Findings:

Normal evaluation of fetal heart at 12 weeks antenatal scan is evaluated using a 9L linear transducer which give better resolution than a curvilinear transducer. But, its use is limited due to poor penetration.

Four chamber heart, outflow tracts (RVOT, LVOT), inter-atrioventricular septum, atrio-ventricular valves can be seen on colour doppler.

Discussion:

Normal views to be seen at NT scan are:

• 4 chamber view
• 3 vessel view
• 3 vessel trachea view
• LVOT view
• RVOT view

Key-points:

On colour doppler any signs of regurgitation, stenosis or valvular dysplasia can be ruled out.

Any regurgitant flow on colour doppler will be seen as aliasing or mixing of colours.  

On 3 vessel and 3 VT views, PLSVC or supracardiac TAPVCs can be diagnosed at NT scan.

Ductus venosus must be studied with fetal heart during NT scan.