 Today we will see the 11 to 14 week scan. So the torque is divided into following points the need for the early anomaly scan, the timing of early anomaly scan, which structures can be seen and which cannot be seen which is very important. So in this first video we will see NT, NB, DV and TR and in the next video we will see the system by scanning of different structures what we do as a part of early anomaly scan. So what is observed is that major life-threatening anomalies are picked up early or at least give some sonographic clue to the abnormality and that's why we should scan all patients between 11 to 14 weeks. So the changing concepts are now to do one scan at 11 to 14 weeks as early anomaly scan and then the later scan at 18 to 20 weeks. What started as the NT, NB scan has evolved into in fact structural defects and with the help of serum biochemistry we can also diagnose the risk of pre-eclampsia, diabetes, pre-term delivery etc. So it is not just a nuclear scan but 11 to 14 weeks early anomaly scan. What is very important at this time to know is that even though we do it between 11 to 14 weeks there are different things at 11, 12 or 13 weeks. If you scan a patient between 11 to 12 weeks what happens is of course NT can be measured but structural analysis is difficult what we will see in the next video and the gestational age may be say 11 weeks four days but bio-metry maker respond to just 11 weeks one day because plus minus 3 to 4 days is always in an acceptable range. So as you can see here the CRL is just 4.3 and the gestational age is 11 weeks one day. So practically it is not even more than 45 millimeter which is not actually good for doing the NT scan. If we do it between 13 to 14 weeks what happens is of course structural analysis is much better but fetus sometimes remains in the vertical orientation all throughout the scan which is not good for NT and again the same point holds true that the gestational age may be 13 weeks five days but the bio-metry maker respond to 14 weeks three days and then you've lost that window of 11 to 14 weeks scan. So the best time is between 12 to 13 weeks the structural analysis is also good the horizontal orientation of the fetus is obtained most of the times which is good for NT and even if bio-metry and gestational age do not match with each other say there is a difference of 3 to 4 days here and there it will still fall in the range of the 11 to 14 weeks scan. Now we come to the next point what are the anatomical structures which can be seen the calvarium ossification is always there I have deliberately said it as between 12 to 14 weeks cerebral midline and phax is always seen the cerebellum you cannot comment upon the corpus callus is not formed by then gyri salchi you cannot comment upon the spine the neural tube defect of course there are indirect signs to detect the neural tube defect but the direct visualization of the spine or effect is always plus minus the four chambers and outflow again are seen most of the times between 12 to 14 weeks but depending on the patient position the body habit is the fetal position it may or may not be seen always the stomach is always seen between 12 to 14 weeks the abdominal wall is always intact between 12 to 14 weeks kidney and bladder is again plus minus the kidneys become difficult to visualize trans abnormally bladder is most of the time seen beyond 12 weeks and we are able to see it in all our anomaly scans if we do it between 12 to 14 weeks long bones are all seen in fact is seen better if all four limbs and all three segments of the limbs can be seen between 12 to 14 weeks so it's a good image of course the nasal bone the NT seen well but we all know that the quality of the image depends on the technical skills and what are the problems there is a small size of the fetus the uterus position is still in the pelvis it has not become an abdominal organ still then the flat maternal abdomen limits the intonation angle if the uterus is retroverted again it is difficult to visualize the fetus and the focal myometrial contractions probably the biggest enemy as you can see here there is a contraction here and this baby is almost in a vertically oriented position and because of this contraction the baby is not getting enough space to move and the best thing is to wait for some time you can't really do anything about it this is the cervix and there is the uterus which is retroverted so again in these cases the fetus is too much down in the pelvis and then it becomes difficult to get a very good NT position but of course there are some solutions increased mobility of the fetus overcomes this problem as you can see during this scan between 11 to 14 weeks the fetus really moves a lot completely upside down also asking the mother to cough walk eat turn on one side all these maneuvers can help sometimes making the patient the mother eat something and then calling her after one or two hours helps and looking at the status of the bladder helps in changing the fetal position if the bladder is completely empty the fetus is too much low in the pelvis you can make the bladder distant and then get it relatively up and then scan the fetus so as you can see the myometrial contraction has gone and then after some time we have got a fairly good image this was the completely retroverted uterus but we made the bladder full and then we have got a relatively better image so these are the points which can be remembered the image optimization can be improved by choosing the high frequency transducer considering using a linear or endovaginal transducer whenever possible sometimes use the other hand to gently manipulate the uterus you can narrow the image sector you of course have to magnify the region of interest and use one focal zone that improves the sharpness and the clarity of the image so in this video we will see about the nuclear translucency the nasal bone the TV and the tricuspid regurgitation the NT is a collection of fluid under the skin behind the neck that can be measured by ultrasound the NT is calculated between the CRL of 45 to 84 millimeters and these are the six points on which we analyze our image so how do we do that the magnification should be such that only the upper thorax and fetal head should be included as you can see here this is the upper thorax and the head which is included and the magnification should be such that each slight movement of the caliber produces only a 0.1 millimeter change in the measurement how do you know it is a two midsat section but tip of the nasal bone should be seen as you can see here and the rectangular shape of the palate and non-visualization of the psychomatic process so this space is very clear and there is no bony structure seen there so you know this is a two midsatical position the neutral fetal position can be ascertained by seeing the head in line with the spine as you can see here and there is a clear space the fluid between the chin and the thorax so you know that this is a neutral position caliper placement has to be inner to inner and this is the correct position for the caliper the maximal lucency that is the widest part of the lucency should be measured and the thin nuclear membrane should be clearly seen posteriorly and this is very important is to distinguish between the fetal skin and the amnion which may be still posterior to that so what are the structures what we see in the nuclear section is this is the nasal tip this is the nasal bone this is the phax the equationic structure this is the dienkephalon the lucency this is the palate which is seen and that is the nuclear membrane which is seen posteriorly more than one measurement should be taken and the maximum one that meets all the criteria should be recorded sometimes there may be an umbilical cord around the neck and that can falsely increase the NT so ideally the NT above and below should be measured and then the average of two measurements can be taken and nowadays some machines have come up with the auto NT measurement as you can see here you can you know put a box there and the machine will take the maximum measurement properly but then again for this you have to have a very correct image and sometimes what you scan and what you measure eyeballically becomes much better the NT interpretation the median and the 95th percentile at CRL of 45 are 1.2 and 2.1 millimeters and the same values at the higher CRL that is 84 millimeters are 1.9 and 2.7 millimeter so the general value of 3 millimeter and more should be applied more cautiously if you have a CRL of just 48 millimeters then maybe the value which is 2.5 millimeter may be at 95 percentile and above that's why you have to look at the normograms you have to see the online calculators at the FM website and perinatology website to know the exact percentile for that particular CRL and you should not just generalize the measurement as anything which is 3 millimeter and more only as a normal thing we all know the NT is high in chromosomal abnormalities non-chromosomal syndromes in cardiac defects in fetal anemia hypoproteinemia and in fetal infections also so with that we come to the nasal bone how do we take the nasal bone image this is also between 11 to 13 big six days nasal bone first appears at a CRL of around 42 millimeter and increases linearly with gestation so again there has to be a good magnification only the head and upper thorax are seen a mid sagittal section is a must you have to be careful to see that the ultrasound transducer should be parallel to the direction of the nose you can see this nasal bone which is almost parallel to the direction if the fetal face is slightly in a flexion mode and if you don't really insunate the nasal bone like this in a parallel fashion then you may get a false impression of either the nasal bone being present or absent very important point is the equigenicity of the nasal bone should be more than the equigenicity of the skin overlying it and that's why we say there is an equal sign here the top line is skin the bottom line is nasal bone and the third line or a dot is the tip of the nasal bone the non-ossified nasal bone has a strong likelihood ratio for Down syndrome it can also be a marker for other syndromic conditions in which mid-face hypoplasia is noted so it is not that it is just an indication of Down syndrome but some other skeletal dysplasia's or some other syndromic conditions also sometimes what happens is it is very difficult to make out the equigenicity of the skin and the nasal bone and they may appear with same equigenicity or sometimes you're not very sure whether the nasal bone is separately seen or not so what one can do is by changing some presets or some penetration level putting off the harmonics or maybe putting off the cri sri or in some machines the x-rays and sonocity technology so sometimes if you put it off you can see in fact the equigenicity of the nasal bone very well and you are sure that the nasal bone is present that sometimes you should know from your machine presets which gives you the best image and then once you know that as you can see here there is only one equigenic line seen and the nasal bone is absent even here even though you see it as two lines you know that this line is in fact less equigenic than the top line and there is non ossification of the nasal bone with that we come to a ductus vinosus again the gestational age must be 11 to 13.6 you should take a sagittal magnified section of the abdomen fetus should be still you should put the color Doppler on and look at the area of maximum aliasing or the one which is giving you the brightest signal and the pw sample width whatever smallest possible on our machine should be adjusted and you should keep that pw sample exactly at the brightest signal and the intonation angle should be less than 30 degrees so as you can see here you are seeing the brightest signal here so you will use the smallest pw width and you will put it at the brightest point and then you will get a signal of the ductus vinosus better so normal dv flow has the ventricular systole s-wave the diastole d-wave and always a forward flow during atrial contraction that is the a-wave and the reversal of the a-wave is actually the abnormal dv flow the waveform is contaminated sometimes from the adjacent veins or the hepatic archy if the pulse Doppler sample is large more than one millimeter or which is not placed exactly on the ductus vinosus not placed exactly at the bright structures as you can see here that this particular section is actually the venous kind of a signal which is coming which is coming even here and then these are the ones which should be taken care of with that we come to tricuspid regurgitation again the gestational age must be between 11 to 13.6 you have to take a magnified apical four chamber view of the fetal heart color Doppler actually is not really useful so early ingestation it is unreliable for the diagnosis of regurgitation in the first trimester as opposed to second trimester here the pw sample volume should be more 2 to 3 millimeters and it is positioned across the tricuspid valve again the incineration angle should be less than 30 degrees to the interventricular septum so this is a normal tv flow sometimes you get the aortic or pulmonary artery flow because the fetus is very small the heart is very small and when you are putting the incineration width of around 2 to 3 millimeters it is bound to take some signal from the surrounding arteries but remember it is always less than 60 centimeters per second and as opposed to that there is a tricuspid regurgitation where you can see here the velocities are in fact more than 180 almost reaching to 200 210 and then this is more than 60 centimeters and this was almost more than 180 centimeters so we know for sure that this is the tricuspid regurgitation so with tricuspid regurgitation also there is association with chromosomal aneuploidies the cardiac defects raised anti associated with tr will definitely increase the risk of cardiac effects and then a tvs fetal echo should be done whenever possible so with this we end this video here and in the next video we will talk about structural analysis of the fetal structures