 Today, we will see a fetal eco case. This was a 37 weeks primary gravita. She came for the obstetric Doppler with reduced fetal movements. The Doppler was normal. All the parameters of Doppler were found to be normal. But what was striking was that there was little cardiomegaly and the RARV looked little more dilated as compared to the LALV. As you see these findings, you obviously want to look at the outflow tracks. You want to see whether it is a problem of left sided heart or a right sided heart. Now if you come to the outflow tracks, you will see that the pulmonary artery also is looking in fact little dilated. This is the SVC here. This is the aorta here and this is the pulmonary artery with the branching. Now the aorta does not look so small as to call it as coactation. In fact, for this gestational age, the pulmonary artery looks little more dilated. The RARV looks little dilated. So the next step is going to be to do the color Doppler. And once I put the color Doppler on, as you can see here, this is the spine. This is the left side and this is the right side. So there is a tricuspid recogitation. There is a lot of turbulence here and there is this regurgitation across the tricuspid valve. So that may be the reason for the RARV being dilated. The heart looks otherwise structurally normal. We have done the anomaly scan at 20 weeks. When scan at 28 weeks, we have seen the heart was normal up till now. So now what is the problem? Is it some functional problem and that's why the RARV is dilated. So after this, we come to the outflow tracks and we try and see what is the color flow signal in the outflow tracks. So as you can see here, there is the aorta here, the SVC here and this dilated pulmonary artery is hardly showing any flow. There is in fact very minimal flow seen across the pulmonary valve and in the pulmonary arteries. So what is then the condition? What is it that is causing this condition? This was the tricuspid regurgitation. As you can see here, very high velocity is 332. But another case again at full term, mind you the full term fetus, it is very difficult to assess the fetal heart, but again there was a mild cardiomegaly and what you can see here, this is the spine here and this is the left side. So this is the right side and there is a tricuspid regurgitation and again there was a poor forward flow in the pulmonary arteries and there was a turbulence noted at the ductus arteriosus. What is happening here is this is the spectrum at the ductus and the velocities are quite high. As you can see here, it is almost 193 centimeters per second. So this condition is showing us oligo-hydramnios, the obstetrics Doppler was normal, tricuspid regurgitation RARV was dilated, high velocity flow at ductus arteriosus reduced forward flow in the pulmonary artery and some of these cases also show the regurgitation at the pulmonary valve. So these two cases what you saw were more or less the similar findings and this finding is due to the premature ductal constriction or a closure. Now total occlusion of the ductus arteriosus is rare, constriction is more common. This happens because of maternal ingestion of prostaglandin synthetase inhibitors. Most of the times it is endomethazine and the similar drugs. Prostaglandin synthetase inhibitors are used as tocolytics in fact in the first and second trimester. That is treatment of polyhedramnios especially in the third trimester. In fact, whenever the patients are put on these endomethazine as a treatment of polyhedramnios we get the referral for fetal echo to look for the premature ductal constriction. So the risk increases with the advancing gestation. So we should avoid the prostaglandin synthetase inhibitors after 32 weeks and for a prolonged period. One good thing is that drug induced ductal arterial constriction is reversible. So as soon as you stop the treatment all the effect is going to reverse on its own. So premature ductal constriction or a closure sometimes can seem spontaneously and the diabetic mother is another risk factor. The other factors like especially the polyphenol rich products will increase the risk of ductal arterial constriction in late gestation and which are these products? Some herbal teas, dark chocolate, orange juice, red and purple grapes, strawberries and some other berries. So sometimes the mother is not even aware that she is ingested these things in excess and how the fetus reacts to it is another important factor. It is not that in all the mothers who eat these products the fetus will have these side effects but in some of them the effects are more pronounced and that of course as we saw in late gestation it is more pronounced. So what are the ultrasound findings? Grayscale ultrasound is not very reliable. At the most what you tend to see is that the RARV is little dilated. There is sometimes cardiomegaly. If you come to the outflow tracts you will see that the pulmonary artery is in fact dilated and as you come to the ductus arteriosus it looks narrow. If this condition persists, if you have not really diagnosed it on time the heart can be hypokinetic. It can be contracting very poorly so that can happen on I mean that can be seen on the grayscale findings. And of course the color Doppler is very important and the first thing that you notice is the tricuspid regurgitation. It is usually a pancystallic tricuspid regurgitation and velocities are usually more than 200 centimeters per second. As you can see here this is the spine, the left side of the heart and that is the right side. The flow across the itrioventricular valves is going to be in blue as it is away from the transducer and this is a regurgitated flow. In red what you are seeing is the tricuspid regurgitation across the tricuspid valve. If you come to the ductus arteriosus at the level of ductus arteriosus you will see a high velocity turbulent flow. The velocities at ductus will be more than 200 centimeters per second, normal being 100 centimeters per second. Usually above 140 centimeters we start calling it as a high velocity. There is also a high velocity flow diastolic velocity which is more than 35 centimeters per second and the PI typically is less than 1.9. Since the diastolic flow increases the PI is bound to reduce. Normal is around 2 at ductus arteriosus and when it is less than 1.9 we say that this is more often seen in the ductal constriction. Here is the TR. In fact you can see the velocities is as high as 340 centimeters per second. This is the velocity at the ductus arteriosus and the velocities are also high around 265 centimeters per second. So the question is where do you look for ductus arteriosus? Simple in third trimester the 3 vessel trachea view will be easy to get rather than the sagittal view of the arterial duct. So this is a 3 vessel view and we know that this is the aortic arch and that is the ductal arch and this is where there will be a ductus arteriosus where the confluence is that is where the ductus arteriosus is and that is where you will put the spectrum on and in fact it will be somewhere here and that will be showing in fact turbulence. This is a normal fetus but when you see a turbulence you will be putting your PW sample at the level of highest turbulence and you get those high velocity flow. What happens in ductal constriction is the ductus arteriosus no longer acts as a conduit of RV outflow into aorta and that is why the blood is directed towards the lungs which gives rise to pulmonary hypertension. So a close monitoring is indicated to look for right heart failure, poor contractility which may lead to high drops and if not really detected in time it may cause fetal demise. That's why if you start seeing these findings and if there is gestational age which is 37-38 weeks a good fetal maturity is there then it is better to deliver these babies. There are several complications including hyperbillirubinemia, pulmonary hypertension, necrotizing, enterocolitis and IVH are all known in the neonatal period. So neonatal morbidity also will be high. So just to summarize the ductal constriction possibility in the third trimester is to be kept in mind especially when the RARV is dilated. There is sudden oligoheteramnios, Doppler is normal, there are reduced movements and then the patient doesn't come for a fetal echo. Actually the patient comes for a routine scan at the most for the obstetrics Doppler and when you see kind of these findings it is always mandatory to look at the heart and then there are subtle clues on a grayscale ultrasound and you put the color Doppler on, you see a tricuspid regurgitation, you start looking at the outflows and you will get the turbulent flow across the ductus arteriosis. Whenever there is a ductal closure, in fact there will be a cessation of flow and you will not really see any flow coming in the pulmonary arteries or at the level of ductus so that needs to be remembered. So your awareness of this condition is very important as in third trimester the fetal echo different sections are very difficult to get so your awareness is very important.