Tricuspid flow

The heart is made up of four chambers: right and left ventricles and right and left atria. There is a tricuspid valve between the right ventricle (RV) and right atrium (RA) and a mitral valve between the left ventricle (LV) and left atrium (LA). Normally blood goes across the valves from the atria to the ventricles. In some cases the valves may be leaky so that a small amount of blood escapes from the ventricles back to the atria (regurgitation)  

• The blood flow across the tricuspid valve produces a characteristic waveform which can be either normal or abnormal (tricuspid regurgitation)
• At 11-13 weeks abnormal waveform is observed in about 1% of chromosomally normal (euploid) fetuses and in 55% of fetuses with trisomy 21. However, the vast majority of fetuses with abnormal waveform are normal and have a normal pregnancy outcome