PRENATAL DIAGNOSIS Prenatal diagnosis Many techniques are available

PRENATAL DIAGNOSIS

Prenatal diagnosis Many techniques are available to assess the growth and developmental status of the fetus, including Ultrasound Maternal serum screening Amniocentesis Chorionic villus sampling(CVS)

Ultrasonogrphy Is a relatively noninvasive technique that uses high frequency sound waves reflected from tissues to create images. This approach may be transabdominal or transvaginal. Transvaginal ultrasound producing images with high resolution. Important parameters revealed by ultrasound include Fetal age and growth Presence or absence of congenital anomalies Amount of amniotic fluid Placental position and umbilical blood flow Number of gestation

Fetal age and growth are assessed by crown –rump length during the 5 th to the 10 th weeks of gestation. After that , a combination of measurements-including the biparietal diameter (BPD) of the skull, femur length, and abdominal circumference are used. Multiple measurements of these parameters over time improve the ability to determine the extent of fetal growth. Congenital malformations that can be determined by ultrasound are; Neural tube defects, anencephaly and spina bifida Abdominal wall defects, such as omphalocele Heart and facial defects, including cleft lip and palate.

Ultrasound can also be used to screen for Down syndrome and some other chromosome-related abnormalities through a test called nuchal translucency. This test involves measurement of the translucent space at the posterior of the baby’s neck, where fluid accumulates when Down syndrome and some other abnormalities are present. The test is performed at 11 to 14 weeks of pregnancy. Information from this test, combined with maternal serum screening test results and the mother’s age.

Maternal Serum Screening One of the first of these tests assessed serum a-fetoprotein (AFP) concentrations. AFP is produced normally by the fetal liver, peaks at approximately 14 weeks, and “leaks” into the maternal circulation via the placenta. Thus, AFP concentrations increase in maternal serum during the second trimester and then begin a steady decline after 30 weeks of gestation. In cases of neural tube defects, omphalocele, bladder exstrophy, and other congenital malformations, AFP levels increase in amniotic fluid and maternal serum.

In other instances, AFP concentrations decrease, as, for example, in Down syndrome, trisomy 18, sex chromosome abnormalities, and triploidy. AFP screening, combined with testing other second trimester markers (e. g. , human chorionic gonadotropin (HCG), unconjugated estriol, and inhibin A) can increase the detection rate for birth defects using these serum screening studies.

Amniocentesis During amniocentesis, a needle is inserted trans abdominally into the amniotic cavity (identified by ultrasound) and approximately 20 to 30 m. L of fluid is withdrawn. Because of the amount of fluid required, the procedure is not usually performed before 14 weeks’ gestation. The fluid itself is analyzed for biochemical factors , such as AFP and acetylcholinesterase. In addition, fetal cells, sloughed into the amniotic fluid, can be recovered and used for metaphase karyotyping and other genetic analyses.

Chorionic Villus Sampling(CVS) CVS involves inserting a needle transabdominally or transvaginally into the placental mass and aspirating approximately 5 to 30 mg of villus tissue. Because of the large number of cells obtained, only 2 to 3 days in culture are necessary to permit genetic analysis.

The risk of procedure-related pregnancy loss from CVS when performed by experienced individuals appears to approach that of amniocentesis. Previously, invasive procedures, such as aminocentesis and CVS, were offered only to women at higher risk. In recent years, risks associated with these procedures have decreased and, consequently, these procedures have been made more widely available.

Factors that place women at high risk include the following: ● ● Advanced maternal age (35 years and older); Previous family history of a genetic problem, such as the parents having had a child with Down syndrome or a neural tube defect; ● The presence of maternal disease, such as diabetes; An abnormal ultrasound or serum screening test. ●

Fetal therapy Modern medicine has also made the fetus a patient who can receive treatment, such as; Fetal Transfusion In cases of fetal anemia, or other causes produced by maternal antibodies , blood transfusions for the fetus can be performed. Fetal Medical Treatment Fetal Surgery Stem Cell Transplantation and Gene. Therapy

THANK YOU