 So, now we start with our last talk in the series of fetal heart assessment during anomaly scan which is a 3 vessel trachea view. We saw the checklist of our 4 chamber view which was pretty big but we have mastered it now. We have seen the checklist of our outflow track views. So, once you have done these 2 views we come to a 3 vessel view. A 3 vessel view is obtained in a transverse plane of the fetal upper thorax. One has to move the transducer little kefilad from the 4 chamber view to obtain this 3 vessel view. What you see in this view is the main pulmonary trunk appears in an oblique section. The ascending aorta and the superior vinakeva are seen in a transverse section. So, in short when you start in the upper thorax this is the right side, this is the spine and this is the left side. So, when you start from right to left this is a smaller circle that is the SVC. Then you see the aorta which is a relatively bigger circle as compared to SVC and then you see a comma shaped structure which is a pulmonary artery. So, you move little more cranial to the 3 vessel view and then you start getting a 3 vessel trachea view. Here you will see the aortic arch and ductile arch merging together with an acute angle between them. Both the arches are located to the left of the spine and trachea and this is an important anatomic landmark. Colour Doppler reveals the entero posterior flow in both arches and normally there should be no vessel crossing posterior to the trachea. So, when you see here again this is the spine this arrow points to the trachea. This is the SVC, aorta and pulmonary artery and this is the arch. This is the aortic arch and this is the ductile arch. So, they usually form a V shape structure like this which is to the left of spine and to the left of trachea. So, this is an important landmark in the 3 vessel trachea view. So, if you put on the colour it usually shows entero posterior flow. What do you mean by that? This is the spine which is posterior and this is the sternum. This is the anterior portion. So, the blood flow always goes from the ventricles to the great arteries and that is why they go posteriorly and that is why since this is the colour scale you are seeing both these arches in the same colour and that is in blue. The SVC will be seen in red because it moves it takes the blood in the opposite direction and then you see the normally running subclavian artery on the right side which in fact forms a cycle handle kind of a picture or a kind of a configuration. So, the abnormalities which can be picked up on a 3 vessel trachea view can be abnormality in the vessel size, abnormality in the vessel arrangement and the alignment, the abnormal vessel number, it may be abnormal location of the transverse aortic arch in relation to the trachea, it may be abnormal functional behaviour of the arterial vessels that is a reversed flow or a turbulent flow and that will be seen only using a colour Doppler. So, this is something which tells you about the size of the vessels. This is the spine here, this is the SVC aorta and the pulmonary and this is the trachea here. So, here we know for sure that the aorta is small in size. This is another patient, this is the spine, this is the right side, you can see only 2 vessels, this is the SVC and this particular structure is the aorta and this in fact has an abnormal configuration or an abnormal shape, it is in an oblique or a curved kind of a fashion. So, then again this tells you that there is something wrong with the outflows and you should scan the outflow track views more carefully. This is the SVC, the aorta and the pulmonary artery. In fact, they should form a V which is to the left of the trachea. Instead of that they are forming a U kind of a structure behind the trachea, normally you do not see anything going behind the trachea. So, this is a right sided aortic arch. This as we saw that the flow in the 3 vessel trachea view is always from the anterior to the posterior direction. So, the pulmonary artery is showing a proper direction of the flow, but the aorta is showing a reversed flow. That means it is filling through the ductus arteriosus. This particular structure where they meet is the ductus arteriosus. So, there has to be something wrong in the left ventricular outflow track or something wrong with the left ventricle. Then there are some miscellaneous structures which can be seen on 3 vessel trachea view. It is aberrant right subclavian artery. We can do assessment of thymus in the 3 vessel trachea view. And we can do aortic isthymus Doppler velocimetry in FGR fetus. As you can see here, this is again the SVC, aorta and pulmonary. And this isoechoic structure, a box kind of a structure which is seen here is the thymus. So, this gets outlined by these 2 internal mammary arteries. This is the sternum here. So, this is called a thigh box. This was described by Pallidini and this particular structure tells you that the thymus is normal because it forms a box kind of a structure. So, that is a thigh box. The aberrant right subclavian artery is something like this. You can see the pulmonary and aorta and this is the ductus arteriosus. And it is to the left of the spine. But you will see a vessel which is going behind the trachea. That is why this is the aberrant right subclavian artery. So, this comes to the end of our series of videos about the fetal heart assessment during a normally scan. The 4 chamber and 3 vessel trachea view are easy to obtain. And outflow track views can be learned with practice. Thank you.