Flashcards in Fetal Age & Measurements Deck (64)
Sonographic measurements of the fetus provide info about...
1. fetal age
3. diagnose growth disturbances
This is the true measure of age, the number of days since conception.
This is the number of days since the first day of the last menstrual period.
Accurate knowledge of gestational age is important...
Telling normal from abnormal and timing of ...
3. elective induction
Dating by LMP may be inaccurate because of...
1. variability of cycle length
2. faulty memory
3. oral contraceptives
4. bleeding during early pregnancy
Determining gestational age from fundal height may be affected by...
1. uterine fibroids
2. multiple pregnancy
3. maternal body habitus
From 5-6 weeks, there are two methods for assigning gestational age. They are?
2. contents of the sac
This is the average internal diamter of the sac.
The sac is _mm at 5 weeks and _mm at 6 weeks.
You should only use the MSD for dating if..
you don't see an embyro.
If the difference between the MSD and the CRL is 5 mm or less there's a high risk of...
The heartbeat should always be seen from __ weeks onward.
The term 'embryo' applies until the __ week.
CRL correlates closely with GA until around the __ week.
What are the main measurements in the 2nd and 3rd trimesters?
If the AC is too short, look for signs of...
If the FL is too short, look for signs of...
What are the three head measurements?
BPD measures from the ___ edge of the near side of the cranium to the ___ edge of the far side of the cranium.
What anatomic landmarks do you need to measure the BPD?
1. symmetrically postioned thalami
2. cavum septum pellucidum
Sonographically, this refers to the relationship between the fetal cranial sagittal suture and the central portion of the u/s beam.
angle of asynclitism
For an exact BPD, the angle of asynclitism should be...
90 degrees to the cranial sag suture
This is the length of the outer perimeter of the cranium, made at the same level as the BPD.
T/F? HC should include scalp echoes when using the ellipse method.
FALSE, should not
This is the measure of the long axis of the fetal head, at the same level as the BPD.
The OFP should be measured from the ___ edge to the ___ edge.
In this condition, the AP length of the fetal head is shortened.
In this condition, the AP length of the fetal head is lengthened.
This is obtained by measuring the widest and longest dimension of the fetal skull.
cephalic index (CI)