Prenatal Diagnosis

Definition of Prenatal Diagnosis

An aspect of science that employs a variety of techniques to determine the health and condition of an unborn baby using invasive and noninvasive techniques

Screening in Prenatal Diagnosis

1. History

2. Exam

3. Tests include: •Non invasive tests

   –Maternal biochemistry

   –Ultrasound

   –Cell free fetal DNA

What do you look out for in history and exam?

• History

–Maternal age

–Prev hx of anomaly

–Maternal cong anomaly –

_ med disorder

–Maternal drug use

–Recurrent miscarriage

-Genetic makeup of the parents

• Examination

–Congenital anomaly –Chronic medical disorder

Maternal biochemistry measures?

• Maternal serum free b-hcg

• Serum alpha feto-protein

• Inhibin-a

• Pregnancy associated plasma protein-a [papp- a]

•Serum unconjugated estriol

Down syndrome biochemistry

High: Beta HCG, inhibin A

Low: PAPP-A, AFP, unconjugated estriol

Down syndrome biochemistry

High: Beta HCG, inhibin A

Low: PAPP-A, AFP, unconjugated estriol

What is Nuchal translucency and when is it done?

NT- defined as the sonographic appearance of subcutaneous accumulation of fluid behind the fetal neck in the first trimester of pregnancy

At 13weeks

When is fetal anomaly scan done?

20-22wks

Diagnostic tests

•Pre-implantation genetic diagnosis

•Cell free fetal dna

•Other invasive tests

–Fetoscope

–Amniocentesis

–Chorionic Villous Sampling

_Cordocentesis

_ Fetal Tissue Sampling

When is amniocentesis done?

culture takes?

Results when?

What sample bottle?

How many mls?

What is done with sample?

16wks

2-3wks

18wks

Plain bottle

15-25mls

FISH or Karyotyping

When is CVS done?

Samples what?

Routes?

What happens when done before 10wks?

11-13wks

Placental tissue

Trans abdominal or transcervical( for low lying placenta)

Associated with limb deformities

What is cordocentesis?

AKA?

When is it done?

A procedure in which samples of fetal blood are taken directly from fetal vein usually under USS guidance.

Percutaneous Umbilical Vein Access

From 16weeks!

Complications of Invasive Procedures

• Miscarriage

• Vaginal bleeding

• Amniotic fluid leakage

• Rh isoimmunization

• Chorioamnionitis

• Transmission of HIV

• Limb deformities

• Mosaicism

What happens after diagnosis?

1. Genetic Counseling

2. Termination depending on severity, legal surrounding, culture and belief.