EPV can be measured from 7 to 40 weeks. Use widest angle probe for large placentas. Beyond 36 weeks the placenta may be too large to visualize the entire width.
Ideal measurements: Freeze a perpendicular cross section at the maximal width of placenta. Take Width measurements from edge to edge. Start at apex and measure Height and Thickness down to baseline along same line (at right angles to Width line). Height is always greater or equal to thickness.
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Placenta is an obvious crescent. Baseline Width is measured from tip to tip (+), yellow line.
Apex is found and Height is measured from apex to baseline (⸭), yellow line perpendicular to Width line.
Thickness is measured starting from same apex point as Height and then measured along the same line down to edge of placenta (✕), orange line.
Placenta is flat, without any evidence of curvature. The maximal Width is measured from tip to tip (yellow). The Height and Thickness (orange) are the same and are measured once to obtain both values.
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