal nuchal translucency and ductus venosus flow and maternal blood cell‐free DNA testing. Ultrasound in Obstetrics & Gynecology, 45(1).

Messerlian, G. M., Farina, A., & Palomaki, G. E. (2019). First-trimester combined test and integration tests for screening for Down syndrome and trisomy 18. Louise Wilkins-Haug M, Vanessa A, Barss M, editors. UpToDate: UpToDate, Post TW (Ed), UpToDate. Waltham. Accessed Feb 4, 2018.

Alanen, J., Leskinen, M., Sairanen, M., Korpimaki, T., Kouru, H., Gissler, M., & Nevalainen, J. (2019). Fetal nuchal translucency in severe congenital heart defects: experiences in Northern Finland. The Journal of Maternal-Fetal & Neonatal Medicine, 32(9).

Lund, I. C. B., Christensen, R., Petersen, O. B., Vogel, I., & Vestergaard, E. M. (2015). Chromosomal microarray in fetuses with increased nuchal translucency. Ultrasound in Obstetrics & Gynecology, 45(1).

White, K., Schmid, M., & Kostenko, E. (2019). OP05. 10: A global landscape analysis of reimbursement policies for prenatal cell‐free DNA testing in public healthcare systems. Ultrasound in Obstetrics & Gynecology, 54.