 Today, we will be talking about how to differentiate between SGA and FGR babies which is a very important topic, the growth disorders in pregnancy. Before you start doing that, you should know that accurate dating and assigning the correct EdD in early pregnancy is very important to determine the growth disorders later in pregnancy. We have seen this in our previous video when the gestational age matches the ultrasound biometric age, we assign the EdD as per LMP. When in early pregnancy scan, the gestational age mismatches the ultrasound biometric age, we assign the EdD as per ultrasound age and once assigned, we do not change the EdD in subsequent reports. So what is the criteria for this mismatch and this was the chart which we have seen in our previous video. So during growth scan, it is very important to always look at the early pregnancy dating scan only then you will be able to correctly diagnose the growth disorders in your subsequent scans. So if you have not really gone through the previous video, I request you to understand the concept of estimation of gestational age and assigning the EdD and then look at this video about the growth disturbances. So first we will define certain terms which are often used in the follow-up or the growth scans. The AGA or the appropriate for gestational age, the AGA fetus is the one whose size is within the normal range for its gestational age and they typically have the individual biometric parameters and or the expected fetal weight between 10th and 19th percentiles. For gestational age fetus is the one whose size is below a predefined normal threshold for its gestational age and so they typically have EFW or AC below the 10th percentile. Here we do not really take into consideration the other biometry that is BPD and FL. Here mainly the EFW and AC, these are the only two parameters which are considered. Either one of the two can be abnormal, it is not necessary to have both these parameters to be abnormal. The LGA is the large for gestational age fetus and it is the one whose size is above a predefined threshold for its gestational age and these fetuses typically have EFW or AC above the 90th percentile. So what is a macrosomia? Macrosomia at term usually refers to a weight above a fixed cutoff usually 4000 grams or some countries or some studies say it is more than 4500 grams. So if you see a fetus who at 32 weeks weighs say something like 3.4 kg which will be at around 95th centile so you will call it as the LGA baby but not really a macrosomic baby. So it is always better to label them as LGA fetuses. So this is the chart which will tell you about the AGA between 10th and 90th centile. Anything which is above 90th centile is large for gestational age and anything below 10th centile is a small for gestational age. So what is a fetal growth restriction? FGR or IUGR fetus is the one that has not achieved its growth potential. So it is a pathological smallness and not a physiological smallness. It is not small because it is meant to be small genetically because the parents are small in height or small in size but it is pathologically small. It has not achieved its growth potential. So there is a difference between the absolute size and the growth. The fetus should steadily grow during pregnancy, should increase in size during pregnancy so that is what is important. So that is why the growth velocities are important. It is important to plot the biometric graphs and it should not be just a single study but from the previous ultrasound studies if the biometrics can be plotted and compared and if this feature is available on your machine that actually helps to define the growth disorders better. Nowadays most of the machines have this feature. You should contact your application specialist and get this feature understood. So any particular studies say I do a study today and I draw this biometry plot graph but what is more important is to see the growth velocity. A fetus which is growing at 10 centile but is steadily growing will do much better than somebody who was growing normally initially and then has started falling back, falling down on the growth centiles. This will be still a worst condition because a fetus at 28 weeks which was almost at around 80th percentile at 32 weeks had come down to around 50th centile and if you see this fetus at 35 weeks it is actually come down to 15th centile. So by definition you will not even call it a small for gestation fetus but if you see it has gone down from growing at the speed of 80th centile to come down to around 50th centile. So this fetus also actually is a growth restricted fetus and that needs to be understood and in fact these are the ones which are at more or they are more susceptible to hypoxia later in pregnancy. So whenever you want to diagnose SGA versus FGR the first step is to define the smallness and we saw that that AC and or EFW less than 10 centile is a smallness. It may be only AC, it may be only EFW or it may be both these parameters may be smaller than 10 centile. So the consensus statement which was published in 2016 they defined the early versus late onset smallness. Then they discussed which parameters will be useful to detect FGR that means to differentiate between SGA and FGR and amongst these parameters which will be solitary parameters versus the contributory parameters to diagnose the growth restricted babies. So first was define early versus late. So before 32 weeks when you detect smallness it is called early onset and after 32 weeks if you detect smallness it is called a late onset. Now we come to which parameters are useful to detect the FGR. So there are biometry parameters and there are certain Doppler parameters which are the biometry parameters, the abdominal circumference and the EFW and the AC crossing centiles or the EFW crossing centiles. This is what we discussed before what we saw that the fetus which was growing say at 80 percentile has suddenly come down to 15 centile or say 12th centile is definitely crossed the centiles that means this is the FGR baby. So that needs to be understood and that is also the criteria to detect the FGR versus SGA babies. And which are the obstetric Doppler parameters, umbilical artery Doppler, the CPR and the uterine artery Doppler. What are the abnormal Doppler parameters we saw in our video on Doppler obstetric Doppler that umbilical artery PI more than 95th centile is considered abnormal, uterine artery PI more than 95th centile is considered abnormal and CPR if it is less than 5th centile then it is considered as abnormal parameter. We also saw in that previous video there are some other Doppler parameters like MCA, DV, aortic is thermos. So are they not important? No they are important in decision making about timing of delivery which will be discussed in a later section but right now we stick to umbilical artery, uterine artery and CPR for defining the FGR versus SGA. So now we saw which are the parameters which are useful to detect FGR and then we come to the solitary versus contributory parameters. Solitary parameter is a single parameter which is sufficient to diagnose FGR even if all other parameters are normal and a contributory parameter is the one which requires another parameter to be present to diagnose the FGR babies we will see this. So now you come to the small babies. Now if you see a smallness which was detected at less than 32 weeks that is early onset we know it is detected by AC or AFW less than 10th centile. Then we look at the centile if it is less than 3rd centile or if the Doppler parameter umbilical artery is absent in diastolic flow then we straight away diagnose it as FGR even though all other parameters may be normal. So this is a solitary parameter to diagnose FGR. Then early onset smallness. If you take the smallness detected which is less than 32 weeks by AC and AFW less than 10th centile but it is between the 3rd and 10th centile. So you cannot really rely on that criteria that less than 3 centile it is definitely FGR because it is between 3rd and 10th centile. So you need a contributory parameters to diagnose FGR. So which are these? One parameter of AC or AFW less than 10th centile combined with one of these Doppler parameters the umbilical artery PI more than 95th centile and or uterine artery PI more than 95th centile any one of the two or both of them. But there has to be one criteria as biometry less than 10th centile and one criteria of the Doppler. So this will be if they are there then it is FGR. If the contributory parameters if you don't see these Doppler parameters then it is SGA baby. So these are to summarize the criteria proposed by an international Delphi consensus in early onset FGR. Now you take an example where the smallness is detected beyond 32 weeks. So that is the late onset again the criteria remains the same for smallness. Again the criteria remains the same for absolute smallness or a severe smallness when it is less than 3rd centile you are definitely going to call it as FGR even though everything else is normal. Even though your Doppler is normal if it is less than 3rd centile it is going to be an FGR baby. So it is a solitary parameter to diagnose FGR. Now if you see that though it was small the AC or AFW is between 3rd and 10th centile. So now you are going to need a contributory parameters to diagnose FGR and what are these contributory parameters 2 out of 3 of the following which are these three AC AFW less than 10th centile of course you know because this is needed to define your smallness and which are the other is the AC AFW crossing centiles what we understood this concept before the crossing centiles or a falling growth velocity. If they fall more than 2 quartiles what is a quartile it is 25 percentile. So if it falls to more than 50th centile then also we will consider this as one of the finding one of the parameter to diagnose the FGR and what are the Doppler parameters CPR less than 5th centile or umbilical artery PIM more than 95th centile. So two of these criteria will tell you if it is the FGR and not his GA baby. So it may be that the Doppler parameter may be abnormal and the crossing centile is detected then also you will call it as the FGR fetus. So if it is there then FGR baby and if it is not there then it is a small for gestational age baby. So these are just to summarize the criteria proposed by an international Delphi consensus to detect the late onset FGR. So this is the absolute parameter or the solitary parameter severe smallness or at least 2 out of 3 of these following criteria which are the contributory parameters. We will just see it with the help of examples so that you understand it better. Now you see the scan at 36 weeks the AC is at 6th centile, AFW is at 8th centile. So smallness is detected it is late onset. Now you have to differentiate it between SGA versus FGR. Is it severely small to say directly that this is FGR no it is not below 3rd centile. So I need the help of contributory parameters and what are these these are the Doppler parameters. What are my Doppler parameters? The umbilical artery Doppler is PI is 1.5 which is 95th centile and more CPR is normal at 12 centile. But I have one parameter which is smallness that AC 6 centile and I have the criteria of umbilical artery Doppler abnormal so I will call it as the FGR fetus. Now if you take this example where it is not very small to call it directly as FGR. So we have done the Doppler and the umbilical artery Doppler is PI 80th centile and CPR is 18th centile both of them are normal. So only one parameter what I have is the smallness less than 10th centile. You do not count AC and AFW you have to call them together as one parameter that is biometry being abnormal. So now with this I call this as a small for gestational age and not the FGR baby because I have only one contributory factor and I do not have two contributory factors to call it as a FGR fetus and of course you should have seen the growth velocity that these centiles have not fallen below two quartiles more than two quartiles. So then I will call it as HGA versus FGR so that needs to be considered. Now if you see this fetus whose AC is 1.7 centile and AFW is at 6 centile umbilical artery Doppler is normal CPR of course also was normal so will it be FGR or SGA it will be straight way FGR irrespective of my Doppler parameters because the AC is at 1.7 centile which is less than third centile and it is a severe smallness. So this is an absolute or solitary criteria which can diagnose FGR. So just to summarize we should remember that all SGA fetuses are not FGR so you need to differentiate between the two but mind you all FGR fetuses may not be small. The weight may be 12 centile but if it is crossed more than two quartiles it is going to be the FGR fetus so that needs to be remembered and that's why the growth velocity and crossing centiles are important especially in the late onset FGR and the correct interpretation of biometry and Doppler helps to differentiate FGR subset from the SGA babies. After this we will then see the staging and management protocols in FGR babies in our next video. Thank you.