Is ambulatory phlebectomy (37765, 37766) medically necessary for a patient with varicosity on the back of their left leg, who has failed conservative treatment and has severe and persistent pain and swelling?

Medical Necessity Assessment for Ambulatory Phlebectomy (CPT 37765,37766)

This ambulatory phlebectomy is NOT medically necessary because the patient fails to meet the critical vein diameter criterion of ≥2.5mm required for phlebectomy procedures, despite meeting all other clinical criteria.

Critical Missing Criterion: Vein Diameter

The clinical policy bulletin explicitly requires vein diameter ≥2.5mm for ambulatory phlebectomy to be medically necessary 1. The ultrasound documentation shows:

• Tributary behind left knee: 4.5mm - MEETS criterion 1
• Tributary in left calf: 2.1mm - FAILS criterion (below 2.5mm threshold) 1

The 2.1mm tributary vein is too small for phlebectomy to be effective. Evidence demonstrates that vessels <2.0mm treated with sclerotherapy had only 16% primary patency at 3 months compared to 76% for veins >2.0mm, and treating veins smaller than 2.5mm results in poor outcomes with lower patency rates 1. This same size principle applies to phlebectomy procedures 1.

Criteria Analysis: What Was Met vs. Not Met

Criteria Successfully Met:

• Conservative therapy trial: 3 months of 20-30mmHg compression stockings, leg elevation, and NSAIDs 1
• Symptomatic disease: Pain, throbbing, and achiness limiting daily activities and quality of life 1
• Reflux documentation: Tributary reflux >2 seconds documented on recent ultrasound (09/03/2025) 1
• Prior junctional treatment: Previous RFA of left GSV addresses saphenofemoral junction incompetence 1

Critical Criterion NOT Met:

• Vein diameter requirement: The 2.1mm calf tributary does not meet the ≥2.5mm threshold required for phlebectomy 1

Clinical Context and Alternative Considerations

Why This Criterion Matters:

The physician's documentation describes a "large" varicosity that "blows up to a larger balloon-like area on the skin surface" with slight ulceration and bleeding predisposition. However, the ultrasound measurement at the vein's origin (2.1mm) is what determines medical necessity, not the superficial appearance 1.

The Discrepancy Problem:

There appears to be a mismatch between:

• Clinical appearance: "large" varicosity with surface dilation
• Ultrasound measurement: 2.1mm at origin
• Policy requirement: ≥2.5mm diameter

This discrepancy suggests either:

1. The vein diameter should be re-measured at the widest point rather than just the origin 1
2. Alternative treatment modalities may be more appropriate 1

Alternative Treatment Pathway

If Vein Diameter Remains <2.5mm:

Foam sclerotherapy would be the appropriate intervention rather than phlebectomy, as sclerotherapy is indicated for smaller tributary veins 1. However, even for sclerotherapy, vessels <2.0mm have poor outcomes 1.

If Re-measurement Shows ≥2.5mm:

Phlebectomy would become medically necessary given that all other criteria are met, including:

• Documented reflux >2 seconds 1
• Failed conservative management 1
• Symptomatic disease interfering with activities of daily living 1
• Prior treatment of saphenofemoral junction 1

Recommendation for Authorization

DENY the current request pending re-evaluation with the following requirements:

1. Obtain updated ultrasound measurements documenting vein diameter at the widest point of the varicosity, not just at the origin 1
2. If diameter remains <2.5mm: Consider foam sclerotherapy as alternative treatment 1
3. If diameter ≥2.5mm on re-measurement: Resubmit with updated documentation showing compliance with size criteria 1

The presence of slight ulceration and bleeding risk does not override the fundamental size requirement for procedure selection, as using the wrong modality for vein size leads to poor outcomes and higher recurrence rates 1, 2.