Modifiers

Proper Use of Modifiers 59 and 91

Table of Contents

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Modifier 59

Claim submissions and redeterminations received by National Government Services indicates a large volume of claims denying for incorrect usage of modifier 59.

Modifier 59 is defined as a “distinct procedural service.” Under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-E/M services performed on the same day. Modifier 59 is used to identify procedures or services, other than E/M services, that are not normally reported together, but are appropriate under the circumstances. Documentation must support a different session, different procedure or surgery, different site or organ system, separate incision or excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same physician. However, when another already established modifier is appropriate, it should be used rather than modifier 59. Only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used.

Note: Modifier 59 should not be appended to an E/M service performed on the same date, see Modifier 25.

Medicare considers two physicians in the same group with the same specialty performing services on the same day as the same physician.

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Appropriate Usage

  • Represented by a different session or patient encounter, different procedure or surgery, different anatomical site, or separate injury or area of injury
  • Medical record documentation indicates two separate distinct procedures performed on the same day by the same physician
  • May be used on either the Column 1 or Column 2 code listed in NCCI edits
  • Only when there is no other appropriate modifier to use

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Inappropriate Usage

  • Code combination does not appear in the NCCI edits
  • Not be appended to an E/M service performed on the same date, see modifier 25
  • MPFSDB lists the procedure code with a modifier indicator of "0"
  • The medical record documentation does not support the separate and distinct status
  • The exact same procedure code was performed twice on the same day (see Repeat Procedures - Modifiers 76 and 77)
  • If a valid more appropriate modifier exists to identify the services

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Modifier 91

Modifier 91 is used to indicate a repeat laboratory procedural service on the same day to obtain subsequent reportable test values. The physician may need to indicate that a lab procedure or service was distinct or separate from other lab services performed on the same day. This may indicate that a repeat clinical diagnostic laboratory test was distinct or separate from a lab panel or other lab services performed on the same day, and was performed to obtain subsequent reportable test values.

Multiple laboratory services provided to a patient on one day by the same provider may appear to be incorrectly coded, when in fact the services may have been performed as reported. Because these circumstances cannot be easily identified, modifier 91 was established to permit claims of such a nature to bypass correct coding edits. The addition of this modifier to a laboratory procedure code indicates a repeat test or procedure on the same day.

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Appropriate Usage

  • Identify a subsequent medically necessary laboratory test on the same day of the same previous laboratory test

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Inappropriate Usage

  • Due to testing problems for the specimen or testing problems of the equipment
  • Rerun of a laboratory test to confirm results
  • When the procedure code describes a series of test

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Additional Information

  • Modifier 91 does not replace modifiers such as RT, LT, 50, E1-E4, FA, F1-F9, TA, and T1-T9.
  • If billing a procedure code two or more times for the same date of service, the claim should be submitted with the procedure code listed on one line without modifier 91 and each subsequent procedure listed on a separate line using the modifier 91.

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Revised 10/16/2024