Common Measurement Techniques in OB/GYN
Sonography (Correctly solved)
abdominal circumference (AC) correct answers ellipse around abdomen (including subcutaneous
fat and skin)
biparietal diameter (BPD) correct answers outer skull to inner skull (leading edge to leading
edge)
cephalic index (CI) correct answers BPD/OFD
cerebellum correct answers lateral edge to lateral edge (transverse)
cervical length correct answers internal os to external os where anterior and posterior cervical
walls touch
cisterna magna correct answers posterior cerebellum to inner occipital bone AP
crown rump length (CRL) correct answers crown to rump of embryo
endometrium correct answers outer basalis to outer basalis; AP measurement in sagittal scanning
plane
endometrium with fluid in cavity correct answers measure anterior and posterior endometrial
tissue and add together
femur length (FL) correct answers edge to edge of ossified diaphysis (midpoint of slant distally
third trimester)
gestational sac (GS) correct answers inner to inner
head circumference (HC) correct answers ellipse around outer skull margin (no skin/scalp
included)
humerus (HL) correct answers end to end
lateral ventricular atrial width (LVAW) correct answers inner to inner at the level of the glomus
of the choroid plexus
nasal bone (NB) correct answers edge to edge on midsagittal view (transducer 45 degrees to fetal
profile)
nuchal fold (NF) correct answers outer occipital bone to outer skin
nuchal translucency (NT) correct answers inner edge to inner edge ("on to on")
Sonography (Correctly solved)
abdominal circumference (AC) correct answers ellipse around abdomen (including subcutaneous
fat and skin)
biparietal diameter (BPD) correct answers outer skull to inner skull (leading edge to leading
edge)
cephalic index (CI) correct answers BPD/OFD
cerebellum correct answers lateral edge to lateral edge (transverse)
cervical length correct answers internal os to external os where anterior and posterior cervical
walls touch
cisterna magna correct answers posterior cerebellum to inner occipital bone AP
crown rump length (CRL) correct answers crown to rump of embryo
endometrium correct answers outer basalis to outer basalis; AP measurement in sagittal scanning
plane
endometrium with fluid in cavity correct answers measure anterior and posterior endometrial
tissue and add together
femur length (FL) correct answers edge to edge of ossified diaphysis (midpoint of slant distally
third trimester)
gestational sac (GS) correct answers inner to inner
head circumference (HC) correct answers ellipse around outer skull margin (no skin/scalp
included)
humerus (HL) correct answers end to end
lateral ventricular atrial width (LVAW) correct answers inner to inner at the level of the glomus
of the choroid plexus
nasal bone (NB) correct answers edge to edge on midsagittal view (transducer 45 degrees to fetal
profile)
nuchal fold (NF) correct answers outer occipital bone to outer skin
nuchal translucency (NT) correct answers inner edge to inner edge ("on to on")
