Amniocentesis ,CVS and karyotyping

indcation,how and when to perform amniocentesis,chorionic villus smpling and karyotyping has been explained

1. AMNIOCENTESIS DR POOJA PANDEY PGJR 1st yr

2. AMNIOCENTESIS- IT IS THE DELIBERATE PUNCTURE OF AMNIOTIC FLUID SAC PER ABDOMEN. Usually done at 14-16week of pregnancy

3. PROCEDURE- 1.After emptying the bladder , the patient remains in dorsal position. 2.The abdominal wall is prepared aseptically and draped. 3.The proposed site of puncture is infiltrated with 2ml of 1% lignocaine. The preferred sites for blind procedures are – a)In early months – 1/3 rd of the way up the uterus from symphysis pubis. b)In later months- transisthmic suprapubic approach after lifting the presenting part or through the flanks in between the fetal limbs or below the umbilicus behind the neck of the fetus. A 18-20 gauge spinal needle about 4”in length is pierced into the amniotic cavity under real time sonographic control, with the stilette in.The stilette is withdrawn and few drops of liquor are discarded . About 30ml of fluid is collected in a test tube for diagnostic purposes.

4. PROCEDURE OF AMNIOCENTESIS

5. INDICATIONS DIAGNOSTIC INDICATIONS A)EARLY MONTHS(14-16 weeks) I)Antenatal diagnosis of chromosomal and genetic disorders - i)sex linked disorders ii)karyotyping iii)inborn error of metabolism iv)neural tube defects B)LATE MONTHS- i)Fetal maturity ii)Meconium staining of liquor iii)Degree of fetal haemolysis in Rh sensitized mother iv)Amniography or fetography THERAPEUTIC INDICAIONS i)Induction of abortion by instillation of chemicals such as hypertonic saline , urea and prostaglandins ii)Repeated decompression of the uterus in acute hydraminos. iii) Amnioinfusion done in case of oligohydraminos , to prevent lung hypoplasia, to dilute meconium stained amniotic fluid , to minimize umbilical cord compression during labor.

6. COMPLICATIONS MATERNAL- i)Infection ii) Haemorrhage - placental or uterine injury iii)PROM (premature rupture of membrane) and Pre term labour iv)Maternal isoimmunisation in Rh- ve cases. B)FETAL- i) Abortion ii)Trauma iii) Feto -maternal haemorrhage iv)Oligohydraminos

7. AMNIOCENTESIS SUMMARY

8. CHORIONIC VILLUS SAMPLING

9. CHORIONIC VILLI Chorionic villi are villi that sprout from the chorion in order to give a maximum area of contact with the maternal blood. CHORIONIC VILLI SAMPLING- Is preformed for prenatal diagnosis of genetic disorders. A few villi are collected from the chorionic frondosum under ultrasound guidance with the help of long malleable polyethylene catheter introduced transcervically along the extrovular space.

10. PROCEDURE- I)TRANSCERVICAL II)TRANSABDOMINAL TRANSCERVICAL It is performed by inserting a thin plastic tube through vagina &cervix to reach placenta with the help of ultrasound guided images. 10-12weeks

11. TRANSABDOMINAL It is performed by inserting a needle through the abdomen uterus to reach placenta with the help of ultrasound guided images. 10weeks to term.

12. INDICATIONS Family history of a chromosomal abnormality or other genetic disorder. Parents are known for a genetic disorder. Abnormal first trimester screen results. Increased nuchal translucency or other abnormal ultrasound findings. Advanced maternal age (>35yrs)

13. COMPLICATIONS Miscarriage Infections Bleeding Cramping and pain at puncture point Rupture of membrane Limb reduction defects when performed <3weeks

14. CHORIONIC VILLUS SAMPLING SUMMARY

15. COMPARISON BETWEEN CHORIONIC VILLUS SAMPLING AND AMNIOCENTESIS Chorionic villus sampling Amniocentesis CHORIONIC VILLUS SAMPLING AMNIOCENTESIS TIME 10-12 week 14-16week Material for study Trophoblast cell Fetal fibroblast Karyotype result Direct preparation- 24-48hrs Culture-10-14days Culture-3-4 weeks Fetal loss 1-2% 0.5-1% Accuracy accurate Highly accurate Termination of pregnancy when indicated 1 st trimester-safe 2 nd trimester -risky Maternal effect following termination of pregnancy Very little More traumatic physically and psychologically

16. KARYOTYPING Karyotype is an organized profile of an individual’s chromosomes. Karyotyping is a technique that is use to examine chromosomes in a sample of cells which can help identify genetic problems as the cause of disorder or a disease.

17. PURPOSE OF KARYOTYPING TO LOCATE OR VISUALISE THE CHANGES IN THE NUMBER OF CHROMOSOMES AND ABNORMALITY IN THE STRUCTURE. TO LOCATE THE EVOLUTION

18. BASIS OF KARYOTYPING BASED ON THREE PATTERNS ON SIZE OF CHROMATIDS. ON THE BASIS OF BANDING PATTERNS. BASIS OF CENTROMERIC POSITIONS.

19. ADVANTAGE OF KARYOTYPING HELPS IN STUDYING CHROMOSOME BANDING PATTERN. HELPS IN IDENTIFICATION OF CHROMOSOMAL ABERRATIONS. DIAGNOSIS OF PRENATAL GENETIC DEFECTS. STUDYING EVOLUTIONARY CHANGES. REVEALS STRUCTURAL FEATURES OF EACH CHROMOSOMES .

20. ABNORMAL RESULTS MAY BE DUE TO A GENETIC SYNDROME OR CONDITIONS SUCH AS DOWN SYNDROME KLINEFELTER SUNDROME PHILADELPHIA CHROMOSOME TURNER SYNDROME TRISOMY 18

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