Uterine size or Small for Date:
You can know for sure whether SFD FETUS OR NOT , if you have previous US readings taken earlier, to compare. US Readings of earliest weeks measuring CROWN RUMP LENGTH, IS THE MOST ACCURATE & RELIABLE TO CALCULATE FOR THE GESATTIONAL AGE FETAL AGE.
There is no such criteria like UTERINE SIZE DISCRIPENCY FOR fetal age calculation by US.
The fundal height is only a subjective finding. It is not a reliable indicator after 32weeks of pregnancy, by palpation, though not during 23weeks of gestation.
Ultrasound findings- The gestational age of the fetal parameters are measured- like BIPARIETAL DIAMETER, FEMORAL LENTGH and the ABDOMINAL CIRCUMFERENCE AND, IF YOU NEED, THE FETAL WEGHT. With all these parameters the THE FEATL AGE/ the gestaional age IS CALCULATED IN THE US ITSELF AND DISPLAYED ( for takin g a graph also.)
The fetal parameters at this age (as a matter of fact, very early age of the fetus) is the authenticated and reliable (for matters of days variation in age) one for gestational/fetal age.
Either of these can be derived- 1)whether Small for Date2) or the fetal age/age of gestation itself is only that much meaning the LMP was wrong or unknown or not reliable. The gestational age as per LMP calculation is the orbitary in certain cases.. If you have previous US readings, taken before, say about 12weeks,16weeks 20weeks( even the earliest one like at 6-10weeks with the CROWNRUMP LENGTH OF THE FETUS) ARE VERY VERY RELIABLE, TO COMPARE AND SAY WHETHER IT CORRESPONDS TO AND APPROPRIATE FOR DATE/ OR SMALL FOR DATE AT THIS TIME OF EXAMINATION.
It does not matter what the uterine size is, as regards to evaluate small for date or not, when you have US findings with you ; uterine size can be falliable,. you know, many conditions can go against the specificity/validity to of the gesational age calculation.
By the way, the US reading does not give you the gestational/Fetal age, in terms of the uterine size . It does not measure the SIZE OF THE UTERUS, though it can detect abnormalities of the uterus in pregnancy too, if you are keen in looking for it. No Physician is going for US findings of UTERINE SIZE for gestational calculation.
So in brief, compare with previous US readings. If not available, this US reading of the fetal age can be taken for granted (at this age) for calculation and go for fetal growth parameters thence.
However, the measurements for SFDate fetus calculation usually and reliably starts from around 22weeks.
Please go for the previous US readings or keep watching from now on.
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