From the Guidelines
Additional imaging studies after the 20-week anatomy scan during pregnancy are not routinely performed for all pregnant women, but may be recommended in specific situations, as supported by the American College of Radiology's appropriateness criteria 1. If the initial anatomy scan reveals concerns or if certain risk factors are present, your healthcare provider might order follow-up ultrasounds to monitor fetal growth, placental function, amniotic fluid levels, or to further evaluate potential abnormalities. Common scenarios that might warrant additional imaging include:
- Detection of structural anomalies
- Growth restriction concerns
- Multiple pregnancies
- Maternal health conditions like hypertension or diabetes
- Abnormal amniotic fluid levels
- Placental issues These follow-up scans might be standard ultrasounds, more detailed level II ultrasounds, or occasionally MRI for specific concerns, as outlined in the guidelines for second and third trimester screening for fetal anomaly 1. The frequency and timing of any additional imaging would be determined by your healthcare provider based on your specific situation, taking into account factors such as the presence of soft markers or major anomalies found on the initial US screening 1. The reason for selective rather than universal additional imaging is to balance the benefits of monitoring against unnecessary interventions, while ensuring appropriate surveillance for pregnancies with identified risk factors, as noted in the evidence-based national guidelines for the management of suspected fetal growth restriction 1.
From the Research
Additional Imaging Studies After 20-Week Anatomy Scan
- There are various imaging studies that can be performed after the 20-week anatomy scan during pregnancy, depending on the specific needs and risks associated with the pregnancy 2, 3.
- Some studies have shown that additional ultrasound scans can be beneficial in detecting fetal anomalies and growth restrictions, even after the initial 20-week anatomy scan 4, 2.
- For example, a 16-week sonographic findings study in fetuses with increased nuchal translucency and a normal array found that the intermediate 16-week ultrasound can detect the majority of structural abnormalities that are expected to be identified traditionally at 20-24 weeks 2.
- Another study on early anatomy ultrasound in women at increased risk of fetal anomalies found that a complete anatomical survey was achieved in 67% of screened fetuses between 12-17 weeks gestation, with a sensitivity of 83.3% and specificity of 94.9% for detecting anomalies 3.
Types of Additional Imaging Studies
- Ultrasound scans: can be used to monitor fetal growth and detect any potential anomalies or complications 4, 2, 3.
- Echocardiography: can be used to evaluate the fetal heart and detect any potential cardiac anomalies 2.
- Fetal biophysical profile scoring: can be used to assess fetal well-being and detect any potential complications 5.
- Other imaging studies: such as MRI or CT scans, may be used in certain situations, but are not as commonly used as ultrasound scans during pregnancy.