Pregnancy Loss

Question 1

What are the most common abnormalities seen in first trimester pregnancy losses?

Answer 1

Aneuploidy seen in 50% of losses, of which:
- 30% trisomy 16, 10% trisomy 22.
- other trisomies include 21, 15, 13, 2 and 18.
Also see 45,X in 20%, triploidy in 16% and tetraploid in 6%.
Structural abs seen in 4%.

Question 2

What are the most common abnormalities seen in second trimester pregnancy losses?

Answer 2

Abnormality rate is ~20% and moves towards the usual trisomies of 13, 18 and 21.

Question 3

What is the chromosome abnormality rate for third trimester pregnancy loss?

Answer 3

Only ~5%, lower if fetus is a ‘fresh’ still birth and there are no malformations.

Question 4

From which parent does the trisomy usually originate?

Answer 4

Most commonly of maternal origin.

Question 5

What guidelines determine our new analysis strategy?

Briefly what do they state?

Answer 5

The ‘Green Top’ guidelines.

State that cytogenetic analysis should be performed on POC of the 3rd miscarriage and subsequent miscarriages only.