My doc was called out of our office STAT to perform an echo (93303, 93320, 93325) on a newborn in the NICU. The newborn was put on nitric oxide for pulmonary hypertension. Doc went back to the hospital after clinic and performed another echo (93304, 93321, 93325) to verify that the treatment was working. How is this coded? Does the follow up 93304 need a 76 modifier? And the add on code 93325 show 2 units?