prenatal screening ,, Off Abids Road, Bogulkunta, Hyderabad , Opp. Old MLA Qrtrs., Hyderguda, Hyderabad

Transcription

1 Department of Fetal Medicine prenatal screening UNIT 1 BOGULKUNTA ,, Off Abids Road, Bogulkunta, Hyderabad UNIT 2 HYDERGUDA , Opp. Old MLA Qrtrs., Hyderguda, Hyderabad UNIT 3 JUBILEE HILLS Plot # 769, Near MAA TV, Road # 44 Jubilee Hills, Hyderabad ALL THREE UNITS Centralized Tel. : Appointments only Tel. : Website :

2 Pregnancy is a wonderful time filled with excitement and anticipation of a new member in the family. The early weeks of pregnancy can be an exciting, but anxious time. Like most expectant mothers, you may want reassurance that your baby will be normal and healthy. We, also, are as eager as you and your family to ensure that you have a smooth pregnancy. Read on to learn more about screening for certain chromosome abnormalities and birth defects and why it is important for you to be tested early in your pregnancy. Why should I have Prenatal Testing? While most babies are born healthy, 2 or 3 of 100 newborns may have major birth defects. At various stages of pregnancy, we recommend different tests to ensure that your baby is developing normally. One such test, which is mandatory, is the prenatal screening test to check the chromosomal abnormalities of the baby. What are Chromosomal Abnormalities? All human beings have 23 pairs of chromosomes. A chromosome abnormality occurs when there are extra or missing chromosomes, or there is a rearrangement of pieces of chromosomes. Intellectual and physical development can be affected as a result of this chromosome difference. The common abnormalities include Down s syndrome, trisomy 18 and trisomy 13.

3 What is Down s syndrome? Down s syndrome, also known as trisomy 21, is the most commonly occurring chromosome abnormality. It is caused by having an extra copy of chromosome 21. The incidence of Down s syndrome is about 1 in 700 live births. Down s syndrome often results in developmental problems and a higher risk of conditions including heart defects, mental retardation, breathing and hearing problems, and childhood leukemia. The severity of these conditions varies. Counselling and support to manage a baby with Down s syndrome, is the only hope. What is Trisomy 18 and Trisomy 13? Trisomy 18 or Edward s syndrome and trisomy 13 or Patau s syndrome are comparatively rare and severe forms of chromosomal abnormality associated with severe mental and physical handicap with life threatening complications in a baby s first months and years. No treatment is available for trisomy 18 or trisomy 13. Why is Prenatal Testing Important? Tests done during pregnancy will provide information about the health of your baby, even before the baby is born. The information you receive will be extremely valuable in helping you plan for your baby s birth. All expectant mothers are at risk of having a baby with a chromosomal abnormality i.e. Down s syndrome, trisomy 18 and trisomy 13. The first trimester screening test is performed to

4 know whether your risk is increased or decreased. With expert counselling, you will be able to decide if you need further tests in pregnancy. Also, if you learn that you are going to have a baby with one of these birth defects, you can pro actively prepare your family for the future, by making important medical and financial decisions about care. International guidelines in many countries such as USA, Canada, UK, Netherlands, Spain and France, recommend that prenatal testing be offered to all pregnant women, regardless of age. How is Prenatal Screening Performed? Various methods of prenatal screening are practiced. The screening may be done in the first trimester, second trimester or in both trimesters. The screening takes into account your age, a blood test and, usually, a special ultrasound test. First Trimester Screening A popular and advantageous model of prenatal testing is the combined first trimester screening test. It involves a simple blood test done when the fetus is between 11 weeks and 13 weeks 6 days of age. The blood is analyzed for 2 markers normally found in all pregnant women. The blood test is followed by an ultrasound examination, at the same time. The ultrasound confirms your baby s age and measures the amount of fluid behind the baby s neck (Nuchal Translucency scan or NT scan). Results of the blood test and the ultrasound are combined to estimate the risk of Down s syndrome, trisomy 18 and trisomy 13.

5 About 90% of Down s syndrome cases are detected About 95% of trisomy 18 and trisomy 13 cases are detected. Second Trimester Screening If you have missed the opportunity of first trimester screening, you should have the second trimester screening. The detection rate for Down s syndrome is lower than the first trimester screening (around 65 70%) but the test also checks for Open Neural Tube Defects (Open NTD). Open Neural Tube Defects Open Neural Tube Defects (ONTD), such as spina bifida, result from improper development of the brain and spinal cord, which may cause an opening to remain along the spine or head after the baby is born. ONTDs can be detected through a maternal serum alpha-fetoprotein (MSAFP) screening. Blood is drawn from the mother s arm and sent to the lab for analysis High levels of AFP in the blood may indicate that the developing fetus is at risk of an ONTD. What do the Results of the Prenatal Screening Mean? Note : it must be clearly understood that the results represent risks and not diagnostic outcomes. Low risk : a low risk report means the baby is at low risk for Down s syndrome, trisomy 18 or trisomy 13. In such a case, further testing to rule out trisomy will not be done

6 A low risk report does not completely eliminate the possibility that the baby may have Down s syndrome, trisomy 18, or trisomy 13. High risk : such a result is received, we suggest additional diagnostic testing options, like chorionic villus sampling (CVS) or amniocentesis. Please remember, a screening test does not confirm trisomy. Hence, a high risk report should be followed by a confirmatory test. Additional Tests If you are at risk of having a baby with a birth defect based on your family history or the results of a screening test, we may recommend diagnostic testing. There are two options that may be considered. One test, known as chorionic villus sampling, or CVS, is performed at 11 to weeks of pregnancy. CVS does not test for open neural tube defects. Another test, known as amniocentesis, is performed between 15 and 20 weeks of pregnancy. Both these confirmatory tests are associated with 1 in 200 chance of risk of miscarriage. In case you have any further queries, you can meet fetal medicine experts in the counselling clinic with prior appointment. Just Remember : Most babies are born healthy. Early, more accurate screening gives peace of mind during pregnancy.