CPT code 37766 – Stab phlebectomy of varicose veins

Key takeaways

CPT Code 37766 covers stab phlebectomy of varicose veins on one extremity with more than 20 incisions. The count is what separates it from 37765, which covers 10-20 incisions.

The operative note must state an explicit count above 20. Vague wording such as ‘multiple incisions’ is an audit risk and a common denial trigger.

Medicare requires duplex ultrasound documentation and proof that conservative therapy failed before varicose vein procedures qualify for coverage under MAC LCDs.

Medicare has applied a 10-day global period to 37766 since January 1, 2020.

Pabau’s claims management software runs validation checks before submission and sends claims electronically through Claim.MD.

CPT Code 37766: Official descriptor and procedure overview

CPT Code 37766 is the code for stab phlebectomy of varicose veins on one leg when more than 20 incisions are made in one session. The American Medical Association (AMA) publishes it with the official descriptor “Stab phlebectomy of varicose veins, 1 extremity; more than 20 incisions.”

It sits in the venous procedures range of the CPT surgery section. The procedure is done under local anesthesia in an office, an ambulatory surgical center (ASC), or an outpatient hospital.

The varicose tributaries are marked before surgery with the patient standing. The surgeon then makes 1-3 mm stab incisions along the marked veins, extracts vein segments with a phlebectomy hook, and applies compression. Each stab incision counts toward the 37766 threshold. When the total exceeds 20 on one extremity in one session, 37766 is the correct code.

Key billing facts at a glance

CPT 37766 vs. 37765: Choosing the right code

The difference between 37765 and 37766 is the incision count. 37765 applies when 10-20 incisions are made. 37766 applies when more than 20 incisions are made on one extremity in one session.

Both codes are per-extremity, per-session codes. Billing 37765 when the operative note documents 23 incisions is an undercoding error. Billing 37766 when only 18 incisions were made is an overcoding risk.

The operative note is the audit trigger. Payers will not accept “multiple stab incisions” as documentation for 37766, because the count has to appear as a number. If the count is not recorded during the procedure, code the claim to 37765 or hold it until a compliant addendum amends the note. The decision below runs per leg, per session.

Related varicose vein codes and when to use them

Varicose vein treatment involves several distinct CPT codes depending on technique. Using the wrong code family is a common error when a practice treats both the saphenous trunk and tributaries on the same day.

Documentation requirements for CPT Code 37766

The operative note is the single most important document for 37766 claims. Payers and Medicare auditors check it against a defined list of required elements. Missing any one of these can trigger a denial or a post-payment audit finding.

• Explicit incision count: The note must state a number greater than 20 (“22 stab incisions,” not “multiple incisions”). Vague language does not support 37766.
• Anatomical location and laterality: Identify the specific vein segments treated and state whether the procedure was performed on the right or left leg.
• Procedure technique: Document hook phlebectomy, vein extraction segments removed, and wound closure method.
• Pre-operative diagnosis: Link the procedure to a supporting ICD-10 diagnosis code (see ICD-10 pairings below).
• Conservative therapy failure: For Medicare and most commercial payers, document that compression therapy and lifestyle modification were attempted and inadequate before proceeding to phlebectomy.
• Duplex ultrasound findings: Attach or reference the pre-operative duplex study confirming reflux or tributary disease. Medicare LCDs require this.

A superbill template with an incision-count field, filled in during the procedure, puts the number on record before the claim is submitted.

Modifiers for CPT Code 37766

Modifier selection for 37766 depends on laterality, whether multiple procedures are performed on the same date, and whether an assistant surgeon was involved. Attaching the wrong modifier, or omitting one, is a leading cause of denials on phlebectomy claims.

Medicare coverage, LCDs and prior authorization

Medicare covers stab phlebectomy under CPT Code 37766 when the claim meets the criteria established in the applicable MAC Local Coverage Determination (LCD). Coverage is not automatic.

In Novitas jurisdictions the governing LCD is L34924, “Treatment of Chronic Venous Insufficiency of the Lower Extremities.” CGS, Palmetto GBA, and WPS publish their own equivalents. Each sets out clinical criteria that must be met and documented before the claim can be approved.

Core LCD requirements

• Conservative therapy failure: The patient must have tried compression therapy (typically graduated stockings, 20-30 mmHg or greater) for at least 6-12 weeks. The record must show it failed to relieve symptoms. Duration requirements vary by MAC.
• Duplex ultrasound documentation: A pre-operative duplex ultrasound confirming venous reflux or tributary disease is required. The ultrasound report must be available in the medical record at the time of claim submission.
• Symptomatic disease: Asymptomatic varicose veins (coded I83.9x) generally do not meet Medicare medical necessity criteria. Symptoms must be documented: pain, swelling, aching, heaviness, or skin changes (ulceration, hyperpigmentation, lipodermatosclerosis).
• Prior authorization: Medicare does not require prior authorization for most varicose vein procedures, but many Medicare Advantage plans do. Check plan-level authorization requirements before scheduling. Commercial payers frequently require prior auth with clinical documentation including the duplex report and conservative treatment records.

MAC LCD policies are jurisdiction-specific. Practices billing to Novitas (jurisdictions H and L) should verify against L34924, and CGS practices should check their equivalent LCD. A Medicare Coverage Database search returns the current LCD and billing article for your MAC.

2026 Medicare reimbursement rates for CPT 37766

The 2026 Medicare Physician Fee Schedule rates for CPT Code 37766 are published in the CMS PFS Look-Up Tool. Always verify current-year rates in the CMS Physician Fee Schedule search. Rates change every year and vary by locality through the Geographic Adjustment Factor (GAF).

The figures below represent national non-facility and facility averages for 2026 and should be confirmed for your specific MAC jurisdiction.

For current RVU values by component, use the FastRVU 2026 RVU lookup tool, which reflects the final 2026 CMS PFS data. Commercial payer rates for 37766 typically exceed Medicare rates but vary by contract, so confirm them against each payer’s fee schedule.

Common denial reasons for CPT 37766 and how to prevent them

Most 37766 denials share a small set of root causes. Each one comes back on the remittance with a reason code, and our guide to denial codes explains how to read them. Fix the cause in the note or the claim template, and the same denial stops recurring.

Effective denial management starts before the claim leaves the office. Check the operative note, the modifiers, and the supporting records against the table above while the procedure is still fresh.

Bundling and same-day billing rules for CPT 37766

NCCI (National Correct Coding Initiative) edits govern which codes can be billed together on the same date of service. The key bundling scenarios for 37766 involve same-day endovenous ablation and bilateral phlebectomy.

• 37766 billed with 36475 (endovenous ablation, same leg): NCCI may bundle phlebectomy with same-session thermal ablation billed as 36475 on the same extremity. Whether modifier 59 can break the bundle depends on current PTP edits. It also depends on whether the procedures were performed on distinct anatomical segments. Always verify the current NCCI PTP table before submitting this combination.
• 37766 billed bilaterally (both legs, same session): This is not a bundling issue but a modifier issue. Bill 37766-LT and 37766-RT as separate line items, or use modifier 50, according to payer preference. Document bilateral treatment explicitly in the operative note.
• 37766 billed with 37765 on the same extremity: Not appropriate. The two codes are mutually exclusive for the same extremity on the same date. Use only the code that reflects the documented incision count.
• 37766 billed with sclerotherapy 36471 (same session): Sclerotherapy billed as 36471 is generally payable alongside 37766 when it treats different sites. Some payers still bundle phlebectomy and sclerotherapy performed at the same visit. Verify with the specific payer, and attach modifier 59 with supporting documentation when claiming distinct services.

Understanding what makes a clean claim before submission is the most effective way to avoid NCCI-related denials. Build a same-day procedure checklist that cross-checks the NCCI PTP table for every common 37766 pairing your practice bills.

ICD-10 codes commonly paired with CPT 37766

The ICD-10 diagnosis code paired with 37766 directly affects medical necessity review. Payers match the diagnosis to the procedure and apply LCD criteria. Asymptomatic varicose veins coded I83.9x rarely meet Medicare’s coverage threshold without additional documented complications.

The AAPC Codify CPT lookup cross-references CPT codes with the ICD-10 diagnoses that support them. Electronic remittance advice also shows when a denied claim failed medical necessity on the diagnosis code used. Tracking these through ERA management speeds the root-cause identification.

How claims management software protects CPT 37766 claims

Most phlebectomy billing still runs on a checklist and a clearinghouse portal. Someone reads the operative note, keys the code and modifiers, and learns about a missing authorization when the denial arrives.

Pabau, the practice management platform we build, keeps the appointment, the clinical notes, and the claim in one patient record. Its claims software for phlebologists runs validation checks on membership numbers and authorization codes before a claim goes out. It also runs real-time eligibility checks and submits claims electronically through Claim.MD.

Each claim then moves through a visible status, from pending to submitted, processing, and paid, and ERA remittances post against it. Your team spots a rejected 37766 line within days and corrects it while the operative note is still fresh.

Streamline varicose vein billing with Pabau

Pabau checks each claim before submission, sends it through Claim.MD, and tracks every 37766 line until it is paid.

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Conclusion

Most 37766 denials trace back to the operative note, so the fix starts in the procedure room. Make the exact incision count a required field, and confirm laterality and the duplex report before the claim is submitted.

The trade-off is a minute of extra documentation per leg against a full resubmission cycle. Once the count lives in the note template, the most common phlebectomy denial stops appearing.

Book a demo to see how Pabau checks and tracks vein procedure claims from submission to payment.

Continue your research

Want to understand how claims move from code to payment? Claim.MD clearinghouse guide explains how electronic claims are validated, submitted, and tracked through the payer network.

Looking for a plain-language overview of the billing cycle? Revenue cycle management explained covers the end-to-end process from patient check-in to payment posting.

Planning a phlebectomy for a Medicare Advantage or commercial patient? The prior authorization process walks through what to submit and when.

Billing traditional Medicare for vein procedures? Medicare billing covers enrollment, claim forms, and the rules that decide payment.

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