Ask Dr. Z

"Patient has a scab over the AV fistula, and the physician is concerned the patient might start bleeding. An eliptical incision was made over the area of the scab and carried down through the skin and subcutaneous layers. The scab was lifted off the fistula; the underlying fistula, however, was intact and did not need any intervention. He then simply freshened up the edges of the fistula. He went ahead and undermined both the medial and lateral flaps of skin and then began closing the wound using layers. Deep layer was closed using 3-0 vicryl; skin was closed using a 4-0 monocryl." I'm not sure of the proceudure and diagnosis coding. In his pre- and post-op dx, the physician mentioned arteriovenous fistula malfunction. I'm not sure if this is considered a fistula malfunction. Please advise.