1. Confidence of Being Sure:
Case Studies in the diagnosis of Fetal
Chromosomal Abnormalities
DR. AMALA NAZARETH
MD. DGO. MBBS
SPECIALIST OB/GYN
PRIME HEALTHCARE GROUP

2. Prenatal Testing
 PRENATAL TESTING WIDELY USED AND RECOMMENDED TO
SCREEN CHROMOSOMAL ABNORMALITIES IN DEVELOPING
FETUS
 DOWN’S SYNDROME (TRISOMY 21), EDWARDS SYNDROME
(TRISOMY 18) AND PATAU’S SYNDROME (TRISOMY 13) CAN BE
DETECTED BY PRENATAL EVALUATION.

3. Prevalence of Disorders
DISORDER PREVALENCE COMPATIBILITY WITH LIFE
DOWN’S SYNDROME 1 IN 629 BIRTHS • INTELECTUAL AND
TRISOMY 21 1 IN 1340 (AT 25YRS) LEARNING DISABILITY
1 IN 353 (AT 35YRS) • CHARACTERISTIC
1 IN 35 (AT 45 YRS) FEATURES
• CARDIAC AND
INTESTINAL
DEFORMITIES
• INCREASED INFECTION
RISK
EDWARD’S SYNDROME 1 IN 5500 BIRTHS • HALF DIE WITHIN 1ST
TRISOMY 18 INCREASES WITH YEAR OF LIFE
INCREASED MATERNAL AGE • SEVERE INTELLECTUAL
DISABILITY
PATAU’S SYNDROME INCREASES WITH HIGHER 80% DIE WITHIN THE 1ST
TRISOMY 13 MATERNAL AGE MONTH
SURVIVORS HAVE FAILURE
TO THRIVE

4. Routine Prenatal Diagnosis
Invasive Non Invasive
 CHORION VILLUS SAMPLING  TRIPLE MARKER TESTS
 ULTRASOUND ( DOUBLE
 AMNIOCENTESIS MARKERS)
 CELL FREE FETAL DNA IN
THE MATERNAL BLOOD

5. Non-invasive Prenatal Diagnosis from Maternal blood
Current evidence suggests that non-invasive prenatal
testing from maternal blood ….
– Is a major step forward to improve the identification
of pregnancies at a high risk for trisomy 21, 18 and 13
– Has the potential to significantly reduce the number
of invasive procedures
– Is not considered as diagnostic for the time being

6. Common Misconceptions about NIPD
Non-invasive prenatal diagnosis does replace
– invasive testing
– first trimester risk screening
– ultrasound screening
Caveats
– rare complexities (e.g. confined placental mosaicism)
– performance in low risk situations

7. Suggested Algorithm
Serum Screening and/or And/ Sequencing of the Cell-free
Ultrasound examination Or DNA
Trisomy 21, 18 and 13
Invasive Cytogenetic
Diagnosis
Genetic Counseling
• Continue Pregnancy
Terminate Pregnancy
• Prepare for affected infant

8. TRIGENE – Non invasive Prenatal Diagnosis
• More than 70 thousand cases
• 100% detection rate
• 0.1% false-positive rate
• No false-negative case were reported

9. Clinical Cases 1
T21 case missed by biochemical screening
Age ： 31
Screening test ： 1/510 （ Low risk ）
Noninvasive Test ： T21
Karyotyping ： 47 ， XX ， +21

10. Clinical Cases 2
T13
Age: 32
Screening test: Low risk
Noninvasive Test ： T13
Karyotyping ： 47 ， XX ， +13

11. Clinical Cases 3
T13
Age: 32
Screening test: Low risk
Noninvasive Test ： T18
Karyotyping ： 47 ， XX ， +18

12. Clinical Cases 4
T13
Age: 34
Screening test: High risk
Noninvasive Test ： T18
Karyotyping ： 47 ， XX ， +18

13. Advantage of Non-invasive Pre natal diagnosis
• Non- invasive- Only 5ml of maternal peripheral blood is required
• No Risk - Absolutely safe without any risk of miscarriage
• Early Diagnosis - Can be done at the early stage of pregnancy, ~
12 weeks of pregnancy
• Highly accurate - close to diagnostic test, 100% sensitivity and
99.9% specificity

14. Thank you