Prenatal Diagnosis

Question 1

Non invasive tests

Answer 1

1. Ultrasound Scan
2. Maternal Blood tests

Question 2

Invasive tests

Answer 2

Chorion Villus Biopsy (CVB)
Amniocentesis
Cordocentesis

Question 3

Chorion Villus Biopsy is used to …

Answer 3

check karyotype of fetus

Question 4

Chorion Villus Biopsy can be used to diagnose

Answer 4

1. Down Syndrome
   2.Cystic Fibrosis
2. Thalassemia

Question 5

Amniocentesis used to diagnose

Answer 5

1.Down Syndrome
2. Cystic Fibrosis
3.Thalassemia

Question 6

Cordocentisis used to diagnose

Answer 6

Alloimmune thrombocytopenia

Question 7

An U/S scan followed by an invasive procedure can be used for what fetal issues?

Answer 7

1. Congenital diaphragmatic hernia
   2.Ventriculomegaly
   3.Exomphalos
2. Dued. Atresia

Question 8

What is done in a Chorion Villus Biopsy?

Answer 8

Sample of fetal trophoblastic cells is taken.

Question 9

Method of Chorion Villus Sampling

Answer 9

1.pass needle through abdominal wall into placenta under U/S guide
2. Pass catheter/biopsy forceps through cervix into placenta w/ U/S guide.

Question 10

Why should an U/S scan be done before a CVB procedure?

Answer 10

1. Ensure Viability
2. Confirm Single Preg.
3. Confirm G. Age (+10weeks)
   4.Localize Placenta

Question 11

What is an Amniocentesis Procedure?

Answer 11

Procedure done to take sample of amniotic fluid containing cells.

Question 12

When can an Amniocentesis procedure be done?

Answer 12

+15wks

Question 13

Method of Amniocentesis

Answer 13

Needle passed through abdominal wall into amniotic cavity under U/S guidance and fluid is aspirated (15-20mL)

Question 14

Advantage and Disadvantage of CVB over Amniocentesis

Answer 14

CVB can be done earlier than amniocentesis.
CVB has higher miscarriage risk (2%)

Question 15

What is a Cordocentesis procedure?

Answer 15

Acquire fetal blood sample for rapid full culture of karyotype.

Question 16

Most common indication for cordocentesis

Answer 16

Check for fetal platelet count in suspected alloimmune thrombocytopenia.

Question 17

Method of Cordocentesis

Answer 17

Done +20wks.
Needle passed into Umbilical cord where it enters placenta under U/S guidance.

Question 18

The most common reason for prenatal invasive tests is…

Answer 18

Down Syndrome

Question 19

Test used for Down Syndrome and when

Answer 19

Combined test @ 11-14wks

Question 20

Combined Test

Answer 20

@11-14wks
1. U/S scan to measure nuchal lucency
2. Maternal Blood test for HCG and PAPP-A (preg. associated plasma protein-A)

Question 21

Define Nuchal Lucency

Answer 21

Thickness of pad of skin in neck region of fetus

Question 22

Risk of down syndrome is based on

Answer 22

maternal age
combined test results