Applied Embryology

Question 1

What are some of the most commonly seen birth defects?

Answer 1

• Congenital Heart Defects

- Neural Tube Defects

Question 2

What is a teratogen?

Answer 2

An environmental ‘exposure’ (e.g. a drug or substance or infection) to which the mother is exposed during pregnancy

May detrimentally affect the developing embryo/fetus in utero

May lead to structural or functional abnormalities or even in utero death

Question 3

What effect can teratogens have on the developing fetus?

Answer 3

Death 
Learning difficulties 
Sensory deficient 
Structural Abnormalities 
Growth defects 
etc.

Question 4

What impact does the timing of teratogen exposure have?

Answer 4

Adverse effects can occur at any stage in utero.

1st trimester
- Structural defects can occur when organogenesis is occuring
Greatest risk is between week 3 and 11

Functional or growth defects are more likely is exposure is after 12 weeks.

Question 5

What are some of the risks for foetal alcohol syndrome?

Answer 5

Binge drinking: five or more units on one occasion.

Regular binging around conception and early pregnancy is harmful.

Heavy drinking is also related to unprotected sex - can result in unplanned pregnancy and STIs.

Question 6

What is the classical triad for congenital rubella syndrome?

Answer 6

Sensorineural Deafness
Eye abnormalities - esp. retinopathy, cataracts, micropthalmia
Congenital Heart Disease - esp. pulmonary artery stenosis and patent ductus arteriosus.

Question 7

What defects are associated with varicella infection in pregnancy?

What timing poses the greater risk?

Answer 7

• Limb hypoplasia
• Skin scarring
• Eye defects
• Greatest risk in the 2nd trimester.

Question 8

When does cardiac development in the foetus occur?

Answer 8

Weeks 3-7

HB seen on USS at 6 weeks.

Question 9

What are some of the common causes of caridac defects?

Answer 9

Drugs such as warfarin.

Infections

Genetics

(Cardiac development is early in pregnancy)

Question 10

What impact can opiate medications taken in late pregnancy have on the neonate?

Answer 10

Respiratory distress.

Question 11

What effect do teratogens tend to have late in pregnancies?

Answer 11

Effect of brain
Effects on skeleton
Growth Restriction

Question 12

With what patients is preconception conselling vital?

Answer 12

Epilepsy

Diabetes

Women on anticoagulants

Women with congenital anomalies

Antihypertensives

Question 13

Why is folic acid in the diet advised?

Answer 13

Decrease the incidence of neural tube defects.