Presentation on theme: "By Dr. Shumaila Zia Assistant Professor"— Presentation transcript:
1 By Dr. Shumaila Zia Assistant Professor PRENATAL DIAGNOSISByDr. Shumaila ZiaAssistant Professor
2 Prenatal DiagnosisOver the last 4 decades, the genetic basis of an increasing number of diseases is becoming understood. At the same time, safe and effective fetal diagnostic techniques are being developed.
3 Fetal medicineOnly in the past few decades has the fetus been considered a patient and become the subject of extensive scientific study and attempts at treatment. Fetal medicine is a complex multidisciplinary undertaking with a teamFetal diagnosisFetal Therapy
4 Prenatal Diagnosis of fetal Abnormalities Benefits:Malformation incompatible with life may be terminated.Certain abnormalities may be correctible in-utero.-Provides opportunity to arrange corrective measures before hand.- 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.
6 What Should We Do?Every pregnancy should be evaluated with the most definite test.Practically & economically not feasible becauseexpensiveInvasiveWorldwide practice is to carry out-Screening procedures-Definite (diagnostic)tests for screeningpositive cases
8 Screening Procedures --- Cont. History:- Increasing maternal age- Congenital anomalies in previous children- F/Hx.. Still birth. Recurrent 1st trimester abortion. Cousin marriage
9 Screening Procedures ---Cont. 2. Features of current pregnancy: - Drug intake(antiepileptics e.g. warfarin, alcohol, smoking) - Radiation exposure - Maternal ch. diseases e.g.DM, cardiac, renal - Uterine fundas large/ small for date - Decrease fetal movements - Fetal malpresentation - Viral infection in early pregnancy
10 Screening Procedures --- Cont. 3. Ultrasonography: - Screening tool in all trimesters - At weeks if fetal nuchal translucency - > 2.5 mm- chromosomal anomalies association - At weeks 75% fetal abnormalities can be diagnose
17 Screening Procedures ---Cont. 4. Maternal blood tests: - Maternal Serum alpha fetoproteins: . Produced by . Fetus &enter in maternal circulation. . Yolk sac in first trimester . Liver in second and third trimester . Normally increase from weeks . Abnormally raise on fetal capillaries exposure to amniotic fluid e.g. in NTD.
18 Maternal S. alpha fetoproteins --cont. - Raised level in neural tube defect(NTD). - Screen for NTD at weeks if +ve confirm with detailed USG. - Also raised in following conditions: . Miscalculated dates . Multiple pregnancies . Threatened abortion . IUD . Teratoma . Congenital nephrosis . Ant. Abdominal wall defects
21 Triple Test - Used for Down Synd. Screening. It comprises . AFP . hCG . uE3 (unconjugated oestriol )- Best carried at weeks. In DS AFP & uE3 are low while hCG is raised- Triple test+ maternal age diagnose 60% DS- In trisomy 18 all above components are low
22 Quadruple test Triple test+ Inhibin A estimation This test + maternal age detects 76% DS
23 Double TestLow pregnancy associated plasma proteins-A (PAPP-A) level and raised serum Beta-hCG during 1st trimesterDouble test+ maternal age diagnose 60% DS.
27 DIAGNOSTIC TESTS For high risk women on basis of screening tests An ideal test should be :- Least invasive- diagnose c. abnormality in early pregnancy.- Minimally interfering developing pregnancyDiagnostic tests are also not risk free.
28 Counselling Organize an appointment Couple should be present Explain: - Risk of occurance of c. abnormality- All tests available, their procedure, cost, diagnostic ability and benefits, possible risks- Possible management plainIf termination of pregnancy is unacceptable diagnostic tests would be fruitless.
29 NON INVASIVE TESTS Ultrasonography: Diagnostic USG is different from screening USG,- It takes longer time- Dx. Wide range of c. anomalies- Non invasive and diagnosis at spot possible- But possible only at large gestational ageColour doppler further enhance the capability especially for cardiac malformations and renal agenesis.
30 Other Soft Signs short ears cerebellar hypoplasia cholecystomegaly Mild cerebral ventriculomegalyHypoplasia of middle phalanx of 5th digitIncreased Iliac angleShort frontal lobe
31 What are the 2T soft signs? Increased nuchal thicknessshort femur or humerusPylectasisechogenic foci in heartEchogenic Bowelchoroid plexus cysts
32 INVASIVE TESTS AMNIOCENTESIS: Aspiration of amniotic fluid which contain fetal cellsFluid can be used for estimation of- bilirubin level (for fetal haemolytic disease).- AFP-Acetyl cholinesteraseCells used for karyotyping (Chromosomal dis.)Fetal cells-cultured for 3 weeks- karyotyping.New technique-PCR, FISH-give result in 48 h.Preferred time of test 16weeks of pregnancy.
33 AMNIOCENTESIS---Cont. Procedure:Preliminary USG to confirm-duration of gestation, -placental site,- adequacy of liqour ( ml)Sterilize the abdomen22 G spinal needle is used.About 20 cc amniotic fluid is withdrawn.Give Anti- D to all Rh-ve mothers.Ask rest for 30 min.& restrict movements for 48h
35 AMNIOCENTESIS---Cont. Limitations (difficulties)of procedure: if- Anteriorly placed placenta- Multiple pregnancy.- Maternal obesity- OligohydramniosRisks:- Pregnancy loss 1 % Bleeding , Infection,- Rupture of membrane - Preterm labour&IUD- Leaking of Amniotic fluid- Increase risk of RDS in newborn
36 CHORIONIC VILLUS SAMPLING Collection of fragments of placental tissue (chorionic villi)- cells are examined for Dx. of C.Anomalies.Cytotrophoblastic (rapidly dividing) cells are used for direct karyotyping- result available within h.Chorionic villi are best source of DNACVS can be performed at 10 weeks gestation.Indications:1-DNA analysis for SCD,thallasemias, CF. hemophillias2-Chromosomal abnormalities3-Inborn error of metabolism
37 CHORIONIC VILLUS SAMPLING Procedure:Trans-abdominal approach preferred –under USG guidance in supine positionTrans-cervical approach is easy.In lithotomy position, sterilize area & Aspiration catheter and biopsy forceps.Introduce through Cx. under USG into placental tissue avoiding membrane ruptureRisks: Pregnancy loss 2-6%Before 10 weeks- associated with limb deformities, micrognathia, microglassia
40 FETAL BLOOD SAMPLING (FBS) Fetal blood- lymphocyte are rapidly cultured, results within hours.Indications: 1- Prenatal Dx. DNA available for Cytogenetic studies In failed amniocentesis, and mosaicism in chorion or amniotic fluid.2-Fetal assessment: for red cell alloimmunization, (Hb;Hc,TrF) Hydrops fetalis, viral infection, platelets alloimmunizationUnfortunately Associated with highest rate of fetal loss.Currently used for blood transfusion in-utero in fetal A.
41 FETAL BLOOD SAMPLING (FBS) Procedure : (cordocentesis):The sites for FBS are placental insertion of umbilical cord, abdominal insertion of cord, intrahepatic fetal vein and fetal heart.Suitable time is weeksRisks:- Bleeding from site of puncture- Cord haematoma- Fetal bradycardia- Fetal death
42 EMBRYOSCOPY & FETOSCOPY Direct visualization of embryo and fetus.Limited field of vision.Provide information only about external fetal structures .
43 NEW MOLECULAR ANALYTIC TECHNIQUES Fetal cell obtained by CVS and Amniocentesis can be used for prenatal Dx. For congenital anomalies by following new techniques1- Southern blotting:Cleavage of chromosomal DNA at specificsites and used for tests2- PCR3- FISH
44 Polymerase chain reaction (PCR) Amplify specific DNA and RNA fragmentsOnce nucleotide sequence of a region of DNA strand is known, complimentary oligonucleotides & polymerase are added to single strand DNARepeat process 30 times to get adequate DNAPCR identify specific DNA sequence for gene mutation & prenatal Dx. at an earlier stage before an embryo transfer in IVF cycle.
45 FLOURESCENT IN SITU HYBRIDIZATION FISH allows detection & localization of specific DNA sequence in interphase or metaphase.Advantage – results available in h.Disadvantage – fail to detect big structural rearrangementsIdentify 80% clinically relevant abnormalities, helpful for early decision about further management of affected pregnancies.
46 MANAGEMENT OF FETAL C. ANOMALIES It is a tedious task, requires skillful, sympathetic & professional approach.Management options- Termination of pregnancy- In- utero management if possible- Conservative management
47 POSTPARTUM MANAGEMENT OF C.A. For better understanding of congenital anomaliesand its impact on future reproductive performance ofcouple, following procedures are carried out onaffected babies/ abortusses:Physical examination /postmortemFetal tissue(blood, skin, placenta) for karyotypingPlacenta and membrane for histopathologyPlacental & baby swab for microbiology & virology.Baby gram (x-rays of whole baby)Baby photograph
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