ACR Radiology Coding Source™ January-February 2007

The introductory language in the noninvasive vascular diagnostic section of the CPT code book distinguishes between the noninvasive vascular diagnostic studies performed on the ultrasound duplex scanner from physiologic studies not performed on the duplex scanner and which do not involve imaging. Both types of noninvasive vascular diagnostic studies will be discussed to help coders better understand how to code through an enhanced technical understanding of these studies.

Conventional ultrasound (described by CPT codes in the 7xxxx series) refers to the use of high frequency sound waves which reflect off structures within the body. Real-time ultrasound is a 2-D scan that depicts structure and motion over time—like a “movie.”

Doppler ultrasound uses reflected sound waves to evaluate blood as it flows through a blood vessel. The sound waves bounce off blood cells in a motion that causes a change in the pitch of the sound, called the Doppler effect. If there is no blood flow, the pitch does not change.

Duplex ultrasound combines Doppler and conventional ultrasound, allowing the radiologist to see the structure of blood vessels, how the blood is flowing through the vessels, and whether there is any obstruction in the vessels. Color Doppler produces a picture of the blood vessel, and a computer converts the Doppler sounds into colors overlaid on the image, representing information about the speed and direction of blood flow. Using spectral Doppler analysis¹, the duplex scan images provide anatomic and hemodynamic information, identifying the presence of any stenosis or plaque in the vessels.

Physiologic studies consist of functional measurement procedures, including ankle/brachial index measurement (ABI), blood pressure (BP) and physiologic waveforms, segmental pressure measurement, plethysmography, and stress testing. These studies do not involve imaging. The most common is the ABI test, which uses a Doppler stethoscope to measure sound within the vessels at the ankle or elbow. Doppler velocity signals, called waveforms, can be measured to localize vascular disease. These can be measured at a single level, or at segmental (various) limb levels. Exercise testing can be used to analyze the functional significance of vascular disease by reassessing the blood pressure with the Doppler stethoscope after completion of an appropriate amount of stress testing. Plethysmography is a measurement of the volume of an organ or limb section, or flow rate, in response to the inflation and deflation of a BP cuff. Transcutaneous oxygen tension measurement may be done in any area of interest, usually the foot or calf. It measures the influx of blood that provides oxygen for diffusion to the skin.

In coding for noninvasive vascular studies, it is important to remember that the use of a simple hand-held or other Doppler device that does not produce hard copy output, or that produces a record that does not permit analysis of bidirectional vascular flow, is considered to be part of the physical examination of the vascular system, and is not reported separately.²

Coding Noninvasive Vascular Studies

CPT codes are divided into sections for cerebrovascular arteries (93875-93888), extremity arteries (93922-93931), extremity veins (93965-93971), visceral arterial inflow and venous outflow (93975-93981), and one code for hemodialysis access scanning (93990).

When coding duplex studies, it is important to remember that real-time and spectral Doppler images are included. Color Doppler, when used only for structure identification, does not indicate that a duplex study CPT code should be used.³

A few questions commonly occur when coding for noninvasive vascular scans of the extremities. If a limited bilateral study is performed, the code used should be the “unilateral or limited study” codes (93926, 93931, 93971). These codes are not just for a unilateral, or limited unilateral study, but encompass a bilateral study, which is otherwise limited, as opposed to complete.⁴ The physiologic study codes state “upper or lower extremity,” making it appropriate, when both upper and lower extremities are studied, to report the code twice.⁵

Duplex scans and physiologic vascular measurements may be performed in conjunction with each other, or separately—one without the other. The word “duplex” indicates that imaging was performed. Coding separately for each type of study is appropriate whenever both are performed. When coding for a physiologic study, it is not necessary to have performed all of the services listed in the parentheses (eg) section to report the code.⁶

Duplex scanning of arterial inflow/venous outflow of abdominal, pelvic, or retroperitoneal organs may be coded with CPT code 93975, or with CPT code 93976, depending on whether a complete or limited study is performed.⁷ Report the duplex scan in addition to the CPT code for the abdominal, pelvic, or retroperitoneal real time ultrasound study, when both are ordered by the referring physician due to medical necessity, and both studies are performed and documented (check for CCI edits on these code combinations). It is important to remember that the duplex study represented by codes 93975/93976 should not be coded when a quick look with color Doppler is done to check whether flow is present or for structure identification. Documentation of the assessment of flow with color, recording a spectral waveform, and a report of the findings should all be present to assign codes 93975/93976. It is the consensus of the ACR's Economics Committee on Coding and Nomenclature and the ACR's Economics Committee of the Commission on Ultrasound that these codes should only be used when medically necessary, appropriately documented, and when both spectral and color Doppler are performed.⁸

For detailed questions and answers on coding duplex Doppler studies of specific organs, refer to that section in the 2006 ACR Ultrasound Coding User's Guide.

¹ Spectral Doppler: The distribution of the amplitude (and sometimes phase) of the components of the wave as a function of frequency, and the set of frequencies, wavelengths, or related quantities involved in an ultrasonic pulse or electronic signal. Definition from the 2006 ACR Ultrasound Coding User's Guide.

² CPT 2007 Professional Edition

³ 2006 ACR Ultrasound Coding User's Guide, p.21

⁴ CPT Assistant, March 2003, p.21

⁵ CPT Assistant, June 2001, p.10

⁶ CPT Assistant, December 1997, p.10

⁷ CPT Assistant, April 1996, p.11

⁸ 2006 ACR Ultrasound Coding User's Guide, p.10