Tricuspid Regurgitation

Tricuspid regurgitation is the flow of blood back into the right atrium during ventricular systole. In the normal fetus blood normally flows from the atrial chambers into the ventricles through two valves. The tricuspid valve allows blood to flow from the right atrium into the right ventricle and the mitral valve allows blood to flow from the left atrium into the left ventricle. After the ventricular chambers fill with blood they contract or squeeze. This is called ventricular systole. During this process the tricuspid and mitral valves close, not allowing blood to re-enter the right and left atrial chambers. Dr. DeVore first described the association between tricuspid regurgitation and Down syndrome in second-trimester fetuses. Subsequent to his studies, investigators found that tricuspid regurgitation present in the first-trimester fetus also increased the risk for Down syndrome and other chromosomal abnormalities. The images below this text illustrate this finding.

Using color Doppler ultrasound, the normal 4-chamber view (left image) does not demonstrate blood flow back into the right atrium during ventricular systole. The image on the right illustrates a blue jet of blood entering the right atrium during ventricular systole. This is tricuspid regurgitation.

This illustrates a pulsed Doppler image confirming the presence of the tricuspid regurgitation. In the normal fetus there is no blood flow into the right atrium during ventricular systole. However, when tricuspid regurgitation is present, blood flows back into the right atrium (blue waveform).

Medical Literature

1:	Faiola S, Tsoi E, Huggon IC, Allan LD, Nicolaides KH. Likelihood ratio for trisomy 21 in fetuses with tricuspid regurgitation at the 11 to 13 + 6-week scan. Ultrasound Obstet Gynecol. 2005 Jul;26(1):22-7.	Related Articles, Links
2:	Nicolaides KH, Spencer K, Avgidou K, Faiola S, Falcon O. Multicenter study of first-trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk-orientated two-stage first-trimester screening. Ultrasound Obstet Gynecol. 2005 Mar;25(3):221-6.	Related Articles, Links
3:	DeVore GR. The role of fetal echocardiography in genetic sonography. Semin Perinatol. 2003 Apr;27(2):160-72. Review.	Related Articles, Links
4:	DeVore GR. Trisomy 21: 91% detection rate using second-trimester ultrasound markers. Ultrasound Obstet Gynecol. 2000 Aug;16(2):133-41.	Related Articles, Links