1. Prenatal diagnosis Dr Hiba Ahmed Suhail M. B. Ch. B. /F. I. B. O. G
Prenatal diagnosis Dr Hiba Ahmed Suhail M.B. Ch. B./F.I.B.O.G. College of medicine University of Mosul

2. Prenatal diagnosis: Prenatal diagnosis is the identification of a disease prior to birth.
The early prenatal diagnosis and detection of congenital abnormality allows both parent and medical cares to plan the management for the pregnancy as:
Reassurance of the parent
Termination of pregnancy when the anomaly is incompatible with life .
The time ,mode and place of delivery prepared to ensure good prognosis of the neonate .
Offer in utero treatment.

3. Congenital anomaly refer to fetal alformation or disorders conferred by birth (born with )
Incidence 2-3 per 100 pregnancies
The prenatal detection of the congenital abnormality is one of the aims of the routine antenatal care

4. Classification of common congenital abnormalities
Structural abnormalities
congenital heart disease
Neural tube defects
Cleft lipand palate
Clubbed foot
Chromosomal abnormalities
trisomy 21(Downs syndrome) ,trisomy 13 and 18
Monosomy X(Turners syndrone )
Genetic
Cystic fibrosis
Sickle cell anaemia
Thalassemia
Miscellaneous
viral infection

5. Test for fetal anomaly
Screening is performed in all women in order to identify women who are at high risk of a disorder.
They do not confer any risk to the pregnancy and are performed for disorders which there are accurate prenatal diagnostic tests.
Diagnostic tests are carried out on pregnancies that have been identified as high risk by a prior screening test. It is usually invasive with risk of miscarriage .

6. Difference between prenatal screening and diagnostic tests
Women at high risk
All women
Population tested
To diagnose abnormality
To Select a high risk group
Purpose of test
Ultrasound
Amniocentesis
Chorionic villous sampling
cordocentesis
Maternal history
Maternal biochemistry
Maternal virology
Usual method of testing
Patient aware of potential risks
Diagnostic test should be available
Prerequisite to test
Small risk of miscarriage from invasive test
Anxiety of a screen positive result
Risk of test

7. Prenatal diagnostic tests can be divided into:
1-non-invasive tests ultrasound scanning
 maternal blood sampling
2- invasive tests  Amniocentesis
 chronic villus sampling
and placental biopsy
 Fetal blood sampling
 Fetoscopy

8. 1-Non invasive prenatal diagnosis
Ultrasound scan
At boking (11-14 weeks)
Anomaly scan at weeks
Maternal serum tests
Free fetal DNA can be extracted from maternal blood to determine fetal blood group in cases of alloimmunization , or to determine the sex of the fetus in X- linked disorders.
Other studies
3 dimensional ultrasound scan and fetal MRI this permit the increased resolution required for certain fetal malformation like cleft lip and palate.

9. 2- Invasive prenatal diagnostic tests
Cordocentesis
Chorion villous sampling
amniocentesis
20-40
10-40
15-40
Gestation (weeks)
Transabdominal
Trans abdominal / trans cervical
Route
Fetal white blood cells
Trophoblast cells
Fetal fibroblast
Cells sampled 1
Procedure related risk of miscarriage (%)
Not needed
24-48 hours
FISH for chromosomes 13, 18, 21 and XY, hours
Direct karyotype result
1-2 weeks
2-3 weeks
Culture karyotype result
None 1%
Mosaicism rate on karyotype

10. Structural anomaly (Neural tube defects)
Are most common major abnormalities . It occurs due to defect in formation of neurl tube defects during embryogebrsis.
The aetiology is multi - factorial ( envirumental , genetic , pharmacological and geographical factors implicated.
Anencephaly ( lethal ) , encephalocele ( prognosis related to size of defects )
Spina bifida usually affect spinal cord at the caudal level. The local effects (paralysis of legs, urinary and fecal incontinence ) depend on spinal levels and the number of spinal segments affected in the lesion.
When a parent or previous sibling has had an NTD, the risk of recurrence is 5-10%.

11. Screening test Ultrasound
1- in first trimester can diagnose anencephaly , encephalocele.
2- At 20 weeks anomaly scan for spina bifda and hydrocephalous.
Mid trimester maternal serum alpha - fetoprotein ( AFP ) levels are increased in pregnancies affected by open NTDs.
Diagnostic test
In the past, in case of screen positive women, they referred for amniocentesis to detect the presence of acetylcholinestrase in the amniotic fluid.

12. Prevention of neural tube defects:
Periconceptional folate supplementation to the mother reduce risk
folic acid should be given for at least 3 months prior to conceptionand for the first trimester of pregnancy.
The dosage is 400 mcg for primary prevention and 4 mg for
prevention of NTD in :
Women with previously affected baby with NTD
with type 1 diabetes mellitus
in mother use antiepileptic drugs
multiple pregnancy
mother with hemoglobinopathies .

13. Structural anomaly (Congenital heart disease) CHD
Anomalies of the heart and majors arteries are common heterogeneous
They range from asymptomatic to the lethal one or that required surgery
Risk factor:
When a previous sibling or father is affected by CHD
Offspring of women with type 1 diabetes.
Drugs like lithium
Viral infection like rubella
Chromosomal abnormality
Can be detected by ultrasound at 20 weeks

14. Chromosomal abnormalities (Downs syndrome)
Down's syndrome (trisomy 21 ) it is an abnormal female gametogenesis either due to:
Non dysjunction in meiosis (90 %)
Un balanced translocation (6 %)
Mosaism (4%)

15. Screening Diagnostic test Maternal age and history
Increase risk with advanced maternal age. Age over 35 years old 1:750 , previous history of Down's 1:100 these should offer prenatal diagnosis.
2. Maternal serum biochemistry
This iclude first trimester test of maternal serum HCG , estriol , inhibin ,PAPP-A , together with second trimester alpha feto protien (all are reduce except HCG)
3-Ultrasound for nuchal translucency
Measurement of subcutaneous collection of fluid in nuchal (behind neck) region of fetus at weeks gestation, it increase in affected fetus
Diagnostic test
Women with positive screening test are offered invasive tests
(Amniocentesis and chorionic villus sampling ) .

16. Genetics disorders (hemoglobinopathies )
Sickle cell anaemia and thalassaaemia are both autosomal recessive with a risk of 25% affection of the offsbling
Screening of at high risk populations (african in sickle cell anaemia and Mediterranian in thalassaemia) is by maternal serum electrophoresis
Prenatal diagnosis by any invasive test (amniocentesis , CVS ,cordocentesis ) to take fetal cell for DNA study .

17. Cerebral calcification Features of congenital infection
Congenital infections
parvovirus
toxoplasmosis
Cytomegalovirus
Rubella
Infected children
Cat-litter
Under-cooked meat
Infected individuals
Source
Aplastic anaemia
hydrops
Microcephaly
Ventriculomegaly
Cerebral calcification
Heart defects
Growth restriction
Hepatomegally
Thrombocytopenia
Mental retardation
Cataracts
Features of congenital infection