Screening and Prenatal Diagnosis

Screening and Prenatal Diagnosis

The contemporary obstetric care includes non-invasive screening procedures and invasive approaches for specific prenatal diagnosis. This paper explores the various types of prenatal screening

First Trimester Prenatal Screening

This screening employs a combination of maternal blood and ultra-sound testing. Screening for abnormalities at this stage aids to determine the risk of the fetus undergoing through birth defects such as Down's syndrome (Dungan, 2015).  Ultrasound tests for fetal nuchal translucency (increased fluid or thickening). Other tests involve screening for two maternal serum, Plasma protein and Human chorionic gonadotropin (hCG) hormone (Kapoor, Gupta, & Kabra, 2014). At this stage, if the results are of abnormal nature, the test will then require genetic counseling.

Second/ mid-Trimester Prenatal Screening

The tests are usually carried out between the 15th and 20th weeks of pregnancy (Kapoor, Gupta, & Kabra, 2014). This screening primarily includes some blood tests known as multiple markers.  The markers provide information on the probability of the fetus developing certain birth defects or the threat of the infant being born with particular genetic conditions. Multiple markers include Alpha-fetoprotein screening (AFP), hCG, Inhibin, and Estriol (Cuckle, 2014). In a situation whereby abnormal results are obtained from the AFP tests, other markers are performed for additional testing. Specifically, the medics may perform an amniocentesis for accurate diagnosing. Multiple markers are not entirely accurate and hence the screening cannot be termed as diagnostic. Nonetheless, with a combination of screening of the first and second trimesters, the ability of the screening to detect a defect is higher than just testing independently (NHS, 2014). For instance, Down's syndrome is detected after both first and second-trimester screening.

Third Trimester Screening

These tests involve screening for the presence of Group B Streptococcus (GBS), a bacterium that is generally not harmful to the woman but fatal to newborns who are yet to develop a robust immune system.

Ultrasound Scan

An ultrasound test is performed to determine pregnancy dates and to scrutinize fetal spine and potential defects in other parts of the body. Additionally, this scan determines the number of fetuses, identifies a miscarriage or ectopic pregnancy, examines the uterus, assists in other prenatal tests, ascertains the level of amniotic fluid, and generally monitors the development of a fetus (Cameron & Moran, 2014).

In summary, most of the prenatal screening is performed to expectant mothers to verify the health and development of the fetus. Most of the tests (majorly non-invasive) are undertaken in first and second tri-semesters. Prenatal screenings are regarded as routine procedures and help contain and improve maternal and infant health.

References

Cameron, M., & Moran, P. (2014). Prenatal screening and diagnosis of neural tube defects. Prenatal Diagnosis, 29(4), 402-411. doi:10.1002/pd.2250

Cuckle, H. (2014). Prenatal Screening Using Maternal Markers. Journal of Clinical Medicine, 3(2), 504-520. doi:10.3390/jcm3020504

Dungan, J. S. (2015). Medical Reasons for Pregnancy Interruption: Chromosomal and Genetic Abnormalities. Prenatal and Preimplantation Diagnosis, 49-66. doi:10.1007/978-3-319-18911-6_3

Kapoor, S., Gupta, S., & Kabra, M. (2014). Prenatal screening: Perspective for the pediatrician. Indian Pediatrics, 51(12), 959-962. doi:10.1007/s13312-014-0540-7

NHS. (2014). Your guide to screening tests during pregnancy. NHS Health Scotland, 3. Retrieved from https://www.dsscotland.org.uk/wordpress/wp-content/uploads/2015/06/NHS-Flyer.pdf