ModifiedUnitedHealthcarePolicy CS132TN.O

Noncontact Warming Therapy, Ultrasound Therapy, and Fluorescence Imaging for Wounds (for Tennessee Only)

Coverage determinations for NNWT, low-frequency ultrasound therapy, and real-time fluorescence wound imaging for Tennessee Medicaid and CoverKids members.

Policy Summary

PayerUnitedHealthcare

PolicyNoncontact Warming Therapy, Ultrasound Therapy, and Fluorescence Imaging for Wounds (for Tennessee Only)

Policy CodePolicy CS132TN.O

Change TypeCode list and description updates

Effective DateFeb 1, 2026

Next Review DateN/A

Key ActionVerify and use the updated CPT codes (e.g., 0598T, 0599T) for any prior authorization submissions.

SourceLink

POLICY UPDATE CHANGES

Updated list of applicable CPT codes to reflect annual edits and revised descriptions for 0598T and 0599T.

Archived previous policy version CS132TN.N.

Tennessee Medicaid & CoverKidsapplicability

0598T,0599T,97610,A6000,E0231,E0232codes listed in policy

Not medically necessarycoverage stance

0598T,0599Tcodes revised

92.6%

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sensitivity (high loads)

Coverage Determinations and Rationale

Not medically necessary determinations

Covered when criteria below are met; otherwise services are considered not medically necessary.

Warming therapy (NNWT): Warming therapy or noncontact normothermic wound therapy (NNWT) is considered unproven and not medically necessary for treating wounds due to insufficient evidence of efficacy.

Supported by systematic reviews and reviews of RCTs that found no randomized trials or found studies limited by small sample sizes, lack of controls or randomization, and short follow-up (see Yue et al. 2018).

Low-frequency ultrasound therapy (contact and noncontact) is considered unproven and not medically necessary for treating wounds due to insufficient evidence of efficacy.

Evidence base includes small, heterogeneous trials and systematic reviews/meta-analyses with methodological limitations and imprecision (see Chen et al. 2023; Flores-Escobar 2022; Cullum & Liu 2017).

Real-time fluorescence wound imaging: Noncontact real-time fluorescence wound imaging for detection of bacterial presence (e.g., MolecuLight i:X) is considered unproven and not medically necessary due to insufficient evidence of safety and/or effectiveness in improving patient-centered outcomes.

Diagnostic accuracy and observational studies report increased sensitivity for detecting moderate-to-heavy bacterial loads, but ECRI and NICE assessments conclude evidence is inconclusive for improved clinical outcomes. Additional RCTs are needed.

Coverage considerations for ultrasound and fluorescence imaging

Evidence-based coverage considerations drawn from clinical trials and meta-analyses:

Ultrasound therapy (low/high frequency): Consider use of therapeutic ultrasound only after standard-of-care treatments have been tried and documented and when the proposed ultrasound regimen matches protocols with demonstrated benefit in trials.

Some meta-analyses and small RCTs report benefit for specific ultrasound-supported debridement regimens (e.g., more frequent noncontact low-frequency ultrasound in small DFU trials), whereas a larger RCT of weekly low-dose high-frequency ultrasound showed no healing benefit and increased adverse events; therefore clinical justification and alignment with evidence-based protocols are required.

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Warming therapy, including noncontact normothermic wound therapy (NNWT), is considered unproven and not medically necessary for the treatment of wounds due to insufficient evidence of efficacy. Similarly, low-frequency ultrasound therapy (contact or noncontact) is considered unproven and not medically necessary for wound treatment because the published literature does not demonstrate consistent patient benefit. The policy also states that noncontact real-time fluorescence wound imaging for detection of bacterial presence is unproven and not medically necessary because evidence for safety and effectiveness is insufficient.

Devices and related indications that lack evidence of improving patient-centered outcomes — including handheld fluorescence imaging systems (regardless of FDA clearance) and ultrasound or warming devices when proposed as standalone therapies — are not supported by the available literature. The policy emphasizes that additional clinical studies are required to validate safety and efficacy before these technologies can be relied on as independent justifications for coverage or replacement of standard wound care.

Clinical practice guidelines from the American Podiatric Medical Association (in collaboration with the Society for Vascular Surgery and Society for Vascular Medicine) do not include warming therapy, NNWT, or low-frequency ultrasound for diabetic foot management. NICE similarly reports limited evidence and does not recommend routine adoption of certain ultrasound systems (MIST Therapy) or concludes evidence is insufficient to show that MolecuLight i:X reduces wound closure time or improves antibiotic stewardship.

This Medical Policy is provided for informational purposes to assist in interpreting UnitedHealthcare standard benefit plans and does not constitute medical advice. Coverage determinations must follow applicable federal, state, or contractual benefit plan requirements, which take precedence where terms differ. Before applying this policy to coverage decisions, confirm and document the governing benefit terms.

The policy states that warming therapy (NNWT), low-frequency ultrasound therapy, and noncontact real-time fluorescence wound imaging are considered unproven. Given the current evidence base, the policy does not support routine coverage of these therapies for wound management.

A large multicenter randomized controlled trial (Watson et al., 2011; n=337) evaluated weekly, low-dose, high-frequency ultrasound added to standard care for hard-to-heal venous leg ulcers and found no significant difference in time to healing compared with standard care alone; the ultrasound group experienced more adverse events. Based on these results, routine weekly administration of this ultrasound regimen did not improve healing and therefore is not supported as standard therapy.

Independent evidence assessments have concluded that available data are inconclusive or limited. An ECRI clinical evidence assessment concluded evidence for the MolecuLight i:X system is inconclusive and insufficient to determine improvement in patient outcomes, and NICE concluded the evidence for MIST Therapy and MolecuLight i:X is limited and not sufficient to support routine adoption.

Procedure and Supply Codes

Procedure CPT/HCPCS codes listedmixed

0598T	Real-time fluorescence wound imaging with clinical darkness, to identify location of bacterial wound pathogens and measure wound size, per session; first anatomic site (e.g., lower extremity, right leg).
0599T	Real-time fluorescence wound imaging with clinical darkness, to identify location of bacterial wound pathogens and measure wound size, per session; each additional anatomic site (e.g., upper extremity, left leg) (List separately in addition to code for primary procedure).
97610	Low frequency, non-contact, non-thermal ultrasound, including topical application(s), when performed, wound assessment, and instruction(s) for ongoing care, per day

Supply/Device HCPCS codes listedHCPCS

A6000	Noncontact wound-warming wound cover for use with the noncontact wound- warming device and warming card
E0231	Noncontact wound-warming device (temperature control unit, AC adapter and power cord) for use with warming card and wound cover.
E0232	Warming card for use with the noncontact wound warming device and noncontact wound warming- wound cover

No codes in this document segmentmixed

No codes listed

Regulatory clearances referencedmixed

510(k)

FDA premarket notification clearance status referenced for multiple devices (Warm-Up, MIST Therapy, UltraMIST, MolecuLight i:X)

Updated CPT CodesCPT

0598T	Description revised per policy history (exact revised description referenced in policy)
0599T	Description revised per policy history (exact revised description referenced in policy)

inv-17: Fluorescence detection threshold — device detection limits and referenced microbiology thresholds

Device detection lower limitFluorescence imaging in studies localized moderate-to-high bacterial loads with a detection threshold reported at >10^4 CFU/g (10,000 CFU/g)

Microbiology thresholds citedSome microbiology thresholds of clinical concern referenced at 10^5 CFU/g in context of wound pathogenicity (studies compare across 10^4–10^9 CFU/g)

Clinical study useArmstrong et al. used quantitative tissue culture to confirm loads and compared fluorescence sensitivity across thresholds from 10^4 to 10^9 CFU/g

Billing, Documentation, and Authorization Guidance

Prior Authorization

Prior authorization not specified

Prior authorization is not specified in this policy excerpt. FDA clearance of devices is informational only and does not by itself establish coverage or prior authorization requirements. Providers should verify any plan-specific prior authorization requirements with the member’s benefit plan or payer portal before delivering services.

FDA clearance is informational only — does not imply coverage (see FDA section).
Check plan/payer portals for any plan-specific prior authorization requirements.

Billing Rule

Use updated CPT codes for submissions

Verify and use updated CPT codes on claim submissions. The policy’s Applicable Codes were updated effective 02/01/2026; providers must ensure coding reflects annual CPT/HCPCS edits and the most current code descriptors when billing.

Background and Evidence Base

Noncontact normothermic wound therapy (NNWT) applies radiant heat and maintained humidity to the wound using a noncontact wound cover and a warming unit. The intended physiologic effects include raising wound temperature to increase local blood flow and tissue oxygenation, which are hypothesized to support wound healing; however, clinical studies to date have not established consistent patient benefit.

radiant heatApplies radiant heat via noncontact wound cover

100%Relative humidity maintained in wound dressing

temperature upIntended to raise wound temperature to increase blood flow/oxygen

40 kHzUltrasound frequency of MIST Therapy (approx.)

1 cmHandset distance from wound during treatment

saline mistDelivers ultrasonic energy via saline mist

Policy Changes and Versioning

2026-02-01codes_updatedLatest

Updated list of applicable CPT codes to reflect annual edits; revised descriptions for CPT 0598T and 0599T; previous policy version CS132TN.N archived.

Policy Summary

PayerUnitedHealthcare

PolicyNoncontact Warming Therapy, Ultrasound Therapy, and Fluorescence Imaging for Wounds (for Tennessee Only)

Policy CodePolicy CS132TN.O

Change TypeCode list and description updates

Effective DateFeb 1, 2026

Next Review DateN/A

Key ActionVerify and use the updated CPT codes (e.g., 0598T, 0599T) for any prior authorization submissions.

SourceLink

On This Page

Updated CPT codes effective 02/01/2026 per Policy History.
Use current AMA CPT/HCPCS code sets and payer billing guidelines when submitting claims.

Denial Risk

Denial risk for not medically necessary services

Claims for services that do not meet the policy’s medical necessity criteria — or that lack clinical documentation demonstrating medical necessity — may be denied. Services described as unproven or not medically necessary in this policy (for example, noncontact normothermic wound therapy, low frequency ultrasound therapy, and noncontact real-time fluorescence wound imaging when used outside supported indications) are subject to denial if not medically necessary per the governing benefit terms.

Noncontact NNWT, low frequency ultrasound, and fluorescence imaging are described as unproven/not medically necessary in this policy.
Deny if documentation does not support medical necessity per plan terms.

Note

No explicit coverage authorization from FDA clearance

There is no explicit coverage authorization conferred by FDA clearance noted in this policy. FDA 510(k) clearance indicates regulatory status only; coverage decisions are determined by the payer and by applicable federal, state, and contractual benefit terms.

FDA 510(k) clearance for devices (e.g., MolecuLight i:X, MIST Therapy System) is informational and not a coverage determination.
Coverage requires alignment with governing benefit terms, not solely FDA status.

Note

Check governing benefit terms

Always check the member’s governing benefit plan terms (federal, state, or contractual) before rendering or billing services. In the event of conflict between this standard policy and the member’s benefit plan, the plan-specific terms govern coverage and payment.

Reference federal, state, or contractual benefit requirements when making coverage determinations.
When plan terms conflict with this policy, the plan-specific requirements govern.

Documentation Required

Coding and device documentation

Document the specific service, device, and wound characteristics in the medical record. For device-based wound therapies, include device make/model, settings used, anatomic site(s) treated, number of sites, and whether single-use disposables were utilized.

Record device manufacturer and model (e.g., MolecuLight i:X, MIST Therapy System, Warm‑Up).
Document anatomic site(s), number of sessions, device settings, and disposables used.

Documentation Required

Suggested documentation elements from studies

When citing clinical support for imaging- or device-guided interventions, include suggested documentation elements used in referenced studies: wound images (fluorescence photos), microbiology results (swab/biopsy cultures, PCR/NGS where available), descriptions of actions taken based on imaging (e.g., targeted debridement, altered antimicrobial therapy), and wound measurements over time.

Include fluorescence images and correlate with microbiology (swab/biopsy) when performed.
Document clinical actions taken as a result of imaging findings and serial wound measurements.

Note

Reference benefit plan terms

Reference the member’s benefit plan terms when determining coverage and reimbursement. This policy is an interpretive aid for UnitedHealthcare standard plans; specific federal, state, or contractual language may mandate different coverage or exceptions.

This policy assists in interpretation but does not override plan-specific contractual language.
Confirm any mandatory coverage provisions in the member’s benefit plan prior to rendering services.

Step Therapy

Step therapy consideration

Step therapy and standard-of-care sequencing should be considered. Per guideline and evidence summaries, foundational therapies (e.g., compression and moisture-retentive dressings for venous ulcers) should be optimized before adjunctive device therapies are used.

Optimize standard care (compression, moisture-retentive dressings) before adjunctive ultrasound or warming therapies.
Document prior use and failure or contraindication of first-line therapies if proposing adjunctive device-based treatments.

Note

Adjunctive/second-line positioning in guidelines

Device-based therapies and imaging are generally positioned as adjunctive or second-line per cited guidelines and evidence assessments. Use of ultrasound stimulation, warming therapy, or fluorescence imaging should follow established first-line wound care approaches and be supported by documentation when used as secondary therapies.

Guidelines place device therapies as adjunctive/second-line; evidence strength is limited.
Provide documentation showing rationale for adjunctive use and prior attempts at standard therapies.

violet lightIllumination modality used to elicit bacterial fluorescence

real-timeProvides real-time imaging at point of care

documentCaptures and documents presence/location of bacteria

inv-38: Chronic inhibitory bacterial load (CIBL) — definition and threshold context

DefinitionChronic inhibitory bacterial load (CIBL) denotes a bacterial burden threshold associated with impaired healing, referenced in studies at ≥10^4 CFU/g

Context in DFU studiesArmstrong et al. reported 93.9% of DFUs had loads >10^4 CFU/g and proposed CIBL to prompt earlier intervention

Clinical implicationCIBL is used to encourage earlier bacterial-directed interventions, monitoring treatment effectiveness, and antimicrobial stewardship

inv-39: Fluorescence wound imaging — general definition of handheld devices that visualize bacterial fluorescence

General definitionHandheld, noncontact devices that visualize bacterial fluorescence and measure wound surface area in real-time to localize elevated bacterial loads and biofilm at point of care

Intended useUsed to improve detection of moderate-to-heavy bacterial burdens that may be missed by clinical signs and symptoms alone

Evidence noteSafety and efficacy have not been established; additional clinical studies are needed to validate clinical utility

inv-40: Fluorescence imaging (MolecuLight i:X) — device autofluorescence imaging to identify moderate-to-heavy bacterial loads

Device descriptionMolecuLight i:X is a handheld autofluorescence imaging device that uses violet light to generate images showing red or cyan fluorescence to identify wound areas with moderate-to-heavy bacterial loads

Performance evidenceObservational and pilot studies report higher sensitivity than clinical signs for detecting bacterial loads >10^4 CFU/g, but evidence for improved patient outcomes is inconclusive (ECRI)

Recommended use in studiesStudies recommend using MolecuLight i:X alongside clinical signs and symptoms and correlating imaging with microbiology when possible

inv-41: MIST / low-frequency ultrasound therapy — device and intended mechanism summary

Modality summaryMIST / low-frequency ultrasound therapy delivers low-energy ultrasound (airborne or mist) intended to promote wound healing through wound cleansing and maintenance debridement by removal of slough, fibrin, exudates, and bacteria

Regulatory statusMIST Therapy System is regulated as an FDA Class II device cleared via 510(k) (MIST, UltraMIST) for producing a low-energy ultrasound-generated mist to promote wound healing

Evidence contextNICE notes potential to enhance healing but concludes published evidence is insufficient for routine adoption; RCTs are heterogeneous

inv-42: Warm-Up / warming therapy — occlusive heated dressing system description

Device descriptionWarm-Up / warming therapy uses an occlusive heated dressing system (wound cover and temperature control unit) to apply radiant heat and maintain humidity to raise wound temperature

Intended mechanismAims to increase local blood flow and oxygenation to support wound healing via normothermic wound therapy

Regulatory infoWarm-Up Active Wound Therapy received FDA 510(k) clearance as an occlusive heated dressing (product code MSA)

inv-43: Noncontact low-frequency ultrasound — evaluated modality in RCTs and comparative studies

Modalities evaluatedNoncontact low-frequency ultrasound has been assessed in randomized and comparative studies as an adjunctive treatment for chronic wounds and pressure injuries

Study typesEvidence includes randomized, double-blind sham-controlled trials and pilot studies (e.g., Rastogi et al. 2019; White et al. 2016; Yao et al. 2014)

Evidence limitationsTrials are heterogeneous in frequency, dose, and outcomes; larger RCTs have shown no consistent benefit for some regimens and reported more adverse events in certain protocols

inv-44: Fluorescence bacterial imaging — real-time imaging technology to identify moderate-to-heavy bacterial burden

Technology overviewFluorescence bacterial imaging is a real-time imaging technology that detects red or cyan bacterial autofluorescence to identify wounds with moderate-to-heavy bacterial burden

Diagnostic performanceStudies report improved sensitivity and accuracy versus clinical assessment alone for detecting bacterial loads ≥10^4 CFU/g, with sensitivity peaking at higher loads (e.g., up to 92.6% for >10^8 CFU/g)

Limitations notedLimitations include shallow depth of excitation (~1.5 mm) and inability to detect non-porphyrin-producing bacteria; clinical utility for patient-centered outcomes remains unproven