10. Gestational age:

a.	the expected date of delivery can be calculated using Naegele's formula	True
b.	is accurately assessed by vaginal examination between 10 and 12 weeks	False
c.	is accurately assessed by abdominal examination between 14 and 18 weeks	False
d.	can be assessed by measurement of sac size between 6 and 8 weeks	True
e.	can be assessed by measurement of crown rump length in the second trimester	False

Naegele's formula is the ancient one of adding three Wednesdays, two Thursdays and the number you first thought of to the LMP.

In fact, you add seven days to the first day of the LMP, take off three months and add one year.

It is accurate if conception occurred two weeks after the first day of the LMP, but, as you well know, many factors make this unreliable.

Clinical examination is very poor at assessing gestation.

Measurement of the sac size is a good indicator of gestation.

Very early measurements can be made using trans-vaginal ultrasound.

Second trimester measurement uses the bi-parietal diameter. Crown rump length is used in the first trimester.