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Prenatal diagnosis
- 1. PRENATAL DIAGNOSIS Usha Rani S. DASMAHE Nandhini Madhuri M.Sc.
- 2. Outline Introduction What is prenatal diagnosis Purpose of prenatal diagnosis Indication Methods Uses Summary
- 3. The Pre-natal Diagnostic Technique (Regulation and Prevention of Misuse). Act 1994 Revised in April 2003 The Pre-conception and Pre-natal Diagnostic Technique(prohibition of sex selection) Introduction
- 4. Prenatal diagnosis Procedures undertaken to diagnose genetic abnormalities and structural anomalies often early embryo and fetus in order to undertake timely prenatal counseling and appropriate interventions. It allows timely termination of pregnancy thereby preventing wastage and perinatal mortality.
- 6. Prenatal diagnosis Allows : timely medical treatment of a condition before or after birth parents to make decisions regarding whether to abort a fetus with a diagnosed condition parents to prepare psychologically, socially, financially, and medically for a baby with a health problem or disability. determine the outcome of pregnancy.
- 7. Indications for prenatal diagnosis Advanced maternal age Previous child with a chromosome abnormality Women who are pregnant with multiples (twins or more) Family history of single gene disorder Family history of a neural tube defect Family history of other congenital structural abnormalities Abnormalities identified in pregnancy Women who have previously had miscarriages Other high risk factors(consanguinity, poor obst., Maternal illnesses)
- 8. Methods of prenatal diagnosis Invasive Non-invasive Amniocentesis. Ultrasonography Cordocentesis. MRI CVS Cell-free fetal DNA Biopsy from fetal tissue. Triple test Coelocentesis
- 9. Amniocentesis -Performed in II trimester. trimesterZ -Widely available. -1 in 300-500 women will misc will m miscarry
- 10. Chorionic Villus Sampling Performed in 2nd trimester Specialized technique Risk same as amniocentesis
- 11. Cordocentesis Also called as PUBS Done after 18 weeks of pregnancy 2 in 100 women will miscarry
- 12. Fetal tissue biopsy Performed between 17-20 weeks gestation <1 in 1000 women shows infection
- 13. Coelocentesis Performed before 10 weeks of pregnancy Coelomic space between amniotic membrane and uterine cavity Fetal loss=0 or <that of amniocentesis
- 14. Ultrasonography Medical imaging technique that uses high frequency sound waves. It frequency range of 1-12 megahertz Developing embryo can be visualized at about 6 weeks of gestation
- 15. Magnetic Resonance Imaging MRI is combined with ultrasound usually at or after 18 weeks of gestation MRI is a risk-free method
- 16. Cell-free fetal DNA cffDNA is fetal DNA circulating freely in maternal blood stream It is sampled by venipuncture on the mother cffDNA can first be observed as early as 7 weeks gestation, and the amount of cffDNA increases as the pregnancy progresses
- 17. Triple test Also called as double test or quadruple test Triple test measure: -alpha-fetoprotein(AFP) -human chorionic gonadotropin(HCG) -unconjugated estriol(UE3)
- 18. Triple test screens for following fetal disorders
- 19. Applications of prenatal diagnosis Maternal serum screening:- Fetoprotein, estriol and HCG estimation Ultrasonography:-Structural abnormalities Amniocentesis:- Fetoprotein and acetylcholinesterase Chromosomal analysis Biochemical analysis Chorionic villus sampling:- DNA analysis Chromosomal analysis Biochemical analysis Fetal blood sampling:- Chromosomal analysis DNA analysis
- 20. Summary The commonest indication of prenatal diagnosis is advanced maternal age, family history of chromosome, single gene or structural abnormality and pregnancies with multiples The significance of most prenatal diagnostic findings is clear. It can be carried out by non-invasive procedures(MS-AFP for NTD, triple test for Downs sy., and US for structural abnormalities) Invasive procedures as amniocentesis or CVS is usually requires for diagnosis of chromosome and single gene disorders Invasive procedures convey small risk for miscarriage(0.5-1% for amniocentesis,2-3% for CVS)
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