Ob-Gyn Coding Alert

Question: How should I bill for the service of fern testing when the doctor is looking for amniotic fluid in the vaginal secretions of a pregnant woman?

Wisconsin Subscriber

Answer: Fern testing is done to check for ruptured membranes. It involves putting a drop of fluid from the vagina onto a slide, letting it dry and then examining it under a microscope to see if there is a fern-like pattern. The fern-like pattern will be present if the fluid is amniotic fluid because it is saline in nature. If this is the procedure your physician has performed, the closest code is 87210 (smear, primary source, with interpretation; wet mount with simple stain, for bacteria, fungi, ova, and/or parasites). If a fern test is done using a Nitrazine dipstick, on the other hand, it should not be coded separately from the office visit because this does not involve significant physician work.