A duplex scan is a type of ultrasound exam designed to evaluate the pattern and direction of blood flow in arteries and/or veins. A duplex scan includes both conventional ultrasound (B-mode) and two different types of Doppler ultrasound – spectral Doppler and color Doppler. Ensuring there is both performance and documentation of these elements is critical to appropriate claim submission and reimbursement.
Spectral Doppler imaging provides a graphic display of Doppler data which are jagged vertical lines called waveforms. If spectral Doppler was performed, the report will usually include a mention of waveforms or resistive index (RI). Color Doppler imaging provides a color image of the vessel superimposed on a B-mode ultrasound image. The B-mode (grayscale) image shows the vessel structure and the color shows the velocity and direction of flow.
Both spectral and color flow Doppler must be performed in order to report a duplex code. The CPT® manual states that a duplex scan involves the production of “real-time images integrating B-mode two-dimensional vascular structure, Doppler spectral analysis, and color flow Doppler imaging.”
To ensure correct billing and avoid problems in the event of a payer audit, the radiologist should document the specific exam protocol. Clinical Examples in Radiology (Spring 2012) states:
“At the very minimum, the technique part of the report should state that ‘A duplex Doppler study was performed.’ Ideally, it should state, for example, ‘A duplex Doppler study was performed, consisting of integrated two-dimensional (2D) real-time imaging color flow Doppler and Doppler spectral analysis utilizing 5.0 MHz and 7.0 MHz linear array probes.’ The body of the report should optimally describe that normal flow, compressibility, and augmentation were demonstrated on Doppler spectral analysis.”
If the physician specifically states that a duplex study was performed, this implies performance of B-mode 2D, color Doppler and spectral Doppler. If the physician does not document that a duplex study was performed, then both color and spectral Doppler must be specifically documented. Documentation of color Doppler without documentation of spectral Doppler is not sufficient to support the assignment of a duplex code. (See Clinical Examples in Radiology, Summer 2012 & Winter 2015).
A duplex study can be reported together with a nonvascular ultrasound study of the same anatomic area – for example, 93975 with 76700 – when both services are performed and documented. (See CPT® Assistant, March 2015). According to Clinical Examples in Radiology (Summer 2012), performance of the duplex study falls under the “test design” exception to the Medicare ordering rules and therefore does not require an order from the treating physician. However, all payers may not agree with this interpretation, so it is important to review payer policy.
Imaging facilities should not routinely add duplex to every ultrasound exam. If there is not an order for the duplex, there must be “a detailed explanation by the radiologist in his or her report as to why the Doppler was medically necessary.” (See Clinical Examples in Radiology, Winter 2013).
When ultrasound and duplex are performed together, both studies must be medically necessary, and both must meet the requirements for the CPT® code in terms of technique and structures visualized. The radiologist should dictate separate reports for the two studies or – at a minimum – describe the studies under separate headings in the same report.
The Correct Coding Initiative (CCI) edits bundle many nonvascular ultrasound codes into the duplex study code for the same anatomic area. Modifier 59 or modifier XU may be applied to the nonvascular ultrasound code when a complete, separate, medically necessary study is documented. For example, a physician orders a complete abdominal ultrasound and a complete duplex scan of the hepatic and portal vessels for a patient with portal hypertension. Two complete exams are performed, and the radiologist dictates two separate interpretations. Report code 93975 for the complete duplex exam of the liver and 76700-59 for the complete abdominal ultrasound.
Melody W. Mulaik, MSHS, CRA, RCC, RCC-IR, CPC, COC, FAHRA, is the president of Revenue Cycle and Coding Strategies Inc.