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Coder's Guide to ASC and Physician Practice Modifiers

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Modifiers (usually 2-digits) are added to the main procedure code to signify that the procedure has been altered by a distinct factor. Modifiers are accepted by most payors. Modifiers can increase or decrease reimbursement. They can also cause claims not to pay properly or deny if used incorrectly or not used, when necessary. Some modifiers are for use by ASCs only, some for physician practices and some are for use by both provider types. Correct modifier usage is under close review by Medicare at the present time.

Note: The ASC’s “global period” or “postoperative period” is 24 hours from the time the surgery begins. It is not 10 or 90 days as it is for physicians. Some payors may consider the global period to be 48-72 hours for ASCs.

Here is a guide to the modifiers used by ASCs and physician practices. The letter ‘A’ will be placed next to the modifier description, in parentheses, for those modifiers used by ASCs; the letter ‘P’ will designate those modifiers used by physician practices. ‘A&P’ will designate modifiers used by both types of providers.

-50 — Bilateral procedures (A&P)  
Use this modifier when an identical procedure is performed on both the right and left sides of the body. The policies each payor follows for the use of modifiers for reporting bilateral procedures can vary widely, so the ASC facility should check with each payor to which they submit claims for their preferred method of billing bilateral procedures. Modifier -50 identifies a procedure performed identically on the opposite side of the body (mirror image). Some payors prefer the use of the -50 modifier, and others require the use of the -RT anatomic modifier on one code and the -LT modifier on the other code. Don’t mix the use of -50 and -RT or -LT modifiers on the same code. Many payors will reduce the second procedure by one-half when using the -50 modifier. Don’t use bilateral modifiers on those CPT codes with descriptions designated as “bilateral” or “unilateral or bilateral”.

-51 — Multiple procedures
ASCs should not use the -51 modifier on their codes, unless the payor requires its use. When more than one procedure (excluding E&M codes) is performed on the same day during the same encounter by the same physician, modifier -51 should be appended to the subsequent procedures on the physician’s claim. The exception to this guideline is if the CPT code is an add-on code, or if it is –51 modifier-exempt.

-52 — Reduced services (A&P)
This modifier is used to indicate that a procedure was partially reduced or eliminated at the physician’s discretion. Usually, the procedure fee is reduced to reflect the reduced services provided.

-58 — Staged or related procedure or service by the same physician during the postoperative period (A&P)                               
Use this modifier to indicate the performance of a procedure or service during the post-operative period that was:

  1. Staged;
  2. More extensive than the original procedure; or
  3. For therapy following a diagnostic surgical procedure.

-59 — Distinct procedural service (A&P)                       
Use this modifier to indicate the procedure or service was distinct or independent from other services performed on the same day, to identify procedures not normally reported together (due to CCI edits or “separate procedure” status in the CPT book), but which are appropriate under the circumstances or to represent a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion or separate injury not normally encountered or performed on the same day by the same surgeon.

This modifier may override edits in the payor’s system, which would normally deny the code (i.e., unbundling, etc.), but under special circumstances, the modifier can be used to make the service payable — thus, the -59 modifier has a higher audit potential with Medicare and other payors.

Note: Do not use a -59 modifier on the first code listed on the claim form. Claims filed with this modifier may be under close review by Medicare. Do not use this modifier unless it is absolutely necessary (such as a situation where CPT codes are unbundled and will be denied without use of the -59 modifier). Do not use the -59 modifier like the -51 modifier to merely to indicate an additional procedure was performed.

-73 — Discontinued outpatient hospital/ASC procedure prior to the administration of anesthesia (A)                       
This modifier is appended to the CPT code for the intended procedure(s) to indicate that a procedure was terminated due to medical complications after the patient had been prepared for surgery and taken to the OR, but before anesthesia was induced. The ASC must have “expended significant resources” to charge for the scheduled procedures using this modifier, and the patient must be physically located in the OR or the procedure room where the procedure was to be performed in order to bill Medicare — the pre-op area is not allowed.

-74 — Discontinued outpatient hospital/ASC procedure after the administration of anesthesia (A)                   
This modifier is appended to the CPT code for the intended procedure(s) to indicate that a procedure was terminated due to medical complications after anesthesia for the procedure was induced.

-76 — Repeat procedure or service by same physician (A&P)               
Use this modifier only if an identical procedure is being performed following the initial procedure. The time frame for this usually falls during the usual physician’s global period for the surgery.

-77 — Repeat procedure or service by another physician (A&P)           
This modifier is used in the situation where a physician repeats a procedure that had previously been performed by another physician. It is usually assumed to occur on the same day that the initial procedure was performed.

-78 — Return to the OR for a related procedure during the postoperative period (A&P)
This modifier will result in reduced reimbursement for the physician as the payment will reflect the surgery component only. However, failure to use this modifier, when necessary, will probably result in a claim denial. An example of the correct use of this modifier would be when a patient has a postoperative bleed and has to be taken back to the OR for a control of bleeding procedure.

-79 —Unrelated procedure or service by the same physician during the post-operative period (A&P)
This modifier is to be used to indicate that an unrelated procedure was performed by the same physician during the postoperative period. It is best to usually use modifier -78 for this situation, as it reimburses at a higher rate. This modifier is meant for situations where a patient presents (during the postoperative period) for a problem requiring a service or procedure that is not related to the surgery that was previously performed.

-RT — Right side; -LT (Left side) (A&P)                       
It is extremely important to use the -RT and -LT anatomic modifiers on eye procedures and for podiatric procedures. Many orthopedic procedures require the use of these modifiers as well. Not using them when they are necessary can have a profound effect on reimbursement. If you bill a procedure that will be done bilaterally without the modifier for that side, when you bill the other side later, it may (needlessly) be denied as a duplicate claim, which will have to be appealed. Do no use these modifiers on skin codes from the 10000 section, except for breast procedures.

Note: It is extremely important to append the appropriate -RT and -LT anatomic modifiers to CPT codes on claims, when needed (e.g., orthopedic services). When a patient has a bilateral problem (such as bunions on both feet), the surgeries to correct the problem may be done one side at a time, with the patient returning months later for the repeat procedure on the other side. If the claim for the first surgery is submitted without the appropriate -LT or -RT modifier, oftentimes when the payor (or Medicare) receives the claim for the second surgery, they will deny it as a duplicate claim. It saves a great deal of time, energy and money to append the appropriate modifier on the claim the first time through and thus avoid these types of unnecessary denials.

-TC — Technical component (A&P)
The –TC modifier reflects that the technical component only of an X-ray is being billed for by the ASC. This is billing for the taking of the X-ray or use of fluoroscopy by the facility.

Digit Modifiers (A&P)                                   

Left hand

-FA Left hand, thumb           
-F1 Left hand, second digit       
-F2 Left hand, third digit           
-F3 Left hand, fourth digit           
-F4 Left hand, fifth digit           

Right hand
-F5 Right hand, thumb
-F6 Right hand, second digit
-F7 Right hand, third digit
-F8 Right hand, fourth digit
-F9 Right hand, fifth digit

Left foot
Left foot, great toe           
-T1 Left foot, second digit           
-T2 Left foot, third digit           
-T3 Left foot, fourth digit           
-T4 Left foot, fifth digit           

Right foot
-T5 Right foot, great toe
-T6 Right foot, second toe
-T7 Right foot, third digit
-T8 Right foot, fourth digit
-T9 Right foot, fifth digit

Note: Do not use –RT or –LT modifiers with these codes. Also, it is not necessary to use -59 modifier with the digit modifiers unless you need to report more than one procedure on the same toe or finger when it is separately billable.

-SG — ASC facility service (A)
For dates of service through Dec. 31, 2007, ASCs needed to use the -SG modifier on each CPT code billed on claims filed to Medicare. The changes to the Medicare program for ASCs now has Medicare requiring that, for dates of service starting Jan. 1, 2008, that ASCs are not to use the -SG modifier. This modifier may still be required by some payors on claims filed on CMS-1500 claim forms (such as Medicaid claims, if required). You should continue using –SG for payors who have previously required its use until they direct you to do otherwise. It is  not  necessary to use the -SG modifier on codes listed on claims filed on UB-04 claim forms going to other payors unless the payor requires its use. Do not use the –SG modifier on HCPCS codes billed for implants for radiology codes unless otherwise directed by the payor.

-GA — Waiver of liability on file (A&P)
While ASCs used to use the -GA modifier in the past to indicate to Medicare that a patient was having a procedure not covered in an ASC, ASCs should not be using this Modifier any longer. CMS changed the rules in 2001 preventing ASCs from pursuing ABNs for non-covered procedures performed in the ASC setting when that procedure is covered by Medicare in another setting, such as the hospital.

-GY — Statutorily excluded (A&P)
If your facility is trying to bill all payors with the same codes in the same manner — since some payors other than Medicare may get mad if you bill them for something you don’t bill to Medicare — it can be challenging since some payors (especially Medicare) do not cover all billed codes for procedures performed. When billing a CPT code to a payor you know is not covered by that payor (for example, billing 77003 (fluoroscopy) to Medicare), append the -GY modifier. This lets the payor know you that you are aware that they don’t cover the service and you expect a denial for that charge. This code would be billed to Medicare as 77003-GY-TC.

There is verbiage change for the -GY modifier that became effective July 1, 2007. Prior to July 2007, the verbiage stated that “the –GY modifier is to be used when providers need to indicate that the item or service they are billing is statutorily non-covered or is not a Medicare benefit.” As of July 1, 2007 the verbiage states that “the –GY modifier is to be used when physicians, practitioners or suppliers who want to indicate an item or service is statutorily excluded, does not meet the definition of any Medicare benefit or mon-Medicare insurers, is not a contract benefit.”

Multiple modifiers
When using more than one modifier on a CPT code, append those modifiers which affect payment (i.e., modifiers -GY, -59, -73, -74, -50, -52, etc.) before those modifiers which are informative in nature only (i.e., -LT, -T3, -78, -TC, etc.). For Medicare facility claims, the -SG Modifier is always placed first on the CPT codes, and followed by other modifiers. If you run out of space for all necessary modifiers in the usual field on the claim form, append the first or second essential modifier, followed by the -99 multiple modifiers modifier, and then continue the other modifiers in the other modifier field (field 19 on a CMS-1500) on the claim form.

Note: CPT codes are copyright by the American Medical Association.

--Stephanie Ellis, RN, CPC, is president of Ellis Medical Consulting. Learn more about Ellis Medical Consulting by visiting

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