Introducing Point-of-Care Diagnostic Imaging of Bacteria to Your Wound Care Practice

The identification of bacteria-causing infection in wounds is key to reducing costs and providing optimal wound care. In this article, the author describes the impact that fluorescence imaging has had on his wound care practice and shares tips on billing for this procedure using reimbursement codes.

_{Disclaimer: This article is intended for general information purposes only and does not constitute legal or professional advice.}

As a wound care clinician, I strive to address the causes that hinder wound healing for my patients and to create the optimal conditions for wound closure. Determining whether the dangerously high levels of bacteria that lead to infection are present in the wound is an essential part of my wound assessment process. It is well established that high loads (>10⁴ CFU/g) of bacteria in wounds are known to delay healing and hinder the effectiveness of many advanced wound therapies (e.g., skin substitutes and grafts).^1-3

The current standard of care to identify bacterial burden in wounds involves looking for clinical signs and symptoms of infection. These symptoms (e.g., erythema, heat, edema, purulent exudate) represent the host response to the presence of bacteria. However, many studies report that clinical signs and symptoms are highly variable and poor predictors of wound infection.^4,5

In my own clinic, I have noticed that typical signs and symptoms of infection are often absent in patients with chronic conditions such as diabetes, in large part because the inflammatory response in these patients is suppressed. Sampling offers minimal assistance; I rarely sample a wound unless I need antibiotic sensitivity information because of delays in obtaining results and lack of reliability (e.g., false negatives).

The poor reliability of these assessment methods may explain why wound healing rates have hardly improved over the last 40 years.⁶ During this time, there have been great advances in treatment options such as negative pressure wound therapy (NPWT) and cellular- and tissue-based products (CTP), yet our healing rates remain virtually unchanged. How could this be?

The reason seems clear: no advanced therapeutics can succeed in wounds when high bacterial loads are present and unaddressed. Without objective evidence to guide treatment decisions, many clinicians rely on “best guesses” to determine whether bacteria are present in wounds.⁷

While in search of new technologies to increase confidence in my wound assessment, I came across the MolecuLight i:X (MolecuLight Inc., Toronto, Canada), a handheld fluorescence imaging device at the Symposium on Advanced Wound Care Spring in 2019. The enthusiasm for this new diagnostic technology was palpable. There was a buzz among optimists and skeptics alike, who were all curious to learn more about how this diagnostic tool could impact their wound care. This imaging technology reportedly enabled clinicians to immediately visualize the presence and location of bacteria in wounds at the bedside and in real time, providing a targeted approach to eliminate bacteria from wounds. The large amount of clinical trial and real-world evidence that was presented on this new imaging technology at the conference made me suspect that this was going to be a much-needed game changer in the field of wound care.

How Fluorescence Imaging of Bacteria Works

The MolecuLight i:X procedure uses a safe, violet light that causes many common wound pathogens that build up within wounds at loads >10⁴ CFU/g to produce red or cyan fluorescent signals.⁸ These signals pass through the device’s optical filters to appear on the device display screen, without any image processing or contrast agents.⁹ Most bacteria emit red fluorescence signals (due to naturally occurring porphyrins) while Pseudomonas aeruginosa emits a cyan fluorescent virulence factor.^8–10 A green fluorescent signal is produced from tissue.⁹

Unlike other imaging technologies, this handheld device requires no new infrastructure and can therefore be used on any wound location, across many sites of service (e.g., private practice, hospital outpatient department, home health etc.), and can be used safely and repeatedly on all patient visits. Fluorescence images need to be captured in absolute darkness. When turning off the lights is not possible or there are windows in the procedure room, a single-use DarkDrape (MolecuLight) can be attached to the device to block out all environmental light. The fluorescence images captured on the device are interpreted by the wound clinician at point-of-care. The safe, visible light means that there is no limit on the duration of the imaging procedure, so wound hygiene and debridement practices can be performed during fluorescence guidance and wounds can be re-imaged to immediately assess treatment efficacy, before additional therapies are prescribed.¹¹

There have been numerous publications highlighting the improved detection that fluorescence imaging has over standard of care wound assessment. The red and cyan colors have very high (>95%) predictive value for indicating moderate-to-heavy loads of bacteria.^10,12 Clinical studies also describe the significant impact of this imaging procedure on improvements in wound bed preparation, application of cellular tissue products, and accelerated wound healing rates.^13-15 In addition to information on the presence and location of bacteria in wounds, the imaging device also contains a highly accurate (>95%) digital wound measurement application, which captures information on wound length, width and area, and documents a manually measured depth.¹¹

How Fluorescence Imaging Informs My Wound Care Practice

At the West Boca Center for Wound Healing, I focus on wound healing and limb salvage and treat many common chronic wounds including diabetic foot ulcers (DFUs) and surgical wounds. An essential component of my wound care is debridement, in which I remove devitalized or bacteria-laden tissue that acts as a barrier to healing and prevents effectiveness of topical antimicrobials and steroids. Determining how much debridement is needed can be a challenge, but the immediate information on the presence and location of bacteria via this device has completely changed my debridement practices. With the fluorescence imaging procedure, I can see bacterial-laden tissues being removed and revealed as I continue to debride.

The immediate diagnostic information and feedback on treatment efficacy I receive with fluorescence imaging of bacteria has been especially valuable during the current pandemic, which limits nonessential hospital admissions and prevents recurrent wound infections. Fluorescence imaging information has also helped me to better understand the infection status of wounds and helps to monitor the effectiveness of my performed and prescribed treatments.

The use of this new diagnostic imaging technology has dramatically changed my outlook and management of all types of wounds. Specifically, it has helped me to better assess and manage the wounds I treat, and provides visual documentation that enhances patient engagement and facilitates better treatment compliance. The immediate feedback on treatment efficacy provided by fluorescence imaging accentuates the need for this type of technology to be used not just for the chronic wound environment, but for acute wounds as well.

How to Navigate Reimbursement of the Fluorescence Imaging Procedure

After realizing the significant clinical utility of diagnostic procedure, one of the first questions that came to mind was “Is there a reimbursement pathway for this procedure?” Knowing that I have adopted this technology into my standard practice, many colleagues have asked me questions as they are interested in identifying which codes are applicable when billing for this procedure. While waiting for the procedure-specific Current Procedural Terminology (CPT) codes to become active as of July 1, 2020, I billed unlisted procedure codes with good success from multiple payers.

However, since July 1, I have begun to use the now-active CPT codes (0598T and 0599T, category III) specifically assigned to this bacterial imaging procedure (Table 1). These codes are for noncontact real-time fluorescence wound imaging, for bacterial presence, location and load, per session at the first anatomic site (0598T) and for each additional anatomic site (0599T). As with other wound care procedures, this procedure can be performed and billed for multiple wounds in a single session, if medically indicated.

Units billed are per wound, not per 20 cm². If, for example, you are performing the imaging procedure on 2 wounds on the same foot, you would ascribe 2 units for 0598T. However, if you are imaging a DFU on a patient’s left foot and then decide to image a second wound on their upper thigh or right foot, you would bill 0598T (1 unit) and 0599T (1 unit). In a hospital outpatient or ambulatory care setting, including ambulatory surgical center (ASC), the procedure CPT codes are mapped to a facility ambulatory payment classification (APC) 5772/T or with designated payment amounts as per Table 1. Codes for the imaging procedure can be applied along with codes for other services provided during the same patient encounter (e.g., debridement, removal of devitalized tissue). In the first month of billing these CPT codes in the physician office setting, there has been good success from multiple payers.

Case Study

Below, I describe a typical case in which I used the fluorescence imaging procedure to inform the treatment and management of a wound.

A 66-year-old patient suffers from poorly controlled diabetes that resulted in amputation of his left foot in 2019. A rotational flap was performed to obtain coverage of the lateral forefoot and remnant flap was left with a >50cm² wound. My treatment strategy aimed to remove any devitalized tissue in and around the wound to reduce the size of the wound and facilitate wound closure. At one of his initial visits earlier this year, I performed standard assessment of the wound for signs and symptoms of infection, and then used the imaging device to take a standard static image of the wound and collect a digital wound measurement of wound area, which is essential to my documentation of wound progress.

I then turned off the room lights and used the imaging device to capture a fluorescence image of the wound to visualize any bacteria present. I immediately noticed bright red fluorescence from bacteria around the edge of the wound (Figure 1), indicating that bacteria at loads >10⁴ CFU/g were present. The presence of fluorescent signals from bacteria indicated to me that additional debridement targeting the wound edge was needed to eliminate bacteria around the wound and help the wound progress to healing.

The following week, the patient came back for a follow-up visit. Under normal room light conditions, I captured a standard image and used it to measure wound area. I was pleased to see a reduction in wound area of 6 cm². After turning off the lights and turning on the fluorescence on the imaging device, I was surprised to see a strong red fluorescent signal from bacteria around the wound edge, particularly the inferior lateral and medial aspects of the limb (Figure 2). This signal was stronger than the previous week and suggested that there were subsurface bacteria requiring treatment. No clinical signs or symptoms had mounted that would have led me to suspect that high levels of bacteria were present without the fluorescence images. The information provided by fluorescence alerted me to the need to perform better exudate management, requiring further debridement and more frequent monitoring of the wound.

With continued use of the fluorescence imaging procedure at each visit, the patient’s wound healing has progressed. The fluorescence signal from bacteria has sharply decreased over time, with recent imaging only performed twice monthly for monitoring purposes. The wound area has dramatically decreased and currently measures 1.75 cm x 1.35 cm x 0.1 cm. The patient has resumed weight bearing exercises and was fitted for a partial foot fill diabetic insert and will resume walking in a few weeks.  

Tips for Billing Codes for the Fluorescence Imaging System

Chronic wounds are often complicated to treat and even more complicated to bill. Below, I share some tips I have learned when billing the bacterial fluorescence imaging procedure codes.

Tip #1: Clear medical documentation for the procedure is critical. As with all procedures seeking reimbursement, medical documentation is critical to authenticate the medical necessity and appropriate use of the procedure selected to treat the patient’s wound(s).

In addition to the description of the patient, these key points should be included in documentation:

o    Describe positioning of patient for imaging and positioning of the DarkDrape™ (if required).

o    Anatomic site, wound size and immediate appearance, clinical need for verification of presence of infection and pathogenic bacteria, list name of procedure (e.g., “Noncontact real-time fluorescence imaging for bacterial presence, location”).

o    Report result(s) of imaging procedure(s). For example, did the fluorescence imaging procedure identify bacteria warranting additional treatment?

o    Include the medical decision-making: treatments provided and reference to treatment plan with knowledge of infection presence or absence.

Tip #2: Billing for multiple wounds. In some cases, 2 wounds at the same anatomic location may be present in a patient. To bill for the imaging of these 2 wounds at the same location, I use 0598T and indicate 2 units. However, many of the patients I treat often have more than 1 wound present in different anatomical locations. When billing, it is important to distinguish imaging of a secondary wound in a unique anatomical location different from the first wound by using code 0599T (Figure 3).  

Tip #3: Frequency of performing the procedure on the same patient. This will depend on the stage of the patient’s care, status of the infection and medical necessity. Table 2 shows what I generally do in my practice.

Tip #4: Billing when performing other procedures. The bacterial imaging procedure is usually one of multiple procedures I perform during a routine patient visit. As an example, if I cleanse a wound with non-sharp debridement, I would then image the wound for bacteria with a DarkDrape to acquire the darkness needed to assess the efficacy of debridement. Table 3 shows what billing may include.

Tip #5: Using the fluorescence imaging procedure when applying advanced therapies (e.g., skin grafts). Given the immediate information provided on bacterial presence and location through the fluorescence imaging procedure, it has become routine in my practice to perform the fluorescence imaging procedure prior to the application of advanced therapies such as CTPs and skin grafts to assess wound readiness for these applications. Fluorescence imaging of the wound provides objective information consistent with the Medicare NCD 270.1 to verify the absence of infection of the wound bed before applying advanced tissue therapies. Fluorescence imaging of bacteria provides me with the certainty that the wound is free of bacterial burden to improve the success rate of these applications. I also use the imaging procedure after applying the CTP or graft to continue to monitor the wound and ensure it continues to remain free from infection.

Tip #6: Billing to category III CPT codes. Readers will see that there is not a payment amount listed for the CPT codes in Table 1. The payment amount of category III CPT is at the discretion of the payer and will vary based on several factors, including medical necessity and the amount clinicians charge. The amount billed should reflect the amount of work required by the physician to perform the procedure (e.g., position the patient, adjust the lighting, capture a clinical image, capture additional images if required due to larger region of the wound, interpret the images, incorporate that new information into a treatment plan, and possibly re-image to monitor treatment efficacy).

Tip #7: Determining which clinicians can bill for the imaging procedure CPT codes. A clinician billing to these CPT codes (0598T and 0599T) must be credentialed for services provided (i.e., credentialed to provide wound care). Generally, any clinician treating a wound (acute or chronic) who is credentialed to do so can bill this procedure (e.g., MD, DPM, WOCN).

Tip #8: Billing the CPT code when performing the procedure in an inpatient setting, where cost of care is bundled under an Medicare Severity-Diagnosis Related Group (MS-DRG) determined amount. Like other procedures, the physician would bill for their work performing the MolecuLight-enabled procedure. This would be billed by the physician separately from the facility’s MS-DRG bundled payment for that inpatient.

Tip #9: Handling a denial. Any procedure is at risk of denial, making medical documentation critical. Refer to the payer’s denial resubmission and appeal process. It is typically appropriate to resubmit the patient’s claim including all medical documentation from the patient encounter(s). MolecuLight Inc. does provide reimbursement hotline assistance (https://us.moleculight.com/reimbursement/) to help with the denial process.

Tip #10: Applying the APC code. APC codes are used to report services provided in hospital outpatient (HOPD) setting. These codes could be used when the facility bills from off campus or on campus outpatient hospital, emergency room, and ambulatory surgical center settings. The patient encounter would report procedure codes reflecting the documentation supporting the physician work.

Tip #11: Reimbursement of supplies used for the fluorescence imaging procedure. Currently, there are no HCPCS codes specific to the MolecuLight i:X procedure. However, both the MolecuLight i:X DME device and DarkDrape (single use attachment for when lights cannot be turned off) may be reported using miscellaneous HCPCS codes (e.g., E1399 for durable medical equipment, A4649 for miscellaneous surgical supply) if used in sites of service including physician office, home health, and skilled nursing facility. If multiple DarkDrapes are used, then multiple units of A4649 would be billed.

Eric Lullove, DPM, CWSP, FACCWS, FAPWCA, is the Chief Medical Officer of the West Boca Center for Wound Healing in Coconut Creek, FL.

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