Appropriate Use of Modifiers XE, XP, XS, XU, or 59

Modifier 59 is the most widely used HCPCS modifier. This modifier is associated with considerable misuse and high levels of manual audit activity, leading to reviews, appeals, and even civil fraud and abuse cases. The introduction of four ‘X’ subset modifiers is designed to reduce the improper use of modifier 59 and help to improve and speed up claims processing for providers.

Modifier 59 and other NCCI-associated modifiers should NOT be used to bypass an NCCI edit unless the proper criteria for use of the modifier are met. Documentation in the medical record must satisfy the criteria required by any NCCI-associated modifier used. From an NCCI perspective, the definition of different anatomic sites includes different organs or different lesions in the same organ. However, it does not include the treatment of contiguous structures of the same organ.

For example, treatment of the nail, nail bed, and adjacent soft tissue constitutes the treatment of a single anatomic site. Treatment of posterior segment structures in the ipsilateral eye constitutes the treatment of a single anatomic site. Arthroscopic treatment of a shoulder injury in adjoining areas of the ipsilateral shoulder constitutes the treatment of a single anatomic site.

One of the common misuses of modifier 59 is related to the portion of the definition of modifier 59 allowing its use to describe “different procedure or surgery”. The code descriptors of the two codes of a code pair edit consisting of two surgical procedures or two diagnostic procedures usually represent different procedures or surgeries. The edit indicates that the two procedures/surgeries cannot be reported together if performed at the same anatomic site and the same patient encounter.

Appropriate uses of modifier 59 include:

  • Same patient, same day, same provider
  • Different anatomic sites during the same encounter only when procedures which are not ordinarily performed or encountered on the same day are performed on different organs, or different anatomic regions, or in limited situations on different, non-contiguous lesions in different anatomic regions of the same organ.
  • When the procedures are performed in different encounters on the same day.
  • Two services described by timed codes provided during the same encounter only when they are performed sequentially.
  • The diagnostic procedure which precedes a therapeutic procedure only when the diagnostic procedure is the basis for performing the therapeutic procedure.
  • Used with the secondary, additional or lesser procedure of combinations listed in NCCI edits.
  • There is NO other appropriate modifier.

NOTE: Two physicians in the same group, with the same specialty, performing services for the same patient on the same day, are considered to be the same physician by Medicare.

Inappropriate uses of modifier 59 include:

  • When the basis for its use is that the narrative description of the two codes is different.
  • Different diagnoses are not adequate criteria for use of modifier 59
  • Code combination not appearing in the NCCI edits
  • Submission of E/M Codes
  • Submission of weekly radiation therapy management codes (CPT 77427)
  • The NCCI tables list the procedure code pair with a modifier indicator of “0”
  • Documentation does not support the separate and distinct status
  • Exact same procedure code performed twice on the same day
  • Multiple administrations of injections of the same drug
  • If a valid modifier exists to identify the services

Examples of the appropriate use of modifiers XE, XP, XS, XU, or 59:

Example Modifier

to use:

Separate surgical operative session on the same date of service (e.g.  8  AM surgery with one procedure, 4 PM surgery with second procedure code). XE Separate encounter.
Modifier XP is a little unclear.  Once possible scenario might be: The patient is seen in the office by a family practice physician, who in the course of the visit encounters a problem outside their scope of ability so calls in (or arranges an immediate transfer to) a specialist physician at the same claim to perform the needed service. XP
  • Maybe the same encounter.
  • Is definitely the same clinic/TIN.
  • Different provider specialties apply.
  • E/M service may normally be included in the therapeutic treatment or minor surgical procedure.
Injection into the tendon sheath, right ankle (20550), and injection into the tendon sheath left ankle (20550- XS). XS
  • Same encounter
  • The different anatomical sites and contralateral structure.
  • (Note: 20550 is not eligible for modifiers LT or RT.)


Separate injury (or area of injury in extensive injuries). XS versus 59 Depending upon your specific circumstances XS or 59 may be most appropriate.
A right cardiac cauterization (93451) was performed. Based on the findings, a medically necessary cardiac value repair (33418) was required.
The NCCI edits reveal a “1” indicator. What modifier should be reported on the code combination? What is the proper billing?
XU Depending upon your specific circumstances XU or 59 may be most appropriate.
A diagnostic procedure is performed. Due to the findings, a decision is then made to perform a therapeutic/surgical procedure. (This may or may not occur in the same procedure room during the same session/encounter.) For example, diagnostic cardiac angiography leads to therapeutic angioplasty.
See CCI Policy Manual, chapter 1, modifier 59 guidelines. (CMS 2)
XU versus 59 Depending upon your specific circumstances XU or 59 may be most appropriate.
Benign skin lesion (0.7 cm) removed from left posterior ribs (11401) and benign skin lesion  (0.4  cm) removed from the right arm (11400-59). 59
  • Same encounter
  • Same organ system and/or structure (skin)
  • Different lesions.
Diagnostic mediastinoscopy via midline incision (39400) and thoracoscopy of the right lateral lung via lateral incision with biopsy of pleura (32609-XS??).
Different organ systems (e.g. laparoscopy on separate organ systems).
  • Same encounter
  • Same organ system (respiratory)
  • Different incision.


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