93978

Duplex scan of aorta, inferior vena cava, iliac vasculature, or bypass grafts; complete study

The procedure represented by CPT code 93978 is a comprehensive, non-invasive diagnostic ultrasound evaluation of the major abdominal and pelvic blood vessels. This complete duplex scan assesses the abdominal aorta, inferior vena cava (IVC), bilateral iliac vasculature (both arteries and veins), or associated surgically placed bypass grafts. The term duplex signifies the combined use of two ultrasound modalities: conventional B-mode (real-time grayscale imaging) to visualize the anatomic structure of the vessels, and Doppler ultrasound (including color flow and spectral Doppler) to evaluate the hemodynamic characteristics of blood flow. During the examination, the physician or technologist systematically evaluates these vessels for pathological conditions such as abdominal aortic aneurysms (AAA), atherosclerotic plaque, stenosis, thromboembolic events (such as deep vein thrombosis in the IVC or iliac veins), and venous insufficiency. Additionally, it is heavily utilized for the post-operative surveillance of aortic, aortoiliac, or iliofemoral bypass grafts to ensure patency and detect complications like pseudoaneurysms, hematomas, or anastomotic stenosis. A complete study dictates a thorough bilateral assessment (where applicable, such as the iliacs) and an exhaustive examination of the aorta and IVC throughout their entire accessible abdominal courses. The provider measures vessel diameters to screen for or monitor aneurysms and records spectral Doppler waveforms to identify peak systolic velocities, which are critical for grading the severity of any arterial stenosis. This non-radiation, contrast-free imaging modality is crucial for guiding the medical, endovascular, or surgical management of vascular diseases. The clinical utility extends to evaluating endovascular aortic repair (EVAR) for the presence of endoleaks, mapping the vascular anatomy prior to complex pelvic surgeries, and identifying the source of unexplained lower extremity claudication or suspected Leriche syndrome. Furthermore, the combination of real-time imaging and physiologic flow data allows for a highly accurate diagnostic yield without the nephrotoxic risks associated with contrast-enhanced CT or MR angiography. Complete documentation, including permanently recorded images and a formal written interpretive report detailing both the morphologic findings and the hemodynamic parameters, is required to meet the standards of this complete procedure code.

Clinical Indications

  • Screening, surveillance, or diagnosis of abdominal aortic aneurysm (AAA).
  • Evaluation of a palpable, pulsatile abdominal mass.
  • Suspected aortoiliac occlusive disease (e.g., Leriche syndrome).
  • Suspected deep vein thrombosis (DVT) extending into the iliac veins or inferior vena cava.
  • Post-surgical follow-up and surveillance for aortic, aortoiliac, or iliac artery bypass grafts.
  • Assessment of endovascular aortic aneurysm repair (EVAR) to detect endoleaks or graft migration.
  • Evaluation of unexplained lower extremity claudication when peripheral pulses are diminished and pelvic vascular inflow disease is suspected.

Procedure Steps

  1. The patient is typically instructed to fast for 6 to 8 hours prior to the exam to minimize bowel gas, which can obscure ultrasound visualization.
  2. The patient is positioned supine on the examination table.
  3. Acoustic coupling gel is applied to the patient's abdomen and pelvic regions.
  4. A low-frequency ultrasound transducer is placed on the abdomen to begin the scan.
  5. B-mode grayscale imaging is utilized to visually assess the abdominal aorta, IVC, and bilateral common, internal, and external iliac vessels in multiple planes (longitudinal and transverse).
  6. Vessel diameters are meticulously measured, specifically targeting any aneurysmal dilation or ectasia in the aorta or iliac arteries.
  7. Color flow Doppler is activated to observe blood flow direction, patency, and to detect areas of flow disturbance, aliasing, or thrombosis.
  8. Spectral Doppler waveforms are obtained and recorded at various intervals to measure peak systolic and end-diastolic velocities, assessing overall hemodynamics.
  9. The transducer is manipulated to trace the entire accessible length of the native vessels or surgically placed bypass grafts.
  10. The gel is wiped off the patient, and the recorded images, diameter measurements, and hemodynamic data are compiled into a final interpretive report.

Coding Guidelines

  • CPT 93978 must be used only for a complete study, meaning the provider evaluated the full required anatomic scope including the aorta, IVC, and bilateral iliac vasculature or their corresponding bypass grafts.
  • If only a single vessel segment is evaluated, or the study is limited/unilateral, CPT 93979 (limited study) must be reported instead.
  • Do not report 93978 in conjunction with 93979 for the same patient encounter.
  • Append modifier 26 for the professional component (interpretation and report) if the equipment is not owned by the provider.
  • Append modifier TC if only the technical component (the physical performance of the scan) is provided.
  • The medical record must include permanently recorded images and a formal written report containing both anatomic and hemodynamic findings to substantiate billing.
  • Do not bill 93978 for a dedicated Medicare AAA screening if the payer specifically requires the use of HCPCS code G0389 for that indication.

Associated ICD-10 Codes