PROfeSSOR Drhind showman definition Prenatal diagnosis is the identification of a disease in the fetus prior to birth is the procedures undertaken to diagnose genetic abnormalities and structural ID: 1000098
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1. Prenatal diagnosis Assistant PROfeSSOR Dr.hind showman
2. definitionPrenatal diagnosis is the identification of a disease in the fetus prior to birth. is the procedures undertaken to diagnose genetic abnormalities and structural anomalies
3. Indications of prenatal diagnosis:.Family history of single gene disorder , neural tube defectAbnormalities identified in pregnancy.women with previous miscarriage..Past obstetrical history –Rh alloimmunization.Abnormal serum screening test result-trisomy 21.ultrasound screening-20 weeks anomaly scan.Advanced maternal age . Multiple pregnancy losses (>3). High risk factors like consanguinity, poor obstetric history, maternal illnesses .chronic drug use
4. Benefits:Malformation incompatible with life may be terminated.Certain abnormalities may be correctible in-utero.-Provides opportunity to arrange corrective measures - offer a chance to be delivered at a place where the required facilities are available.4. Parents decision to continue pregnancy/ mentally prepare to have a handicapped child.
5. classificationPrenatal diagnostic tests can be divided into non-invasive tests and invasive tests.The main non-invasive test is the use of ultrasound scanning to screen for structural fetal abnormalities, such as neural tube defects, gastroschisis, cystic adenomatoid, malformation of lung, renal abnormalities
6. Non- Invasive procedures1.Ultrasound It is different from screening Us.It takes longer time, diagnose wide range of chromosomal anomalies, 1.Major Structural Defects- Cystic hygroma, Nonimmune hydrops,.2.-First-Trimester Nuchal Translucency:-The increased sonolucent area at the back of the fetal neck. Is carried out at 11–13+6 week's Increased is related to dilated lymphatic channels, itself is not a fetal abnormality..
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8. Conditions associated with increased nuchal translucency: - Down syndrome-Cardiac defect.-Diaphramatic hernia.-Exomphalos.-Achondroplasia.
9. Cleft lip and palate
10. 2.maternal blood markers:1.Free β-HCG:is increased in fetuses affected with trisomy 21.2.PAPP-A( pregnancy associated plasma protein –A )is decreased in fetuses affected with trisomy 21.3. maternal serum alpha-fetoprotein(MSAFP).4. un-conjugated estradiol ,inhibin-alpha
11. Second Trimester screening(Maternal analytescreening) :Triple screening1.Alpha feto protein.2.HCG3. un-conjugated estradiol
12. Maternal blood can be tested for exposure to viruses (viral serology). If a woman has no immunoglobulin (Ig) G or IgM for a particular virus early in pregnancy, but then develops IgM and IgG later in pregnancy, it suggests that she has had a clinical or subclinical infection with that virus earlier during pregnancy
13. Examples of conditions and their method of diagnosisUltrasound diagnosisNeural tube defectGastroschisisCystic adenomatoid malformation of lungTwin-to-twin transfusion syndrome Invasive test – CVS or amniocentesisDown’s syndromeCystic fibrosisThalassaemia Invasive test – cordocentesis Alloimmune thrombocytopaeniaUltrasound then invasive testCongenital diaphragmatic herniaExomphalosVentriculomegalyDuodenal atresia
14. Abnormal maternal alpha fetoprotein level :Low levelHigh levelObesityUnderestimated gestational ageDiabetesMultifetal gestationChromosomal trisomies Neural-tube defectsdiseaseGestational trophoblastic diseaseOmphaloceleFetal deathGastroschisis
15. Classification of Congenital AbnormalitiesChromosomal Abnormalities: - Trisomy 21 (D.S) - Trisomy 18 (E.S) - Trisomy 13 (P.S) Structural Abnormalities: - CNS - CVS - GIT - Bone - Renal systemGenetic Disorders: - Inborn error of metabolism - Haemoglobinopathies
16. Invasive procedureChorion villus sampling (also known as chorion villus biopsy)Fetal trophoblast cells in the mesenchyme of the villi divide rapidly in the first trimester. A CVS procedure aims to take a sample of these rapidly dividing cells from the developing placenta. This is done either by passing a needle under ultrasound guidance through the abdominal wall and myometrium into the placenta or by passing a fine catheter (or biopsy forceps) through the cervix into the placentaTransabdominal procedures are performed more commonly, but they may not be feasible if the uterus is retroverted or the placenta is low on the posterior wallof the uterus.
17. The woman is scanned initially:To confirm that the pregnancy is viable prior to the procedure.To ensure that it is a singleton pregnancy (prenatal diagnosis in multiplepregnancy is more complex).To confirm gestational age (CVS should not be performed before 10 weeks’ gestation).To localize the placenta and determine whether a transabdominal or transcervical approach is more appropriate
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20. Indications:1.detects chromosome abnormalities (i.e. Down syndrome) and genetic disorders (i.e. cystic fibrosis.). 2. provides access to DNA for paternity testing prior to delivery.
21. Complications:Risk of miscarriage is 2%. it compared to amniocentesis is that it may be associated with a higher risk of miscarriageamnionic fluid leakage or infection is < 0.5 %.
22. Relative contraindications :-vaginal bleeding or spotting.-active genital tract infection.-extreme uterine ante- or retr oflexion.-body habitus precluding easy uterine access or clear sonographic visualization of its contents
23. AmniocentesisAmniotic fluid contains amniocytes and fibroblasts shed from fetal membranes,skin and the fetal genitourinary tract. An amniocentesis procedure takes a sample(15–20 ml) of amniotic fluid that contains these cells. This is done by passing aneedle under continuous direct ultrasound control through the abdominal wall andmyometrium into the amniotic cavity and aspirating the fluid
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25. An initial ultrasound is performed prior to the procedure. The estimated total postamniocentesis pregnancy loss is 1.9% for a procedure performed from 15 weeks of gestation under ultrasound guidance.
26. -Because the initial 1 or 2 mL of fluid aspirate may be contaminated with maternal cells, it is either discarded or used for amnionic fluid AFP testing. Another approximately 20 mL of fluid is then collected for fetal karyotyping, and the needle is removed.-Sonographically the uterine puncture site is observed for bleeding, and fetal cardiac motion is documented at the end of the procedure
27. -Indications :1.Maternal age ≥ 35 years at the time of delivery with a singleton pregnancy .2.Parent or previous child with chromosomal abnormality 3. Both parents carriers for a recessive disorder or an autosomal dominant disorder diagnosable by amniotic fluid analysis 4.Mother a carrier for an X-linked recessive disorder diagnosable by amniotic fluid analysis .5. Parent or previous child with a neural tube defect 6.Elevated maternal serum alpha-fetoprotein 7. Multiple marker screening test indicating increased risk of Down syndrome or trisomy 18
28. Complications-transient vaginal spotting .-amnionic fluid leakage in 1-2% -chorioamnionitis < 0.1 %. -Needle injuries to the fetus are rare. -Fetal cells obtained during amniocentesis rarely fail to grow in culture. However, this is more likely if the fetus is abnormal . fetal loss ≈0.5 5%
29. 3. Fetal Blood Sampling(cordocentesispercutaneous umbilical blood sampling (PUBS):-A 22-gauge spinal needle is passed under ultrasound guidance into the umbilical cord to puncture the umbilical vein.-at a point where it inserts into the placenta because the umbilical cord is fixed and does not move-Performed from about the 20 weeks gestation
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31. indications1.it is performed when fetal blood is needed, or when a rapid full culture for karyotyping is needed.2.Check the fetal platelet count , when alloimmune thrombocytopenia is suspected.3.diagnosis of fetal infection.4.determination of fetal Rh(D) status 5.some direct fetal therapy via the fetal umbilical vessels.
32. Complications:-The risk of miscarriage is 2-5 %.-cord vessel bleeding .-cord hematoma. -fetal-maternal hemorrhage 66 % with an anterior placenta and 17 % with a posterior placenta -fetal bradycardia
33. Down's syndrome:-The most common reason for performing prenatal invasive testing .-Recommended that all women should be offered screening for down's as part of there routine antenatal care.
34. Combined tests should be performed between 11-14 weeks gestation , involves the combination of an US to measure NT + blood tests to measure the levels of HCG and the PAPP-A in the maternal plasma Free ßhCG higher in Down’s Pregnanciesduring 1st trimester screening period. Protein-A. Placental protein which continues to increase during the term of the pregnancy Serum levels lower in Down’s pregnancies in 1st trimester screening period
35. incidence of Down’s SyndromeDown’s Syndrome and maternal age 24 1 in 95030 1 in 68036 1 in 21042 1 in 40
36. Double or triple test?uE3 – very unstableinterfere of lipaemiadifferent quality of diagnostics setsgrowth of positivity don‘t comport withrecoverylong-term comparision showedirresponsibility results of triple test in ourconditions
37. exact gestational dating is essential to calculate risk of DS– measured value standardised against expected median value for a normal population at same stage of gestation– DS fetuses are relatively retarded compared to normal– results in alteration of maternal serum concentration of foetalproducts e.g AFP, hCG– serum concentrations related to gestational age
38. e.g decrease AFP, decrease hCG increaseQuadreplet testTo the above add inhibin A Increase in down syndrome