Obstetrical Measurements 2nd & 3rd Trimester

Obstetrical Measurements2nd & 3rd TrimesterFetal Biometry WorkshopDay 2 & Day 3Learning ObjectivesList guidelines for 2nd & 3rd trimester OB examsEvaluate fetal anatomy

Fetal "screening" may be performed as either part of a basic exam ("level 1") or a detailed scan ("level 2" or higher). A basic or level 1 scan does not need to make a specific diagnosis but should be able to tell when something is wrong, resulting in a referral for a detailed or "level 2" scan. Both the "screen" and the "diagnosis" can even take place at the time of a single ultrasound.2Protocol 2nd & 3rd TrimesterCervixFetal LieSitusAFIPlacentaCordFacial ProfileNose & LipsBPD & HCCerebellumCisterna MagnaChoroidsLateral VentricleDiaphragmACBladderKidneysFetal Heart4 chamberLV & RV outflow3 Vessel viewFemur lengthExtremitiesPhalangesGenderSpine

One of the most important technical considerations in developing scanning expertise is to become organized and systematic in assessing the fetus, placenta, and amniotic fluid3CervixAvoid measuring the cervix with a LUS contraction or overly distended bladder.

Need fluid in front of the internal cervical os to comment on relationship to placenta

4CervixNormal = 3-4cm

If >4 bladder is probably too fullEmpty and rescan

If < 3cmEvaluate with translabial first then transvaginalIf evaluating by TV, maternal bladder should be emptied

Watch out for curved cervix make sure you trace the curve instead of straight line

Most of the time cervix is stable from day to day

5CervixPreterm labor