[Author’s Name]
[Institution’s Name]
Essay on Prenatal Assessment of Women
If all pregnant women 35 years or older chose to have amniocentesis, about 30 percent of trisomy 21 pregnancies would be detected.11 Women younger than 35 years give birth to about 70 percent of infants with Down syndrome.12 Maternal serum screening (multiple-marker screening) can allow the detection of trisomy 21 pregnancies in women in this younger age group. Alpha-fetoprotein (AFP), unconjugated estriol and human chorionic gonadotropin (HCG) are the serum markers most widely used to screen for Down syndrome. This combination is known as the "triple test" or "triple screen." AFP is produced in the yolk sac and fetal liver. Unconjugated estriol and hCG are produced by the placenta. The maternal serum levels of each of these proteins and of steroid hormones vary with the gestational age of the pregnancy. With trisomy 21, second-trimester maternal serum levels of AFP and unconjugated estriol are about 25 percent lower than normal levels and maternal serum hCG is approximately two times higher than the normal hCG level. (DIANE Publishing Company, January 2004)
The triple test is usually performed at 15 to 18 weeks of gestation. The level of each serum marker is measured and reported as a multiple of the median (MoM) for women with pregnancies of the same gestational age as that of the patient's. The likelihood of trisomy 21 is calculated on the basis of each of the serum marker results and the patient's age. A composite estimate of the risk of trisomy 21 is reported to the clinician. A standard risk cutoff is used to determine when the test is considered "positive." Most laboratories use a risk cutoff of 1/270, which is equal to the second-trimester risk of trisomy 21 in a 35-year-old woman. A positive test is an indication for amniocentesis.........
This essay has the followings:
Total words: 727
Total reference: 5
Total price: £ 9.95
Click here to Order this essay!
Get Professionally written Essays that are:
• Written According to your Exact Requirements
• 100% Original and Non-Plagiarized
• Written by Expert
UK Writers
• Delivered to you before your deadline
Amazingly Low Prices - £9.95/page
