Respiratory Medicine - Embryology of the diaphragm and diaphragmatic hernia

Question 1

Embrolygically when is the diapragm formed?

Answer 1

The diaphragm is formed between the 5th and 7th weeks of gestation through the progressive fusion of the septum transversum, pleuroperitoneal folds and via lateral muscular ingrowth.

Question 2

What are the two types of diagpramatic hernias?

Answer 2

• Morgagni
• Bochdalek hernia

Question 3

What is a Morgagni hernia?

Answer 3

• Anteriorly located
• Minimal compromise on lung development
• Minimal signs on antenatal ultrasound
• Usually present later
• Usually good prognosis

Question 4

What is aBochdalek hernia?

Answer 4

• Posteriorly located
• Larger defect
• Often diagnosed antenatally
• Associated with pulmonary hypoplasia
• Poor prognosis

Question 5

What are the most common type of hernia?

Answer 5

• The posterior hernias of Bochdalek are the most common type and if not diagnosed antenatally will typically present soon after birth with respiratory distress.
• The classical finding is that of a scaphoid abdomen on clinical examination because of herniation of the abdominal contents into the chest.

Question 6

What are the chromosomal abnormalities associated with Bochdalek hernias?

Answer 6

• Trisomy 21 and 18.
• Infants have considerable respiratory distress due to hypoplasia of the developing lung.
• Historically this was considered to be due to direct compression of the lung by herniated viscera.
• This view over simplifies the situation and the pulmonary hypoplasia occurs concomitantly with the hernial development, rather than as a direct result of it.
• The pulmonary hypoplasia is associated with pulmonary hypertension and abnormalities of pulmonary vasculature.
• The pulmonary hypertension renders infants at risk of right to left shunting (resulting in progressive and worsening hypoxia).

Question 7

Diagnostic work up?

Answer 7

• chest x-rays/
• abdominal ultrasound scans
• and cardiac echo