CPT code 37609 – Temporal artery ligation or biopsy

Key takeaways

CPT code 37609 covers both ligation and biopsy of the temporal artery under a single unilateral code.

ICD-10-CM M31.6 (Other giant cell arteritis) is the primary diagnosis paired with 37609, with M31.5 and R68.89 as secondary options.

Surgical pathology (CPT 88305) is not bundled with 37609. The pathologist bills it separately when a biopsy specimen goes to pathology.

Medicare pays $315.64 for 37609 in the office and $188.05 in a facility in 2026, and the difference comes entirely from practice expense RVUs.

Pabau, the practice management and billing platform we build, submits 37609 claims electronically through the Claim.MD clearinghouse.

CPT code 37609: Official description and procedure variants

CPT code 37609 reports ligation or biopsy of the temporal artery, two procedures that share one code. CMS lists it in its 2026 Physician Fee Schedule relative value file as “Ligation/bx temporal artery,” with a 10-day global period. Both procedures sit under one code because they involve the same vessel and a similar level of surgical work.

The two variants are not separately reportable. Whether the surgeon performs an open excisional biopsy of a temporal artery segment or ligates the vessel to control hemorrhage, 37609 is the correct code. The procedure is unilateral by default, so each side of the head is a separate service.

• Ligation variant: The superficial temporal artery is surgically tied off, most often for scalp arteriovenous malformations or posttraumatic bleeding.
• Biopsy variant: A 1.5 to 3 cm segment of the temporal artery is excised under local anesthesia. Histopathology then confirms or excludes giant cell arteritis.
• Not separately reportable: Both variants carry the same RVU weight. Never report both on the same side in the same operative session.

How the procedure is performed

Understanding the operative steps helps coders verify that the operative note contains the documentation elements needed for a clean claim. The biopsy variant drives the overwhelming majority of 37609 volume, so this section focuses on that procedure while noting where the ligation technique differs.

1. Patient positioning and anesthesia: The patient is supine with the head turned to expose the affected temple. Local anesthetic (typically lidocaine with epinephrine) is infiltrated along the vessel course palpated anterior to the ear.
2. Incision and vessel identification: A longitudinal or slightly curved incision is made over the palpable temporal artery pulse. Blunt dissection exposes the vessel without disrupting the facial nerve branches.
3. Segment excision (biopsy) or vessel ligation: For biopsy, the surgeon excises a 1.5-3 cm arterial segment between two suture ties. For ligation, the vessel is tied without excision.
4. Specimen handling: The biopsy specimen is immediately placed in formalin and sent to pathology. The pathologist bills CPT 88305 separately for the gross and microscopic examination.
5. Wound closure: The incision is closed in layers. The procedure is typically performed in an outpatient surgery center or physician office under local anesthesia.

The operative note must state which procedure was performed (ligation or biopsy), the laterality, the anesthesia used and where the specimen went. For a biopsy, it also gives the length of the excised segment. Missing any of these elements is a common audit trigger.

Documentation requirements for CPT code 37609 claims

Payers require specific documentation to establish medical necessity and confirm the service matches the billed code. They look closely at 37609 claims, because temporal artery biopsy pays relatively well for a brief outpatient procedure.

The following elements must appear in the medical record for a defensible 37609 claim.

• Indication documented: Signs and symptoms of giant cell arteritis, such as new-onset headache, jaw claudication, visual disturbance or scalp tenderness. Any other indication for temporal artery surgery is documented too.
• Laboratory values: Elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) supporting GCA suspicion, referenced with values and collection date.
• Procedure performed: Explicit statement whether ligation or biopsy was performed, not just “temporal artery surgery.”
• Laterality stated: Right, left, or bilateral (with separate documentation for each side).
• Specimen sent to pathology: Notation that the excised segment was sent for histopathological analysis (required when billing 88305 separately).
• Surgeon attestation: The operative note is dictated or attested by the operating surgeon, not by a resident or assistant alone.

A clean claim submission for 37609 pairs these documentation elements with the correct ICD-10 code and place of service. All of it is in place before the claim leaves the practice. Once a denial is in progress, missing documentation can only be added through a formal appeal.

ICD-10-CM codes used with CPT code 37609

The ICD-10-CM diagnosis code paired with 37609 must reflect the clinical indication documented in the medical record. Giant cell arteritis (GCA) is the most common indication, and M31.6 is the standard pairing for confirmed or suspected GCA. Assigning M31.6 without supporting documentation of GCA diagnostic criteria risks claim denial and audit exposure.

The American College of Rheumatology (ACR) classification criteria for GCA inform what payers accept as clinical justification for M31.6. The 1990 ACR criteria classify a patient as having GCA when at least three of these five findings are present.

• Age 50 or older at disease onset
• New-onset localized headache
• Temporal artery tenderness or a decreased temporal artery pulse
• ESR of 50 mm/hour or higher
• An artery biopsy showing necrotizing arteritis or granulomatous inflammation

In the original study, three or more of the five findings gave 93.5% sensitivity and 91.2% specificity. Use R68.89 when the biopsy is diagnostic in intent but the GCA diagnosis has not yet been confirmed in the record.

Medicare reimbursement and RVUs for CPT 37609

Medicare reimbursement for CPT code 37609 is determined by the Medicare Physician Fee Schedule (MPFS) published annually by the Centers for Medicare and Medicaid Services. Payment rates vary by place of service and by geographic adjustment factor (GAF). The figures below are 2026 national unadjusted rates at the $33.4009 conversion factor. Verify locality-specific amounts in the CMS Physician Fee Schedule Look-Up Tool before quoting rates to providers.

Rates change each January with the annual MPFS update. Use the FastRVU lookup tool to estimate locality-adjusted payment for your area. The office rate is higher because its practice expense (PE) RVUs cover the overhead of running the procedure room. In a hospital or ASC, the facility bills that overhead on its own claim.

Work and malpractice RVUs are identical in both settings, so the whole $127.59 difference sits in practice expense, as the chart below shows.

Bilateral billing with modifier 50

Bilateral temporal artery biopsy occurs when GCA is suspected but the first biopsy returns a negative result. Because GCA can affect arteries in a skip-lesion pattern, clinicians sometimes biopsy both temporal arteries to increase diagnostic yield. Each side is a separate reportable service.

• Medicare and most commercial payers: Bill 37609 on a single claim line with modifier 50 appended (37609-50). Medicare pays the bilateral line at 150% of the unilateral rate.
• Some commercial payers and Medicare Advantage plans: They require two line items with laterality modifiers, 37609-LT and 37609-RT, each billed at 100%. Check your payer’s billing manual before submitting.
• Documentation requirement: Each side needs its own operative note entry, or a bilateral note that gives the segment length and specimen disposition for each side.
• Do not bill 37609 twice without a modifier: Two units without a modifier trigger a National Correct Coding Initiative (NCCI) edit. The second unit is then denied.

Confirm payer-specific bilateral billing rules before submission. The Medicare Claims Processing Manual covers modifier 50 in Chapter 12. Medicare Advantage plans may follow different instructions than traditional Medicare.

Prior authorization and payer requirements

Traditional Medicare does not typically require prior authorization for CPT 37609 when medical necessity is documented. Medicare Advantage plans and commercial insurers commonly do require prior auth. Requirements vary by plan, so treat the following as a general framework.

Routine insurance eligibility verification before scheduling the procedure should include a check for prior authorization requirements. Payers that require prior auth for 37609 generally demand the following clinical criteria in the authorization request.

• Patient age 50 or older (GCA is rare under 50)
• New-onset temporal headache, scalp tenderness, or jaw claudication documented in the chart
• ESR of 50 mm/hour or higher, or CRP above the laboratory’s upper reference limit, with collection date
• Ophthalmology consultation note if visual symptoms are present (the American Academy of Ophthalmology considers rapid temporal artery biopsy essential when visual involvement is suspected)
• Rheumatology consultation or primary care attestation that GCA is clinically suspected
• Failure of or contraindication to watchful waiting (some plans require a brief course of high-dose corticosteroids to have been initiated before authorizing biopsy)

When authorization is denied on initial request, appeal with ACR classification criteria evidence and a letter of medical necessity from the treating rheumatologist or ophthalmologist. Citing the published GCA criteria gives the reviewer a standard to check the chart against, which a generic necessity letter does not.

Related and commonly confused CPT codes

Several codes are misapplied when billing temporal artery procedures. The table below shows the four most common confusion points, with the clinical scenario where each code applies.

The 88305 error is the most financially significant. When the surgeon sends a biopsy specimen to pathology, the pathologist’s gross and microscopic examination is billed as CPT 88305. NCCI edits do not bundle 88305 with 37609, because different providers perform the two services. The surgeon never bills 88305. The pathology group or hospital laboratory bills it on its own claim.

Common claim denial reasons and how to avoid them

Denials for CPT 37609 cluster around four recurring problems. Each has a corrective action that can be implemented before the claim is submitted. Reactive denial management takes far longer than a documentation review before submission.

Global period and postoperative care for CPT 37609

CPT code 37609 carries a 10-day global period under the Medicare global surgical package. This means routine postoperative care services provided within 10 days of the procedure date are bundled into the 37609 payment and cannot be billed separately.

• Bundled within the 10-day global: Wound checks, suture removal, and standard follow-up for the procedure itself. Bill these at no additional charge during the global window.
• Separately billable with modifier 24: An E&M visit within the global period for an unrelated reason, such as a hypertension check. Append modifier 24 and document the unrelated reason clearly.
• Separately billable with modifier 79: An unrelated procedure performed within the global period. Append modifier 79 and document that the new procedure is unrelated to the index surgery.
• Pathology result discussion: A visit to discuss the biopsy pathology report may be separately billable as a new clinical decision. Document the complexity and bill with modifier 24 if within the global window.

Global period rules are a frequent source of audit findings on outpatient surgical procedures. The 10-day global for 37609 is short next to a major surgery’s 90 days. It still causes denials when billing teams overlook it. Check the global period each year in the CMS MPFS, because CMS occasionally reclassifies procedures.

How claims management software catches 37609 errors before submission

Each denial above traces back to a field the operative note left out or a modifier the claim never got. Catching them by hand means re-reading every note against each payer’s rules before the claim goes out.

Pabau’s claims management software flags missing documentation fields before submission. It also tracks each rejection against its medical billing denial codes, so your team can spot patterns and fix the workflow upstream.

Claims go out through Claim.MD, the clearinghouse Pabau integrates with, in CMS-1500 and 837P electronic formats. Claim.MD reaches thousands of US payers, including Medicare and Medicare Advantage plans. Our Claim.MD clearinghouse guide explains how that routing works.

Conclusion

A clean 37609 claim is mostly decided before the patient reaches the procedure room. Check prior authorization during eligibility verification, and make sure the chart already holds the ESR or CRP value and the symptoms behind the GCA suspicion.

After the procedure, the operative note has to name the variant, the side and where the specimen went. Match the bilateral approach to each payer’s rules, and hold follow-up visits against the 10-day global. Those habits cost minutes per claim, while an appeal costs weeks.

Book a demo to see how Pabau flags missing documentation on each 37609 claim before it reaches the payer.

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