General Surgery Coding Alert

Nugget: Optimize payment for fistula complications by correctly identifying the type of repair, documenting the procedure completely and paying attention to global periods when choosing the right billing method.

An arteriovenous (AV) fistula a surgically created connection between an artery and vein that provides future sites for hemodialysis access typically is created in a patient with renal failure for the purpose of dialysis. Thrombectomies performed during the global period of the creation of an AV fistula are not bundled, but to obtain reimbursement, the correct diagnosis code and modifier must be used, coding experts say.

The fistula creates a large blood supply to a venous system, and huge veins form on the arm, allowing easy access for dialysis, says M. Trayser Dunaway, MD, a general surgeon in Camden, S.C. The creation of the fistula itself also can be confusing because it is accompanied by the insertion of temporary devices that are used while the fistula matures.

The fistulas may take several weeks to mature, however, so catheters are implanted to allow dialysis to begin right away. Before and after the fistula matures for dialysis use, problems may occur, Dunaway says. Sometimes the connection between the artery and the vein clots off. Then you have to remove the clot to restore the patency of the vessel at the anastomosis. Sometime later, it could even be in the recovery room, the AV fistulas thrill (blood flow) is lost, so the surgeon has to fix the problem.

When to Perform a Repair

Two main procedures may be performed in these situations: thrombectomy (removal of a clot); or revision of the fistula, which occurs if the surgeon goes back in and takes the anastomosis apart and then puts it back together.

One or both of these procedures often are performed several times in the same week, depending on the patient, says Kathleen Mueller, RN, CPC, CCS-P, a general surgery coding and reimbursement specialist in Lenzburg, Ill.

A typical scenario follows: A male, 52, with renal failure is taken to surgery for AV fistula formation for dialysis. The surgeon creates the fistula using grafted tissue from the patient and also inserts two Tesio catheters that are tunneled under the skin so dialysis can begin immediately. Two days later, the patients thrill is gone because the fistula has clotted off. The surgeon goes back in, performs a thrombectomy and reconstructs the anastomosis.

Creation of AV Fistulas

The original procedure is coded as follows:

36825 creation of arteriovenous fistula by other
than direct arteriovenous anastomosis [separate
procedure]; autogenous graft

36533 insertion of implantable venous access
device, with or without subcutaneous reservoir

36533-59 distinct procedural service

CPT contains two codes for the creation of an AV fistula: 36825 and 36830 (nonautogenous graft). In this case, an autogenous graft was performed, because the fistula was created from tissue taken from the patients own body; 36830 should be used if synthetic (non-autogenous) materials are used.

Note: Some surgeons perform a newer procedure that purports to decrease subsequent clotting and revisions. This procedure is 36819 (arteriovenous anastomosis, open; by basilic vein transposition).

The other procedure performed, the insertion of a venous access device, is not bundled into the 36825 and is separately payable. There are, however, two different kinds of venous implantation 36533 and 36488-36491 (36488, placement of central venous catheter [subclavian, jugular, or other vein] [e.g., for central venous pressure, hyperalimentation, hemodialysis, or chemotherapy]; percutaneous, under age 2; 36489, over age 2; 36490, cutdown, under age 2; 36491, cutdown, over age 2).

The 36488-36491 codes typically are used for short-term IV access. A catheter is implanted percutaneously or by cutdown into the subclavian or internal jugular. For longer-term use, code 36533 is used. This procedure involves making at least one incision, and the catheter is inserted and tunneled under the skin through subcutaneous tissue into the vein. In this case, because the central line was tunneled under the skin, 36533 is the appropriate code.

When coding the insertion of the catheters for venous line access, the important thing is not the brand name of the catheter but how the catheter actually was inserted into the body, Mueller says. The key word to look for to distinguish between the two procedures is tunneling. If the procedure includes tunneling, bill code 36533; if not, bill code 36489.

Another code, 36800 (insertion of cannula for hemodialysis, other purpose [separate procedure]; vein to vein), is used to describe an older type of dialysis performed with a shunt and would not be appropriate in most situations.

Note: For a detailed discussion about the insertion of vascular catheters for venous access, see General Surgery Coding Alert, More Than Name Needed to Correctly Code for Insertion of Vascular Catheter for Venous Access, Vol. 1, No. 3 (September 1999), page 17.

The diagnosis code for the formation of the AV fistula could be 585 (chronic renal failure), but it also could be based on the actual condition itself (e.g., diabetes with renal manifestations, hypertensive renal disease, hypertensive heart and renal disease, and glomerulonephrosis). These diagnoses also may be used for the catheter insertions, as can diagnosis code 459.89 (other specified disorders of circulatory system; collateral circulation [venous], any site; phlebosclerosis; venofibrosis).

Correctly Coding a Repair

In the example above, the revision and thrombectomy performed after the initial creation of the fistula is coded 36833 (revision, arteriovenous fistula; with thrombectomy, autogenous or nonautogenous dialysis graft [separate procedure]). If revision without thrombectomy was required, 36832 (revision, arteriovenous fistula; without thrombectomy; autogenous or nonautogenous dialysis graft [separate procedure]) would be the correct code. If thrombectomy alone was performed, code 36831 (thrombectomy, arteriovenous fistula without revision, autogenous or nonoautogenous dialysis graft [separate procedure]) should be used.

These three codes were added to the CPT manual in 1999; before that, codes used for fistula revision/ thrombectomy included 35875 (thrombectomy of arterial or venous graft [other than hemodialysis graft or fistula]); 34490 (thrombectomy, direct or with catheter; axillary and subclavian vein, by arm incision) for veins and 34101 (embolectomy or thrombectomy, with or without catheter; axillary, brachial, innominate, subclavian artery, by arm incision). Since the introduction of the new codes, these procedures can no longer be billed this way. These codes, today, are likely to be denied when used for fistula revision/thrombectomy, Mueller says.

Choosing the Correct Diagnosis Code and Modifier

Two key elements in getting these claims paid are that the correct diagnosis code and modifier must be used. Although the patients renal failure is indirectly responsible for all the symptoms, the immediate cause of the thrombectomy and/or revision is a mechanical complication (i.e., clotting off of the fistula). Therefore, the primary diagnosis code for the revision/thrombectomy would be 996.1 (mechanical complication of other vascular device, implant, and graft), which includes fistulas, Mueller says.

If the revision/thrombectomy occurs within 90 days of the creation of the fistula, it falls within that procedures global period, so modifier -79 (unrelated procedure or service by the same physician during the postoperative period) should be attached to the 36833. Revisions and de-clotting are not part of 36825s global package and may be billed separately.

Note: CPT 36831, 36832 and 36833 have 90-day global periods; however, each revision is separately billable, and even if several are performed within a week, a new 90-day global period begins after each service is performed.

Although many coders use modifier -78 (return to the operating room for a related procedure during the postoperative period) because they believe the repair is related to the fistula creation, modifier -79 is more appropriate, Mueller says. The fistula repair is related to the underlying illness but not to the creation of the fistula, says Mueller. It is not a complication. Modifier -78, she notes, should be attached to Medicare claims mainly to report complications.

Because payers may have different policies, general surgeons should check if their local carriers consider the repair a complication of the original procedure before billing for it, Mueller adds.

Note: Sometimes patients require a patch angioplasty while a revision/thrombectomy is being performed to identify the area where the clot is; these, however, are included in 36831-36833.

Elaine Elliott, a practice coder with Treasure Coast Surgical Associates, a general surgery practice in Stuart Fla., contributed to this article.