When do you categorize the office visit E/M high risk?

Ex: A patient comes in for her normal OB visit, but complains about abdominal paid. Physician does an ultrasound. As we know we code the ultrasound and bill the ultrasound.

Now how about the office visit E/M, are you coding the same for the office visit (abdmoninal pain) or are you not coding an office visit since this was origianlly a normal OB E/M visit and only billing the ultrasound.

Does the office visit have to have a difference diagnosis coded?

Any input would be great thank you!!