Concerning vaginal ultrasound imaging in early pregnancy,

1. absence of cardiac activity in an embryo of 3 cm reliably indicates a non-viable pregnancy.

2. an intrauterine gestational sac is reliably seen 20 days from ovulation.

Concerning ultrasound in pregnancy,

3. ultrasound markers may be detected during a second-trimester scan in 70% of fetuses with Down syndrome.

4. trisomy 18 is the chromosome abnormality most commonly associated with choroid plexus cysts.

5. most fetuses with a nuchal translucency of 2.5 mm or more are normal.

The following conditions can be detected by ultrasound screening of the fetus:

6. syndactyly.

7. Edward syndrome.

8. congenital heart block.

With regard to fetal lumbar meningomyelocele,

9. the extent of neuromuscular disability can be predicted antenatally.

10. there is a recognised association with renal anomalies.

The following conditions are characteristically associated with oligohydramnios:

11. fetal imperforate anus.

12. talipes equinovarus.

The following conditions would be expected to conform to the pattern of inheritance shown in Figure 3:

13. Huntington's chorea.

14. Phenylketonuria.

15. Tay Sachs disease.

Recognised causes of vomiting in the second trimester of pregnancy include

16. necrobiosis in a fibroid.

17. trophoblastic disease.

The following statements regarding multiple sclerosis in pregnancy are correct:

18. Epidural anaesthesia will not precipitate a relapse.

19. The second stage of labour should be shortened.

20. It has no effect on the long-term prognosis of the disease.

The following have a recognised association:

21. prolonged maternal intravenous infusion : neonatal hyponatraemia.

22. epidural analgesia : reduction of fetal heart rate variability.

23. migraine : pregnancy-induced hypertension.