LMP should be the date that the bleeding started. Not the date that the bleeding stopped.
EDD = only 5 % of women deliver in their EDD
30 days in november, april, june, spet
All the rest has 31 except feb
Only if regular 28 days cycle
If more than that or less than that must add or subtract the extra days.
Ovlation occurs 14 days before the LMP, so add or subtract the days
but if cycles are irregular then cant calclate edd this way. mst se ultrasound
the more earlier the dating was done the more accurate it is. because later on in pregnancy other aspects affects the growth. Before they effect must measure. early on in pregnacy most fetusses grow at the same pace so calcuations can be sed to estimate the gestation age. later on growths vary. so need to do dating scan early and then later on use this dating scan to check for iugr or not etcu
CRL = is the best measurement for datin. the best time for dating is the first trimester and so
limb isnt considered as as rump
means POG is accurate within 5 to 7 days. In this case the 10 wks
SO USE THIS TO CHECK WHETHER THE EDD IS CONSISTENT WITH HER LMP. UL DATES CONSISTENT WITH THE CALCULATION.
Abdomen becomes jst palpable at 14 weeks
CRL is only accurate to 13 weeks 6 days
1st trimester until 13 weeks 6 days = CRL is est
2nd trimester ⇒ BPD
3rd trimester ⇒ FEMUR LENGHT IS BEST
But in 2nd trimester, must use a composite dating method to date using all, but if asked in exams BPD is best.
must assess from diaphysis not epiphysis
Must measure the abdominal circumference in a frame that has the stomach bubble, the j shape area where the porto and umbilical vein meet and the aorta.
2,3 weeks variations.
Femur length is the best in T3 but composite is better !
So if come in 2nd trimester or later can rely on 1. dating scan ultrasound dates 2. per abdominal exam now 3. ultrasond exam now 4. LMP CALCULATIOn but 1 supercedes all!
To check whether 1 is corresponding must calculate POG again using 1 (dating scan stuff) and then check whether this is consistent with 2 and 3.
Always prioritise the dates given in 1 = as earlier the better.
And for every visit will have to use what this dating scan told yo.u.
variation of dating calculations using ultrasound of last trimester is 2-3 weeks!
even though you technically have to correct dates only if 5 day discrepency before certain times and 7 days after that, usually POG calclated suing LMP isnt taken at all becase reglar or not? can remmeber lmp correctly or not?
for ivf is the time since ET + 2 weeks.
hand held doppler can ascertain fetal heart sound from 10 weeks.
Urine test turns positive after 4 weeks
Ultra-sound scanning in pregnancy
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