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New Category III CPT Codes Now Active for MolecuLight i:X Fluorescence Imaging of Bacteria

The author describes new codes for fluorescence imaging of bacteria and reviews the details clinicians and revenue cycle teams need to know to implement these codes in their practice and billing systems.

In the February issue of Today’s Wound Clinic, readers were made aware of two new category III CPT codes for non-contact fluorescence wound imaging of bacteria.1 Effective July 1, 2020 physicians are directed by the American Medical Association (AMA) CPT Coding Committee to report either 1 or both of these codes when using point-of-care fluorescence wound imaging for bacterial presence, location and load using the MolecuLight i:X® (MolecuLight). Prior to the release of these codes, anatomic specific unlisted codes have been used to report this procedure. Implementation of these new codes, and reporting the procedure and accompanying devices on a claim for payment, enables a reimbursement pathway. This procedure provides real-time images to identify bacteria causing infection in the wound bed and peri-wound regions.

Non-Contact Real-Time Fluorescence Wound Imaging of Bacteria Infection

The two new Category III codes for the MolecuLight i:X procedure are:

0598T Noncontact real-time fluorescence wound imaging, for bacterial presence, location, and load, per session; first anatomic site (e.g. lower extremity)  

0599T each additional anatomic site (e.g. upper extremity) (List separately in addition to code for primary procedure) (Use 0599T in conjunction with 0598T)

The AMA published these two new Category III codes on its website on December 30, 2019 with an update on January 6, 2020. All the Category III codes released on December 30, 2019 will be effective July 1, 2020 and will be published in the 2021 CPT® Manual.2 A description of a coding example is provided in Table 1 to share with your clinical and revenue cycle teams.

The codes described above are needed to report the physician work required to accomplish the new procedure enabled by the MolecuLight i:X handheld portable device when used with the DarkDrape (MolecuLight). Physicians trained on the procedure have become adept at using the handheld device and one wound use DarkDrape to create a portable dark environment necessary for point-of-care identification of the presence, location, and load (>104 CFU/g [colony-forming units per gram) of bacteria] in a wound (Figure 1).3-5 A positive result reports bacteria equal to or >104 CFU/g, which can be indicative of an infection.4-7 Darkened conditions are needed to properly capture the bacteria fluorescence.

The imaging system shines a safe violet light, causing wound components (tissue, bacteria, blood) to fluoresce different colors. Specific fluorescence colors (red or cyan) are indicative of pathogenic bacteria species. Red fluorescence is detected from 87% of common wound pathogens and is indicative of Gram positive and Gram negative species, aerobes and anaerobes (e.g. Staphylococcus, E coli, Klebsiella and others).3,8 Cyan fluorescence is unique to Pseudomonas aeruginosa.3,5 This device detects each of the World Health Organization’s “priority pathogens of concern” (Acinetobacter, Pseudomonas, and the Enterobacteriaceae family), called out by WHO due to multi-drug resistance.9 Clinical value delivered by this new procedure includes real time point-of-care visualization of fluorescence in wounds, and creation of a digital record of all images. Wound area measurements can also be obtained using the device with high accuracy (>95%) and all images can be exported to electronic health records.10

Earlier bacterial detection changes treatment plans and improves patient outcomes. It is well established that the presence of bacterial burden is known to delay wound healing.7 A robust body of clinical evidence validates that use of the MolecuLight i:X procedure facilitates earlier detection of bacteria in the wound bed and peri-wound region. Multiple prospective controlled clinical studies report a 3- to 4-fold improvement in the detection of bacteria in wounds.5,11 (Figure 2) This enhanced detection facilitated more targeted treatment, changing treatment plans in approximately 70% of wounds.5,11 These changes to treatment plans were cost effective and, more importantly, facilitated a positive healing trajectory and reduced time to healing.12,13

Recommendations to Support the Coding Process  

When submitting a claim for payment to your regional Medicare Administrative Contractor (MAC), Medicare Advantage payer, or to a commercial payer, medical documentation is critical to authenticate the medical necessity and appropriate use of the procedure selected to treat the patient’s wound(s). These codes may be used to report physician work across most places of service where a physician or a qualified healthcare provider (QHP) may treat their patient. Use the appropriate place of service code and use the codes 0598T and 0599T to report the physician work as well as the device specific HCPCS codes. Code 0598T describes a wound on one anatomic site, and code 0599T is used to report treatment of a wound on a different anatomic site. If more than one wound was treated per anatomic site, requiring the procedure to be repeated for the second wound, then report the units. As these codes are reported to payers, coding updates will be provided.

Medical documentation should clearly describe the clinical need for verification of the presence of infection and pathogenic bacteria. Include the name of the procedure, “Noncontact Real-Time Fluorescence Wound Imaging, for Bacterial Presence, Location.” Report the specific anatomic site, and the result(s) of the imaging procedure(s). Include the medical decision making, treatments provided and a brief reference as to treatment plan with the knowledge of infection presence or absence. As in all cases of wound treatment, report each wound separately. Provide the anatomic site, wound size, and immediate appearance. Describe the positioning of the patient for imaging with the MolecuLight i:X device and positioning of the DarkDrape (when applicable).

Table 1 includes codes and CMS national average payment for the specific place of service (POS): physician office, physician facility-based payment, hospital outpatient ambulatory payment classification (APC) payment amounts and ambulatory surgery center (ASC). The patient encounter would report procedure codes reflecting the documentation supporting the physician or other QHP work.

Use of HCPCS codes. Procedure codes are used to report the physician work. While these codes have not yet been assigned relative value units, it is important for physicians to consider their total time in preparing the imaging system for use, proper positioning to enable that the correct image will be acquired, and the time and complexity associated with their clinical decision making resulting from the specific information for each wound imaged. HCPCS codes are used to describe the novel durable medical equipment (DME) device related to enabling the physician procedure and the DarkDrape one-wound-use-only supply item.

Both the MolecuLight i:X DME device and the DarkDrape may be reported using miscellaneous HCPCS codes. It is important to report the DME device and single-wound-use DarkDrape (when used) as both are required to enable the procedure. Together they are used to produce fluorescence of bacteria in and around the wound bed at the point of care where it is most important to aid physician decision making.

HCPCS codes are used to report the costs to the provider of the two device components. The portability of this DME and DarkDrape facilitates provision of care across all sites of service including home health care, skilled nursing facilities, and certainly the physician clinic and provider-based departments (PBD). The use of 0598T and 0599T along with the HCPCS device codes on the CMS 1500 form is necessary to capture the physician work and device costs when using the MolecuLight i:X device and DarkDrape for fluorescence imaging of wound bacteria.

Places of service. The MolecuLight i:X procedure can be performed at most places of service including (but not limited to):

05–Indian Health Service Free standing Facility
06–Indian Health Service Provider-based Facility
09–Prison/Correctional Facility
13–Assisted Living Facility
15–Mobile Unit
19–Off Campus - Outpatient Hospital
20–Urgent Care Facility
21–Inpatient Hospital
22–On campus – Outpatient Hospital
23–Emergency room hospital
24–Ambulatory surgical center
26–Military treatment facility
31–Skilled Nursing Facility
32–Nursing Facility
49–Independent Clinic
50–Federally Qualified Health Center
55–Residential Substance Abuse Treatment center
57–Non-residential Substance Abuse Treatment facility

In the current pandemic, the flexible portability of the MolecuLight i:X and DarkDrape has enabled physicians to triage and treat patients in their home care setting due to the restrictions placed on wound care centers. Physicians are making more home visits to provide essential wound care for patients and help patients to avoid visits to clinics, the ER or inpatient setting during the COVID-19 crisis. The variability at site of services, specifically with respect to lighting conditions, necessitates the use of the DarkDrape to create the needed darkened conditions required to perform this medically necessary imaging procedure.

Case Studies

These case studies, taken from prospective controlled clinical trials, lend insight into the imaging information, the physician decision making, and change in treatment decisions.  

Case 1: Point-of-care fluorescence imaging reveals asymptomatic bacterial burden in non-healing wounds.18 A 60-year-old male with type 1 diabetes was being managed at a diabetes limb salvage service for a left plantar heel ulcer of 5 months’ duration. He had a history of Charcot neuroarthropathy with previous midfoot corrective surgery and left calcaneal shaving for a similar ulcer 15 months previously. The patient was compliant with offloading through a total contact cast and had good vascularity. The patient did not have a history of wound infection and was regularly assessed as negative for clinical signs and symptoms of infection, and therefore was being treated with non-antimicrobial dressings and sharp debridement at clinic visits every 4 weeks.

At the time of the clinical visit, the patient was assessed using an internationally recognized checklist for clinical signs and symptoms of infection. No pain, hypergranulation or friable granulation, odor, erythema, warmth, swelling, or purulent discharge were present, but wound breakdown was observed. The patient’s wound had deteriorated from 2.2 cm2 to 7.8 cm2 over the previous 4 weeks.

The wound was therefore imaged with the MolecuLight i:X to determine whether high bacterial loads were present without further symptoms (Figure 3). Fluorescence images were captured after wound cleansing but prior to any debridement, revealing red fluorescence (bacterial loads >104 CFU/g) throughout the periwound region. This region had not been specifically targeted with previous treatment plans. The wound was re-imaged after sharp debridement performed by a vascular surgeon, revealing persistent red (bacterial) fluorescence in the lateral aspect of the wound. As a result, the surgeon changed the treatment plan to include a honey based antimicrobial dressing and more frequent (biweekly) clinical assessments. No antibiotics were prescribed.

Over the next 2 weeks the red fluorescent signal completely resolved, and the wound reduced in size by 45% to 4.37 cm2. Offloading was maintained and the wound continued a positive healing trajectory to closure without further incident.

This is a single case example of how the fluorescence imaging procedure was used by a physician to obtain information on diabetic foot ulcer bacterial presence, load, and location, resulting in a treatment plan change that led the wound to healing. Prospective studies have demonstrated that the periwound region can harbor high bacterial loads that are detected by fluorescence imaging and that treatment plan changes to target these loads through aggressive debridement and the use of antimicrobial agents can eradicate the bacterial fluorescence signal and shift wounds onto a positive healing trajectory.10,12,13,19 A small prospective study by Cole and Coe reports that wounds with red fluorescence on fluorescence images are, on average, experiencing breakdown to increase in size, and that once red fluorescence is eliminated, the wound size begins to rapidly decrease (average weekly area decrease of 27%).12

Case 2: MolecuLight reveals asymptomatic bacterial burden in a non-healing wound. A 39-year-old female suffered a pressure injury on her right hip after a fall left her immobile on the floor for two days. The wound exhibited delayed healing beyond expectations and was present for more than 6 months. The wound measured 2.5 x 0.3 x 0.6 cm. In the two weeks prior, there were no indications of wound infection. At the time of the clinical visit, the patient was assessed using an internationally recognized checklist for clinical signs and symptoms of infection. No pain, hypergranulation or friable granulation, odor, erythema, warmth, swelling, or purulent discharge were present; delayed healing was the only symptom observed. The clinician developed a 4-week treatment plan based on this assessment that consisted of home care visits 3 times/week for wound cleansing with saline, mechanical debridement, and gauze dressing changes, along with continued offloading. In addition, the treatment plan also included biweekly clinic visits for cleansing with HOCL, sharp debridement, gauze dressing, and collagen application.

As part of a prospective, controlled clinical trial, the wound was imaged with the MolecuLight i:X to look for signals from bacteria.11 Images taken after cleansing revealed widespread red fluorescence (indicative of bacterial load >104 CFU/g) throughout the wound bed and surrounding periwound tissues (Figure 4). As a result, the wound was biopsied, and a new treatment plan was recorded to address the bacterial burden detected via fluorescence imaging. The new treatment plan included increased cleaning with HOCL (twice per day), a larger target area for wound hygiene, and biweekly sharply debridement. The presence of bacterial fluorescence also prompted the clinical to add a topical antimicrobial to the gauze dressing. Antibiotics were not prescribed. The fluorescence images were then shown to the patient and used to facilitate patient education and compliance with the new treatment plan. Biopsy results later confirmed a bacterial load of 9 x 105 CFU/g (Staphylococcus and Providencia), a load known to delay wound healing.7

Frequently Asked Questions and Answers

How do I bill for more than one wound on the same anatomic region? When submitting a claim, include units regarding the number of wounds per anatomic site. Support the work with documentation and images from the MolecuLight i:X system. Do report using the DarkDrape or the method used to create the proper darkness to identify the bacteria fluorescence. Code 0599T if there is one wound on a second anatomic site imaged and treated during the same patient encounter.

Can I bill this in addition to debridement or another procedure during the same office visit? It is possible that the patient encounter may be only for the imaging of the bacteria causing infection. However, if other procedures were performed during this patient encounter, then yes, this procedure would be billed in addition to other wound care procedures being performed. If during the patient encounter the wound is cleansed with non-sharp debridement as needed, then imaged once again by using the procedure, the clinician may bill code 97597 as well. Only use codes that explain the physician work and treatments provided at the time of the patient encounter. At this time physicians have billed using the codes as described. Code 0598T with the HCPCS codes E1399 and A4649 for one wound at one anatomic site. When more than one wound was present units were provided if on the same anatomic site. Where additional services were provided, they have billed debridement codes with the MolecuLight i:X procedure. See Table 1 for an example.

If a patient has more than two wounds, would I bill for more than two procedures? If the second wound is within the same anatomic site code 0598T, units to reflect the number of wounds would be reported. Verify in the medical documentation the clinical need for verification of the presence of infection. Report the imaging findings with regards to the presence of pathogenic bacteria if present. If the second wound is on a different anatomic site, then code 0599T would also be used, noting the number of wounds in the second or third sites. Authentication of the medical necessity, results, and clinical decision making is supported with images from the MolecuLight i:X system. Do report the number of DarkDrapes used or the method used to create the proper darkness to identify the bacteria fluorescence.

How many times can I perform the procedure on same patient? Would images be taken weekly? Application of the procedure is based on the clinician’s medical judgement and understanding of the patient’s underlying comorbidities. When providing the medical procedure note the clinical need for verification of the presence of infection and pathogenic bacteria. Wounds with bacterial or infection challenges may need to be imaged more frequently (e.g. biweekly), then less frequently when the infection has been brought under control. Always support the work with documentation and images from the MolecuLight i:X system.

Can I bill for use of this procedure in a long-term care setting? At this time, the two codes may be submitted on the physician bill to report the physician work. The medical documentation would note the place of service, medical necessity, bacterial infection image, findings, and medical decision making, include the treatment or treatment plans. If the physician has brought their entire MolecuLight i:X device and DarkDrape then it would be appropriate to bill for the device components. If the facility purchased the device and DarkDrape, then the physician would not include the HCPCS codes on their claim to the patient’s insurer.

How do I handle a denial? Refer to the payer’s denial resubmission and appeal process. Generally, it is appropriate to resubmit the patient’s claim including all medical documentation from the patient encounter(s). The documentation should include detailed information of the MolecuLight i:X procedure being performed, the place of service, use of the DarkDrape, findings per wound, treatment provided and patient outcome or planned next visit. The company will provide reimbursement hotline assistance to help with the denial process.

What has been the experience thus far before the Category III codes? Healthcare providers have been billing the unlisted procedure codes and the HCPCS codes. Some payers are reimbursing when these codes are provided. Actions are underway to advance payment across the U.S.

Why should I bill a Category III code? Using these codes when reporting the procedure to the patient’s insurance company is part of the necessary process to obtain coverage and payment. Furthermore, as requested by the AMA CPT Coding Committee, use of the code aids tracking the adoption of the new procedure and informs medical insurers about the physician work, needed devices and clinical value of the new procedure.

Which bacterial species are detectable? Evidence to date reports that most common wound pathogens (87%) are detectable once they reach loads of >104 CFU/g, and this includes each of the World Health Organization’s “priority pathogens of concern” (Acinetobacter, Pseudomonas, and the Enterobacteriaceae family), called out by WHO due to multi-drug resistance.8 Earlier detection of these pathogens before an infection begins to spread could alleviate the need for antibiotics, treating them locally instead.

How does this information influence treatment plans? Several prospective studies assessing the impact of the MolecuLight imaging procedure on treatment planning report the information improved decisions leading to more focused treatment. The most frequently reported changes were more extensive wound hygiene (i.e. cleaning or debriding to remove the bacteria), and monitoring of the wound bed to establish readiness for application of skin grafts, substitutes, and other therapies contraindicated when high bacterial loads are present.5,11,12,19,20

Will detecting more wounds with bacteria impact antibiotic overuse? Antibiotics are currently overused in wound care, perhaps more so than in any other medical field contributing to the pervasive problem of antimicrobial resistance (AMR). The lack of objective information on bacteria in wounds is the primary reason for that overuse—the clinician is unsure and so antibiotics are prescribed “just in case.”21 Studies to date have highlighted the significant impact of fluorescence imaging of bacteria on antimicrobial selection, such as choosing a product appropriate against Pseudomonas when a cyan fluorescence colour is seen, or adding a topical antimicrobial, as seen in the example cases.5,11,12 A recent study revealed that use of fluorescence imaging facilitated evidence-based deployment of antimicrobials and more aggressive debridement, putting poorly healing wounds onto a rapid healing trajectory without any use of antibiotics.12

Are patient outcomes improved? Yes, there is compelling evidence from two longitudinal studies showing that elimination of bacterial fluorescence through targeted debridement correlated with accelerated wound area reduction (p=0.017) and increased healing rates (p<0.05).12,13  


Category III codes 0598T and 0599T are available July 1, 2020 to report the novel Non-Contact Real-Time Fluorescence Wound Imaging of Bacteria Infection. Two codes were provided to report wounds on different anatomic sites. At this time miscellaneous HCPCS codes may be used to report the MolecuLight i:X DME device and the one-wound-use DarkDrape to create the mandatory darkness for fluorescence imaging to produce the colors that are related to bacteria location, load and pathogenicity. The DarkDrape is used across physician offices and multiple other patient care settings due to its portability and capability of physicians in their office to remotely work with a QHP at the point-of-care. Growth of the procedure is seen in the inpatient settings and is growing in home health care and domicile settings driven by the COVID-19 restrictions to reduce disease transmission.

A strong body of clinical evidence demonstrates the medical necessity and value of this novel, non-invasive, diagnostic imaging procedure in wound care. Clinical studies consistently report the high reliability of this point of care imaging procedure to accurately detect the presence of infection-causing bacteria in wounds. Earlier detection of bacteria and infection at the point-of-care improves treatment planning and, most importantly, wound outcomes delivering value to the clinician, patient, payers and healthcare system.

Leah Amir, MSc, MHA, is the Executive Director of the Institute for Quality Resource Management.


Leah Amir, MSc MHA

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