Gestational age | Purpose of ultrasound examination and frequency |
11 to 14 weeks | - One examination for:
- Assessment of gestational age and estimated date of delivery
- Assessment of chorioamnionicity
- Measurement of nuchal translucency*
|
16 AND 18 weeks | - Fetal size
- Early fetal anatomic survey, including presence and size of fetal bladders
- MVP of amniotic fluid
- Doppler measurement of MCA-PSV
- Doppler measurement of end-diastolic velocity in the UA
- Assessment for PDE
|
20 weeks | - Fetal size
- Detailed fetal anatomic survey, including presence and size of fetal bladders
- MVP
- Doppler measurement of MCA-PSV
- Doppler measurement of UA end-diastolic flow velocity
- PDE
- Evaluate placental cord insertion sites (proximate cord insertion is defined by a distance between cord insertions below the fifth percentile for gestational age or by 3.3 to 4.0 cm at any gestational age)
|
20 to 22 weeks | - Transvaginal ultrasound measurement of cervical length
- Fetal echocardiogram
|
22 to 32 weeks | - Serial examinations of fetal growth every 4 weeks
- Serial examinations of the following every 2 weeks:
- MVP
- Presence and size of fetal bladders
- Doppler measurement of MCA-PSV
- Doppler measurement of UA end-diastolic flow velocity
- PDE
|
32 to 36 weeks | - Continue serial examinations of fetal growth every 4 weeks
- Weekly examinations:
- Biophysical profile score
- Doppler measurement of MCA-PSV
- Doppler measurement of UA end-diastolic flow velocity
- PDE
|