OB ultrasound - V28.81 versus V28.3 (see HBM April 2015)

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In the new Healthcare Business Monthly, there is an article on OB ultrasounds 76805 and 76811.

I am a little confused regarding the diagnosis codes V28.3 and V28.81. We have been utilizing V28.81 when patients present for an antenatal ultrasound for dates and anatomy. Our physicians order these at 20 weeks routinely. This article states the correct diagnosis code is V28.3, Encounter for routine screening for malformation using ultrasonics. The definition for V28.3 actually does exclude the use of V28.81, Encounter for fetal anatomic survey, which is what we are using.

My question is what is the difference between encounter for "malformation" determination (V28.3, the correct code given above) and encounter for "fetal anatomic survey" (V28.81, the code we have been utilizing)?

I should mention that our ultrasounds are NOT done in the clinic setting and are being done in the hospital outpatient setting.