FETAL TISSUE SAMPLING FORDIAGNOSIS OF GENETIC DISORDERS

CHORIONIC VILLOUS SAMPLING“A PERSONAL APPROACH”

DR. RAJU SAHETYAM.D. ; D.G.O. ; D.F.P. ; F.C.P.S., F.I.C.O.G.

OBSTETRICIAN & GYNAECOLOGISTPUSHPA MATERNITY HOME

BOMBAY - INDIA

CHORIONIC VILLUS SAMPLING IN PRENATAL DIAGNOSIS

SAFETY & UTILIZATION DIFFICULTIES NCOUNTERED

DR. RAJU SAHETYAM.D. ; D.G.O. ; D.F.P. ; F.C.P.S., F.I.C.O.G.

OBSTETRICIAN & GYNAECOLOGISTPUSHPA MATERNITY HOME

BOMBAY - INDIA

Historical perspective in prenatal diagnosis

Modern era in 1952 by Bevus – technique of amniocentesis

Liley in 1961 – severity of erythroblastosis bilirubin level

IN 1966 – fetal cells from amniotic fluid cultured & karyotyped

In 1966 Hahnemann fetal chorionic villi T.V. by hysteroscope

Historical Perspective in prenatal diagnosis (cont)

In 1970, Chinese workers blind aspiration of chorionic villi for fetal sex

In 1982, Kazy et al., - role of ultrasonography in successful CVS

In 1985, Brambati et al., rapid uncultured villi – Trisomy 21 at 11 week

Milan group able to minimize maternal cell contamination

Diagnostic techniques for the 1st trimester

Pre-implantation embryo biopsy

Fetal cells isolated from maternal blood

Coelocentesis

Chorionic villous sampling

Ultrasonography

Diagnostic techniques in the 2nd trimester

Late chorionic villous sampling

Amniocentesis

Maternal biochemical analysis

Ultrasonography

Fetal blood sampling

IntroductionChorionic Villus Sampling

Well established in prenatal diagnosis

Villi have same genetic constitution

Reflects chromosomal , biochemical & DNA

CVS as alternative to amniocentesis

Safe, reliable, widespread application

Multicentric study – sampling success 98%

Indications for CVS in our multicentric study A. Increased risk for Chromosome anomalies 1.Advanced maternal age > 35 years 2.Previous aneuploid offspring 3.Parental balanced structural rearrangement a. Reciprocal translocation b. Robertsonian translocation c. Inversions 4.Maternal Abnormal serum screening 5.Ultrasound diagnosis of anomalies a. Major malformations b. Minor anomalies B. Previous offspring with NTDC. Parents carriers of Mendelian traits D. X-Linked Recessive Didorders

Utilization of CVSUtilization of CVS

Rapid Karyotyping – when fetal blood sampling unavailable

Excellent source of fetal DNA – for prenatal diagnosis

Cloning of genes & to develop DNA probesEnzyme expression – to identify inborn errors of

metabolism

PATIENT EVALUATION

GENETIC COUNSELLING

INDICATION FOR REFERAL REVIEWED

ALTERNATIVE PROCEDURES DISCUSSED

RISKS, COMPLICATIONS AND ADVANTAGES

TESTING VERSUS NO TESTING

INFORMED WRITTEN CONSENT

CLINICAL EVALUATION

OBSTETRIC HISTORY

GENITAL INFECTIONS

BLEEDING IN CURRENT PREGNANCY

PATIENT EVALUATION

ULTRASOUND EVALUATION

FETAL VIABILITY

GESTATIONAL AGE

CHORION FRONDOSUM

SUB-CHORIONIC BLEEDING

UTERO-CERVICAL RELATION

MULTIPLE GESTATION

PROCEDURE ORIENTATION

PROCEDURE RELATEDPROCEDURE RELATEDANATOMY & EMBRYOLOGYANATOMY & EMBRYOLOGY

GESTATION SAC DOES NOT FILL THE UTERUS

CHORIONIC MEMBRANE SURROUNDS AMNIOTIC CAVITY

EXTAEMBRYONIC COELOM CHORION LAEVE &

CHORION FRONDOSUM VILLI FLOAT AND LOOSELY

ANCHORED FRONDOSUM VILLI

MITOTICALLY ACTIVE

TECHNIQUES OF CHORIONIC VILLUS SAMPLING 9 TO 11 WKS

TRANSCERVICAL -CHORIONIC VILLUS SAMPLING T.C. - CVS 80 % IN OUR SERIES

TRANSABDOMINAL - CHORIONIC VILLUS SAMPLINGT.A. -

THE SELECTION OF THE ROUTE OF VCS AT THE DISCRETION OF THE OPERATOR AND DEPENDS ON :

LOCATION OF CHORION FRONDOSUM

POSITION OF UTERUS AND BLADDER

PRESENCE OF UTERINE OR CERVICAL ABNORMALITIES

PATIENTS CO-OPERATION

DEVICES USED IN C V S PERSONAL EXPERIENCE

T.C. - CVS STAINLESS STEEL RIGID / MALLEABLE

OLIVE TIP, GAUGE 16, LENGTH 20 TO 22 cms 10CC DISPOSABLE SYRINGE

T.A. - CVS LONG SPINAL NEEDLE,GAUGE 20/18,

LENGTH 10 TO 16 cms 10CC SYRINGE / MECHANICAL SUCTION

WITH COLLECTING BOTTLE

DEVICES USED IN CVS PERSONAL EXPERIENCE COMMON TO BOTHTRANSPORT CULTURE BOTTLE, PETRIDISH, LAB SUITABLE MEDIUM, VERTICAL TORCH /DISSECTING MICROSCOPE, PICK UP FORCE

CANNULAECONOMICAL, REUSABLE, EASY AUTOCLAVABLE, CLEANSED WITH SODIUM HYPO CHLORIDEMALLEABLE TO ALL SHAPES, OLIVE TIP ENABLES GOOD IMAGING

TECHNIQUE TRANSCERVICAL CHRONIC VILLUS SAMPLING

ULTRASOUND EVALUTION

ASEPTIC PRECAUTIONS

PREFORMED CANNULA

ULTRASOUND GUIDANCE

NEGATIVE SUCTION

“TO & FRO” MOVEMENTS

OBSTETRICAN-SONOLOGISTCO-ORDINATION

Technique – Transabdominal Chorionic Villus Sampling

Ultrasound evaluation Aseptic precautions Ultrasound guided free

hand technique “Back & Forth”

movements Lower fetal loss by 0.5% Reduced incidence of

immediate bleeding

CHORIONIC VILLUS SAMPLINGCHORIONIC VILLUS SAMPLINGIN TWIN PREGNANCYIN TWIN PREGNANCY

SPECIFIC COUNCELING SEPARATE SETS OF

DEVICES DIFFERENT ROUTES LIMIT ASPIRATION SITES DIANOSTIC ERRORS SELECTIVE TERMINATION VANISHING TWIN

ASSESMENT OF VILLI QUALITY

DISTINCTIVE FROND LIKE APPEARANCE

BUD-LIKE PROJECTIONS

BLOOD VESSELS COURSING ALONG THE SURFACE

QUANTITY - 15 TO 20 mgs. WET, WEIGHT

CVS - SAFETY

MATERNAL

REFERRAL INDICATION REVIEWED.

PATIENT EVALUATION

PREVIOUS PREGNANCY WASTAGE.

BLEEDING IN PRESENT PREGNANCY

INFECTIONS INVESTIGATE & TREAT

Rh SENSITIZATION--INCREASED RISK

RISE IN ALPHA-FETO PROTIENS

CVS - SAFETY

FETUS

• GESTATIONAL AGE CO- RELATION WITH USG.

• TO RULE OUT DISCREPANCY

• MULTIPLE GESTATION - RISKS INCREASES

• SERIAL SCANS--BEFORE & AFTER PROCEDURE

• MINIMISE VASCULAR INSULT

• FOLLOW UP MID-TRIMESTER SCAN & ALPHA-FETO PROTIENS

DIFFICULTIES ENCOUNTEREDDIFFICULTIES ENCOUNTEREDDUE TO CERVICAL FACTORSDUE TO CERVICAL FACTORSDECREASED CANNULA

MANEUVERABILITYLONG CX, PIN POINT STENOSED BLEEDING AND INFECTIONS

DIFFICULTIES ENCOUNTEREDDIFFICULTIES ENCOUNTEREDDUE TO UTERINE FACTORSDUE TO UTERINE FACTORS

POSITIONSDEVIATIONCONTRACTIONSSCARS & GROWTHS

DIFFICULTIES ENCOUNTERED DIFFICULTIES ENCOUNTERED DUE TO CHORIONIC DUE TO CHORIONIC

FRONDOSUMFRONDOSUMLOCATIONLOW LYINGTHICKNESSSUB CHORIONIC BLEEDING HEMATOMA

DIFFICULTIES ENCOUNTEREDDIFFICULTIES ENCOUNTEREDDUE TO MATERNAL BLADDERDUE TO MATERNAL BLADDER

FULL BLADDERACCESS TO CX, HIGH REACH

CHORION, MOBILITY OF UTERUS, DISCOMFORT.

INSUFFICIENT BLADDERPOOR IMAGING & GUIDANCE,

CERVICO-UTERINE ANGLE

DIFFICULTIES ENCOUNTEREDPERSONAL EXPERIENCE -10 YRS.IN T.A. - CVS

DISCOMFORT MYOMAS POSTERIOR LOCATION BOWELS INTERVENING MECHANICAL SUCTION OBESITY PREVIOUS SCARS

PREGNANCY OUTCOME IN 5200 CASES

NORMAL LIVE BIRTHS 4800

NEONATAL DEATHS 11

SPONTANEOUS ABORTIONS 63

PREMATURE DELIVERIES 22

STILL BIRTHS 13

IUFD 3

ABNORMAL KARYOTYPE 132

DEVELOPMENTAL DEFECTS 13

LOST TO FOLLOW UP 143

PREGNANCY OUTCOME IN 5200 CASES

DEVELOPMENTAL DEFECTS REPORTED

LIMB DEFECTS 3

ENENCEPHALY 2

OLIGOHYDRAMINIOS 6

HYDROCEPHALUS 2

RISK WITH CHORIONIC VILLUS SAMPLING

FETAL LOSS

INTRAUTERINE INFECTIONS

PERFORATION OF AMNIOTIC SAC

MID-TRIMESTER OLIGOHYDRAMNIOS

FETAL GROWTH AND DEVELOPMENT

MATERNAL CELL CONTAMINATION

RISK WITH CHORIONIC VILLUS SAMPLINGCVS & LIMB ABNORMALITY

CVS PRIOR TO 8.6 WEEKS GESTATION

VASCULAR INSULT

INCOMPLETE MORPHOGENESIS

DISRUPTS NORMAL EMBRYO

PATIENT’S ACCEPTANCE

SHORTER WAITING

PRIVACY

COMFORT

ADEQUATE COUNSELLING

WELL INFORMED PROCEDURE

CONCLUSION - I

CHORIONIC VILLUS SAMPLING HAVE PROVED TO BE REASONABLY SAFE AND RELIABLE TECHNIQUE WITH WIDESPREAD APPLICATIONS AND A HIGH DEGREEE OF ACCEPTANCE AMONG WOMEN UNDERGOING PROCEDURE

FETAL LOSS RISK HAS BEEN DEMONTRATED AS LOW ASAMNIOCENTESIS

NO ADVERSE EFFECTS WERE FOUND ON FETAL GROWTH AND DEVELOPMENET IF CVS PERFORMED BETWEEN 9 & 11 WEEKS GESTATIONS

CONCLUSION - II

SELECTION BETWEEN T.C.-CVS / T.A.-CVS IS AT THE THE DISCRETION OF THE OPERATOR AND DEPENDS ON

LOCATION OF CHORION, POSITION OF UTERUS, PATIENTS CO-OPERATION.

OBSTETRICIAN - SONOLOGIST CO-ORDINATION IS OF UTMOST IMPORTANCE FOR GOOD SAMPLING

WITH ADVANCES IN DAN TECHNOLOGY, ACURATE,SAME DAY RESULTS, FOR PRENATAL DIAGNOSISBY CVS WITHOUT THE NEED FOR CULTURE IS POSSIBLE