Author: Ms Christa Maria Joel Moderator- Dr. Padma Department of Obstetrics and Gynecology Father Muller Medical College 4th Year MBBS

1. Christa Maria Joel

2. • The process of identifying malformations, disruptions, chromosomal
abnormalities and other genetic syndromes in developing foetus.
• Purpose: It is not simply to detect abnormalities in foetal life and allow
termination.
Definition

3. • Provide a range of choice to the couples at risk of having a child with
abnormality.
• Provide reassurance and reduce anxiety.
• Allow couples at high risk to know that the presence or absence of disorder could
be confirmed by testing.
• Allow the couples the option of appropriate management- psychological,
pregnancy/ delivery, postnatal.
• To enable prenatal treatment of affected foetus.
Purpose of prenatal diagnosis

4. Maternal risk factors Prenatal risk factor
Maternal age > 35 years. Oligohydramnios
Family history of neural tube defects Polyhydramnios
Previous baby born with neural tube defect Severe symmetrical foetal growth restriction
Previous child with chromosomal anomaly Abnormal ultrasound findings
One or both parents- carriers of sex linked or
autosomal traits
Uncontrolled diabetes mellitus in the peri
conceptional period
One parent is known to carry a balanced
translocation
Contact with infection or intake of teratogenic
drugs
History of recurrent miscarriage Presence of soft tissue markers of
anomaly on USG and
Abnormal maternal serum screening.
Risk factors for prenatal diagnosis

5. Procedures
Screening tests:
1st trimester – NT
scan, nasal bone,
PAPP-A , hcG
2nd trimester –
MSAFP
, Triple test
and Quadruple test
Invasive tests:
Chorionic villus
sampling,
Amniocentesis,
cordocentesis or
Percutaneous
umbilical blood
sampling.
Non invasive methods:
Cff-DNA from maternal
plasma, fetal cell isolation
from maternal blood, USG,
MRI, Peri implantation
Genetic Diagnosis,
Fetoscopy.

6. • Maternal serum alpha fetoprotein:
- Oncofoetal protein produced by yolk sac
and foetal liver.
- Highest level in foetal serum and
fluid reached around 13 weeks and
thereafter decreases.
- Maternal serum level reaches a peak
around 32 weeks.
Biochemical markers

7. • Trisomy – Down’s syndrome
• Gestational trophoblastic disease.
Low levels in:
• wrong gestational age
• open neural tube defects
• multiple pregnancies and Rh
isoimmunisation
• IUFD: intra uterine foetal death
• anterior abdominal wall defects and
renal anomalies.
Elevated in a number of conditions:

8. • Free beta hcG :
- Glycoprotein with molecular weight of 36,000 to 40,000D.
- Chemically and functionally similar to pituitary luteinizing hormone.
- Placental GnRH control hCG formation.
- Produced by syncytiotrophoblast of placenta and is secreted into the blood of mother
and fetus.
- Functions:
- Rescue and maintenance of corpus luteum till 6 weeks of pregnancy.
- Hcg stimulates Leydig cells of male foetus to produce testosterone.
- Immunosuppressive activity.
- Stimulates both adrenal and placental steroidogenesis.
- Stimulates maternal thyroid
- Promotes secretion of relaxin from corpus luteum.

9. - In early pregnancy, doubling time of
hcG is 1.4 -2 days, reaches maximum
value between 60-70 days and
decreases by 100-130 days and
remains at that level with a slight
peak at 32 weeks.
- High hcG-trisomy 21, hydatidiform
mole, multiple pregnancy
- Low hcG- ectopic pregnancy and
spontaneous abortion.

10. - Inhibin A :
- Dimeric glycoprotein
- Produced by corpus luteum and placenta.
- Raised in Down’s syndrome.
• Unconjugated estriol(uE3 ):
- Estriol is a steroidal hormone produced by syncytiotrophoblast.
- First detectable at 9 weeks (0.05ng/ml), increases to 30ng/ml at term.
- Low estriol – Down’s syndrome, anencephaly, adrenal atrophy, hydatidiform mole, fetal
death.
• Pregnancy associated plasma protein-A (PAPP-A):
- Secreted by syncytiotrophoblast
- Act as an immunosuppressant in pregnancy

11. • Screening parameters:
- Biophysical methods – USG measurement of NT and nasal bone
- Biochemical methods – free beta hcG and PAPP-A.
• Time of test: 11 to 14 weeks
• Trisomy 21 – PAPP-A reduced, hcG increased, NT increased
Screening Methods: First trimester screening

12. • Nuchal transluency (NT): fluid filled
space between fetal skin and underlying
soft tissue at region of the fetal neck.
- NT>3mm – abnormal
- Combined tests detect trisomy 21 in
92% cases with a false positive rate of
5%
• Advantages: once a woman is screen
positive, diagnostic tests should be
done early.
• Targeted ultrasound during the second
trimester and fetal echocardiography
done when NT is >3 mm.

13. • MSAFP Testing:
- 15 to 22 weeks
- Measured in ng/ml and expressed as 2.5
multiples of median when adjusted with
maternal weight and ethnicity is taken as cut
off point.
- Elevated MSAFP detects 85% of all neural
tube defects.
- Cases with such high values considered for
high resolution ultrasound imaging and/or
amniocentesis.
- Very low MSAFP- associated with increased
rates of miscarriages, stillbirth, neonatal
death.
Second trimester screening

14. • Triple test: MSAFP+hcG+uE3.
- Maternal age in relation to confirmed gestation age taken into account.
- Detection of down syndrome: MSAFP and uE3 reduced and hcG is high.
- 15-22 weeks.
- For confirmation: CVS/ amniocentesis done.
- Considered to be screen positive if risk ratio is 1:250 or greater.
3)Quadruple test : MSAFP+hcG+uE3+dimeric inhibin A
- In Down syndrome : MSAFP and uE3 are reduced and hcG and dimeric inhibin A are
high.
- Can detect trisomy 21 in 85% cases with a false positive rate of 0.9%
- Adjustments made for maternal age, weight and ethnic group.
• Best screening procedure is combined first and second trimester procedures.

15. Beta hcG
+PAPP-A
+NT
MSAFP Triple test Quadruple
test
Soft tissue
marker (NT &
NB)
Time (weeks) 11-14 15-20 15-18 15-20 11-14
Observation Beta hcG
increased
PAPP-A
decreased.
Increased positive positive NT >3 mm
Nasal bone
absent
Anomaly to
detect
Down’s
syndrome
Open neural
tube defects
Down’s
syndrome
Down’s
syndrome
Down’s
syndrome,
turner’s
syndrome
Detection
rate
85- 92% 85% 73% 85-92% 85-92%
False positive
rate
5% 3-5% 5% 0.9% 3-5%
Prenatal diagnosis: biochemical and biophysical
screening tests

16. Few villi collected from chorion frondosum under ultrasonic
guidance with the help of a long malleable polyethylene
catheter with a metal obturator along extra ovular space.
Obturator is then withdrawn. About 15-25 mg of
villi are aspirated in a 20 ml syringe creating a
negative pressure
Tissues obtained in a
tissue culture media
within the syringe
Invasive procedures
Chorionic villus sampling (CVS)- transcervical

17. Transabdominally:
• Done using a spinal needle 18-20
gauge under ultrasound guidance.
• Provides earlier diagnosis than
amniotic fluid studies.
Complications:
• Fetal loss (1 to 2%)
• Oromandibular limb deformities
• Vaginal bleeding
• False positive results – Placental
mosaics and maternal cell
contamination.
• In such situations amniocentesis
done to confirm diagnosis.

18. Contraindications (TC-CVS) :
• Cervical myoma
• Acutely angulated uterus, uterine malformations
• Infections- genital herpes and cervicitis
• Vaginal bleeding
CVS performed between 10 weeks and 13 weeks of gestation is safe and accurate
as that of amniocentesis.
Anti D immunoglobulin 50 microgram IM should be administered following the
procedure to a Rh negative woman.

19. • Aspiration of 20 ml of amniotic fluid through abdominal wall under ultrasound
guidance around 16 weeks of gestation
Amniocentesis

20. Indications : diagnostic-
Early months (15-20w)- genetic amniocentesis for antenatal diagnosis of
and genetic disorders :
• sex linked disorders
• Karyotyping
• Inborn errors of metabolism
• Neural tube defects
Later months -
• fetal maturity
• Degree of fetal hemolysis in Rh-sensitized mother
• Meconium staining of liquor

21. Therapeutic indications:
• First half:
- Induction of abortion by instillation of chemicals.
- Repeated decompression of the uterus in acute hydramnios.
• Second half:
- Decompression of uterus in unresponsive cases of chronic hydramnios.
- To give intrauterine foetal transfusion in severe hemolysis following Rh
isoimmunization.
- Amnioinfusion- infusion of warm normal saline into amniotic cavity to increase
the volume of amniotic fluid.

22. Empty bladder.
Abdominal wall is prepared
aseptically and draped.
Infiltrated with 2ml 1%
lignocaine.
20 or 22 gauge spinal
needle with stylet in about
4’’ in length is inserted to
amniotic cavity under real
time sonographic control.
Stylet withdrawn and few
drops of liquor is discarded.
Initial 1 to 2ml of fluid –
AFP or discarded if
contaminated with maternal
cells
Fetal karyotyping
30ml collected in test tube
for diagnostic purposes.
Fetal cardiac motion is to
be seen after the procedure.
Procedure
Patient is asked to report in case of uterine cramps, vaginal bleeding, leakage of liquor.

23. Precautions:
• Prior sonographic localization of placenta to prevent bloody tap and
bleeding.
• Prophylactic administration of 100mg of anti-D immunoglobulin in Rh negative
non immunized mother.
• Continuous visualization under USG reduces risk of injury, bloody or dry tap and
need for multiple insertion.
• Avoided in HIV positive women.
Hazards:
• Maternal : infection, hemorrhage, Premature rupture of membranes, premature
labor, maternal isoimmunization
• Fetal : fetal loss, trauma, fetomaternal hemorrhage, oligohydramnios.

24. Local anesthesia
A 22-gauge spinal
needle,13cm is inserted
through maternal
abdominal and uterine
walls under real time
ultrasound guidance
using a curvilinear probe.
Needle tip is progressed
carefully and it punctures
the umbilical vein 1-2cm
from the placental
insertion.
0.5 – 2 ml blood is
collected.
Cordocentesis/ PUBS- Done after 18 weeks

25. Precaution - anti D immunoglobulin
100microgram IM should be given to
Rh negative woman.
Risks:
• Abortion, preterm labor, IUFD
• Bleeding ,cord hematoma formation,
infection, fetomaternal hemorrhage,
preterm rupture of membranes

26. • Hematological – for foetal anemia, bleeding disorders, Rh disease,
hemoglobinopathies.
• Foetal infections – toxoplasmosis and viral infections
• Foetal blood gas and acid base status – in foetal growth restriction
• Foetal therapy – blood transfusion and drug therapy.
Additional tests

27. CVS Amniocentesis Cordocentesis
Time Transcervical 10-13
weeks
Transabdominal 10
weeks to term
After 15 weeks 18-20 weeks
Materials for study Trophoblast cells Foetal fibroblasts
Fluid for biochemical
study
Foetal WBC
Karyotype result Direct preparation-
24-48 hrs
Culture- 10-14 days
Culture- 3-4 weeks Culture- 24-48 hours
Foetal loss 0.5-1% 0.5% 1-2%
Termination of
pregnancy when
indicated
First trimester- safe Second trimester-
risky
Second trimester-
risky
Prenatal diagnosis- CVS, amniocentesis and
cordocentesis

28. • Foetal DNA comes in the maternal circulation from the placenta
• Cell free fetal DNA (cff-DNA) –detected in plasma and whole blood from 1st
trimester and gets rapidly cleared after delivery.
• Done from 10 weeks
• Cff-DNA increases with gestational age.
• Used to determine:
- Fetal blood group status
- Single gene disorders (Marfan’s Syndrome and Cystic Fibrosis)
- Fetal aneuploidy- trisomy 21
Non invasive methods- Detection of foetal DNA

29. • Foetal trophoblasts, lymphocytes, granulocytes, nucleated RBCs can be isolated
from maternal blood.
• Analyzed by FISH (fluorescence in situ hybridization)- diagnoses foetal
aneuploidy.
• But these are rare in maternal blood.
Intact foetal cells

30. • Ultra sonographic examination –can detect fetal anomalies-10 to 14 weeks
• Crown rump length(CRL) – if smaller than gestational age – chromosomal anomalies.
• Increased nuchal transluency-10 to 14 weeks –chromosomal abnormalities.
• Absence of nasal bone on USG -10 to 12 weeks- Down’s syndrome.
• Absence of calvarium(cranial vault) – anencephaly
• HC/BPD enlarged – hydrocephaly
• Width of lateral ventricle >10mm- ventriculomegaly.
• Also used in diagnosis of abdominal wall defects(omphalocoele ,gastrochisis),renal
anomalies
Ultrasonography

32. • Useful to obtain high soft tissue contrast and acquisition of images in axial, sagittal
and coronal planes.
• Gadolinium contrast MRI- not used in first trimester as it crosses the placenta.
• Indications
- Foetal: foetal anatomy survey, foetal biometry, foetal weight estimation, evaluation of
complex abnormalities.
- Maternal: cerebral vascular flow study for eclampsia and detection of thrombosis,
angiography, evaluation of maternal tumours, evaluation of placenta previa accrete
• Better compared to USG- detect depth of trophoblast penetration within the uterus/
bladder in cases with placenta previa accrete.
MRI

33. • Sagittal view
• Craniocaudal inverted image at 24
weeks of gestation
• U- uterine myometrium
• P- placenta
• Arrows- umbilical cord
• AF- amniotic fluid

34. • Done by:
- Polar body biopsy
- Blastomere biopsy from 6-8 cell embryo
- Trophectoderm biopsy (5-6 days blastocyst)
• Accuracy is high both for cytogenetic and single gene disorders.
• May be preferred to usual prenatal diagnosis where pregnancy termination is not accepted.
• Polar body biopsy: by removing the 1st or 2nd polar body in the preconceptional phase.
• Blastomere biopsy: one or two cells are aspirated through a hole made in the zona
pellucida by mechanical, laser or chemical means. Does not affect normal embryonic
development.
Peri implantation genetic diagnosis

35. • Intrauterine foetal transfusion: foetal anaemia
• Maternal oral therapy with propylthiouracil: foetal hyperthyroidism
• Digoxin or flecainide: foetal tachyarrhythmias
• Oral dexamethasone: congenital adrenal hyperplasia of a female foetus
• Foetal stem cell transplantation and foetal gene therapy- used in many
haematological, metabolic, immunological and inherited diseases.
• Intrauterine surgeries- laser therapy for TTTS, cystoscopic laser for posterior urethral
valves, foetal tracheal occlusion for congenital diaphragmatic hernia and release of
amniotic bands.
Foetal therapy