INVASIVE PROCEDURES
by
DR J JEEBODH
AIM OF PRESENTATION
• Briefly discuss options available for prenatal
diagnosis
• Briefly discuss therapeutic options
• Procedure/technique
• Complications
• Limitations
DIAGNOSTIC
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Amniocentesis
Chorionic villus sampling
Cordocentesis and other methods of FBS
Fetal tissue biopsies
Coelocentesis
Fetoscopy
AMNIOCENTESIS
Removal of fluid containing
fetal cells and biochemical
products from amniotic
cavity
Cells in amniotic fluid are
desquamated from fetal
skin & sloughed from
GIT,urogenital & resp
tract and amnion
INDICATIONS
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CHR and DNA analysis
Biochemistry
Fetal infection
Lung maturity
Chorioamnionitis
Obstetric cholestasis
Therapy
PROCEDURE
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Performed more than 15weeks & up to 18 weeks
Consent and counselling
Sonar
Transabdominal approach
Asepsis
Direct and continuous ultrasound guidance
22 gauge spinal needle
Avoid fetus , placenta and cord
EARLY AMNIOCENTESIS
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Less than 15 weeks
Only 10 to 12 ml
Success between 12 to 14 weeks ?95%
Fewer cells to culture
Advantages
Complications : More than post midtrimester
amnio, failure rate, fetal loss
COMPLICATIONS
• Fetal loss
• Pregnancy complications – abdo pain, amniotic
fluid leakage , vaginal bleeding
• Chronic leakage
• Orthopaedic abnormalities
• Fetal trauma
• Rhesus alloimmunisation
PREDISPOSING FACTORS TO SPONTANEOUS
ABORTIONS POST AMNIOCENTESIS
1. History of previous spontaneous or induced
abortion
2. Bleeding in current pregnancy
3. Age > 40 yrs
4. 3 or > 1st trimester abortions
5. 2nd trimester miscarriage or TOP
6. Obstetrician/operator experience
AMNIOCENTESIS & TWINS
• Single needle technique better than double
• Needle into proximal sac – aspirate
• Advanced into 2nd sac through membrane under
direct vision
• Concerns
• DO NOT USE DYES
• Fetal loss risk
CVS AND PLACENTAL BIOPSY
• Chorion frondosum or placental tissue sampled
• Alternative to amniotic fluid and FBS for prenatal
diagnosis of genetic disorders
• Villi excellent source of DNA
• Tissue obtained consists of syncytiotrophoblast
(outer non-dividing cells) and cytotrophoblast
(rapidly dividing cells)
Cytogenetic results in 48hours & final culture in 7d
INDICATIONS FOR CVS
• Maternal age at 35 yrs or more at
conception
• Previous child with aneuploidy
• Parent who is a carrier of a balanced
translocation or other CHR abnormalities
• Autosomal recessive disease
• Women who are carriers of sex – linked
disease
PROCEDURE
• Between 11 to 14 weeks
• Transabdominal or transcervical (less frequently)
• Needle into placenta under continuous
simultaneous ultrasound guidance
• Placental biopsies done in 2nd and 3rd trimesters
COMPLICATIONS
• PROCEDURE RELATED
Miscarriage
Limb reduction
Risk of late termination
• DIAGNOSIS RELATED
More cytogenetic ambiguous results
Mosaicism & other variants(1%) – false negative
results
CVS AND LIMB DEFICIENCES
• Risk and severity of limb deficiency appear to be
associated with timing of CVS
• Overall risk for transverse limb deficiences 0.03% - 0.1%
(1 in 3000 to 1 in 1000)
• Less than 10 weeks : 0.2% & more proximal limb
deficiences and orofacial defects
• At or greater than 10 weeks : 0.07% & most limited to
digits
• Possible mechanism some form of vascular disruption
CVS AND TWINS
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Loss rate similar to amnio
Concerns
Techniques to reduce contamination
Advantages
Disadvantages
FETAL BLOOD SAMPLING
DIAGNOSTIC
CHR abnormalities
DNA abnormalities / single gene defects
Fetal anaemia
Fetal thrombocytopaenia
Fetal hypoxia / acidosis
Fetal infection
THERAPEUTIC
Anaemia , thrombocytopaenia , drug administration ,
fetacide
PROCEDURE OPTIONS
SAMLING SITE
1. Fetal heart
2. Fetal intrahepatic
vessels
3. Umbilical cord
(cordocentesis)
-Easiest site to
puncture is 1cm from cord
insertion into placenta
(avoid free loop)
-More than 20 weeks :
5ml
-Less than 20 weeks :
caution with volume
removed
COMPLICATIONS
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FETAL
bleeding or haematoma
fetal bradycardia
Chorioamnionitis
Placental abruption
Amniotic fluid leakage or ROM
Death
Disability in survivors
Transmission of maternal infection
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MATERNAL
Alloimmunisation
Chorioamnionitis
Maternal trauma
Possibilty of emergency delivery
Post procedure pregnancy loss rate :1%
• Tranfusion carries higher procedure related risk than blood
sampling
• Operator skill important
COELOCENTESIS
• Earlier than CVS
• Coelomic space between amniotic membrane and
uterine cavity
• Under re-evaluation
• 1 to 2.5ml of amniotic fluid (vol by 9 weeks ±5 to
6ml)
• Cells mostly haemopoetic in origin
• 90% of cells viable before 7 weeks
• 95% success at 7 weeks
FETAL TISSUE BIOPSIES
• Need for diagnosis of disorders not amenable to
molecular approaches
• Indications are possible or potentially lethal or
severely handicapping conditions in fetus affecting
skin, liver, muscle & occasionally for diagnosis of
fetal tumours
• Options : fetoscopic directed biopsies ,ultrasound
guided aspiration or ‘tru-cut’ technique
FETAL SKIN BIOPSIES
• Only a few major dermatological disorders associated with
CHR abnormalities or enzyme defects detectable on either
amniotic fluid or chorionic villi
• Ultrasound visualisation useless in majority of serious
cutaneous abnormalities
• Actual visualisation of skin and histology only way to
make diagnosis
• Obtained under direct visualisation using fetoscopy or
ultrasound guidance
• Heal with no scar formation
• Complications : ROM ,bleeding , infection , miscarriage
FETAL LIVER BIOPSIES
• Successfully used for prenatal diagnosis of :
- ornithine transcarbamylase deficiency
- carbamyl phosphate synthetase deficiency
- Von Gierke’s disease
- Primary hyperoxaluria type 1
• Needle or coring biopsy instrument inserted into
RUQ of fetal abdomen
FETAL MUSCLE BIOPSIES
• Majority of DMD currently diagnosed by
molecular analysis of the gene using CVS
• Either through detection of deletion mutation or
by linkage analysis
• Is possible that deletion mutation not found
• Muscle biopsy allows finding of dystrophin
• Complications : nerve damage & bleeding
• ONLY USE IF INDICATED
• EXPERIENCED OPERATOR
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Other organs : lung , kidney
Tumours
Most indications DO NOT outweigh risk
Risk of pregnancy wastage relatively high
Biopsy when yield exceeds risk
Complex analysis of specimens
THERAPEUTIC INVASIVE PROCEDURES
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Rhesus isoimmunisation
Platelet disorders
Drugs
Multiple pregnancy reduction and selective termination
Fetal shunts
Relief of polyhydramnios
Therapeutic amnioinfusion
Open fetal surgery
TTTS
Fetoscopy
MULTIFETAL PREGNANCY REDUCTION AND
SELECTIVE TERMINATION
• Obstetric outcome of triplets & higher numbers of
fetuses significantly compromised
• First trimester procedures for fetal number:
MFPR
• 2ND Trimester procedures for fetal abnormalities :
selective termination
MFPR
• Transvaginal aspiration or transabdominal KCL
• Embryo selection
- exclude abnormalities or aneuploidy
- choice based on ease of approach
- avoid embryo closest to cervix
• Timing – 9 to 12 weeks
SELECTIVE TERMINATION OF ABNORMAL
TWIN
• Case selection critical
• If placenta shared ,demise of one twin potentially
places surviving co–twin at increased risk
• KCL only in dichorionic twins
• Umbilical cord ligation or occlusion in
monochrionic twins
• Risk of fetal loss
TTTS MANAGEMENT
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Expectant
Medical no benefit
Serial amniodrainage
Septostomy with /without amniodrainge
Selective fetocide – ligation of umbilical cord/
cord coagulation, cord embolisation
• Laser occlusion – fetoscopic directed laser
ablation of vascular anastomoses
FETOSCOPIC LASER ABLATION
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Cause-orientated approach
Fetal complications
Maternal complications
Fetal survival
Risk of neurological sequelae
FETAL SHUNTS
• Can perform antenatal drainage of pathological
collections of fluids in fetus
• Direct needling or shunting
• In theory, drainage of abnormal fluid collections
possible from fetal abdo,brain,chest,renal tract
• Pleural effusions – pleuroamniotic shunt
• Vesicoamniotic shunts in obstructive uropathy or
to decompress a dilated urinary tract
BLOOD TRANSFUSIONS
• Intraperitoneal(less preferred) or intravascular
• INTRAPERITONEAL
- blood absorbed via lymph vessels
- 10% of cells absorbed each day by non-hydropic
fetus
- absorption in hydropic fetus poor
- disadvantages : slow correction of HB,increased
risk of trauma, can obstruct cardiac return, lower
survival rates than intravascular
BLOOD TRANSFUSIONS CONTINUED
• INTRAVASCULAR
- Umbilical vein
- 22 gauge needle
- at insertion or free loop
volume determined by Hct and gest age
When to transfuse? Hct < 30 % ( <25th percentile
for GA) OR
Vol = (weeks in gestation – 20) x 10ml
THERAPEUTIC AMNIOCENTESIS
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Transabdominal
Decrease amniotic fluid under sonar guidance
Prolong gestation & improve survival
Aim : DVP <8cm or AFI normal range
Complication rate 1.5% - PROM,
chorioamnionitis, abruptio, membranous
detachment
• Maximum 3litres
• TNT patch
AMNIOINFUSION
• INDICATION : Improve visualisation of
fetal anatomy or severe oligohydramnios /
anhydramnios
• FLUIDS: physiological solution- N/S,
RL,5% gluc
• VOL: Minimum needed to improve
visualisation
• COMPLICATIONS
CONCLUSION
• Risk of HIV transmission
• Counseling – Procedure related risks,
complications, limitations
• Individually tailored risk assessment before
procedure
THANK YOU