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 – 1/3rd 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time sonographic control, with the stilette in.The stilette is withdrawn and few drops of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
A)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.

11. 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

12. 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.

13. 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)

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

15. CHORIONIC VILLUS SAMPLING SUMMARY

16. 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
1st trimester-safe 2nd trimester -risky
Maternal effect following
termination of pregnancy
Very little More traumatic physically and
psychologically

17. 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.

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

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

24. 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.

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

28. THANK YOU