CPT code 93975 describes a complete duplex scan of the arterial inflow and venous outflow of abdominal, pelvic, or retroperitoneal organs. In practical terms, it is the billing code used when a sonographer performs a thorough vascular ultrasound of your abdomen or pelvis, combining standard grayscale imaging with Doppler technology to assess how blood is moving through the vessels that supply and drain organs like the liver, kidneys, spleen, and intestines. The “complete” designation matters because it distinguishes 93975 from its companion code, 93976, which covers a limited study of fewer vascular territories.
What the Code Actually Covers
CPT 93975 is built around two imaging techniques used together. The first is B-mode (grayscale) ultrasound, which creates a real-time picture of the vessel walls and surrounding tissue. The second is Doppler ultrasound, which measures the speed and direction of blood flow. When these are combined, the exam is called a “duplex” scan. Color Doppler adds a visual map of flow direction and velocity overlaid on the grayscale image, while spectral Doppler produces waveform tracings that let the interpreting physician judge whether flow patterns are normal or disturbed.
For the exam to qualify as “complete” under 93975, the sonographer evaluates both the arteries feeding and the veins draining the relevant organs. A scan that looks at only one side of that equation, say just the arterial supply to a kidney transplant, would typically fall under the limited code 93976 instead. The distinction is important mainly for billing and documentation, but it also signals the depth of the examination your physician ordered.
The organs and vascular beds that fall under this code span a wide territory. The most common targets include the renal arteries and veins, the hepatic (liver) vasculature and portal venous system, the mesenteric arteries supplying the intestines, and the aorta and iliac arteries running through the abdomen and pelvis. Pelvic veins and transplant organ vasculature also fall within its scope.
Why Your Doctor Might Order This Exam
Physicians request a 93975 study when they need to understand blood flow through abdominal or pelvic organs without resorting to invasive procedures or imaging that involves radiation. The specific clinical reason varies depending on which vascular bed is being examined.
Kidney Blood Supply
One of the most common reasons for this exam is to screen for renal artery stenosis, a narrowing of the arteries feeding the kidneys. This condition can drive high blood pressure that does not respond well to medication and, in some cases, contributes to kidney damage. Color Doppler ultrasound is considered a reliable, noninvasive way to screen for renovascular disease when performed by an experienced sonographer.1PubMed Central. Doppler ultrasound and renal artery stenosis: An overview Renal artery duplex scanning is also used to help classify patients with heart failure who may have underlying renal artery narrowing, since that combination can worsen outcomes during hospitalization.2The American Journal of the Medical Sciences. Impact of renal artery stenosis on acute kidney injury and outcomes after heart failure hospitalization
Liver and Portal Vein
In patients with chronic liver disease or cirrhosis, Doppler ultrasound of the hepatic vasculature is a core part of the workup. The exam can reveal characteristic changes in blood flow through the portal vein, hepatic artery, and hepatic veins that signal worsening liver disease or rising pressure in the portal venous system.3PubMed Central. Altered Doppler flow patterns in cirrhosis patients: an overview Detecting reversed (hepatofugal) flow in the portal vein is particularly significant because it helps confirm portal hypertension and can influence treatment decisions, including evaluating whether a portosystemic shunt is working.4PubMed. Hepatofugal flow in the portal venous system: pathophysiology, imaging findings, and diagnostic pitfalls
Mesenteric Arteries and Intestinal Blood Flow
The mesenteric arteries, particularly the superior mesenteric artery and the celiac artery, supply blood to the intestines. Duplex scanning of these vessels is used primarily to identify high-grade narrowing that can cause chronic mesenteric ischemia, a condition where the gut does not get enough blood flow, especially after eating.5PubMed. Mesenteric duplex scanning Color Doppler has been shown to be a valid first-line imaging tool for evaluating mesenteric blood flow, and it can sometimes pick up localized flow disturbances that CT or MR angiography misses.6PubMed Central. Color Duplex evaluation of the mesenteric artery Accurate diagnosis depends heavily on the sonographer’s expertise and familiarity with mesenteric anatomy.7PubMed. The radiologist’s guide to duplex ultrasound assessment of chronic mesenteric ischemia
Aorta and Post-Surgical Monitoring
The abdominal aorta is another frequent target. For patients who have had an endovascular aneurysm repair (EVAR), where a stent graft is placed inside an aortic aneurysm, duplex ultrasound is used during follow-up to measure the aneurysm sac and check for endoleaks, which are persistent blood flow around or through the graft. A standardized duplex protocol for this includes imaging the graft in multiple planes and using color Doppler to look for any leak around the device.8Journal of Vascular Surgery. Duplex ultrasound scanning versus computed tomographic angiography for postoperative evaluation of endovascular abdominal aortic aneurysm repair
Transplanted Organs
After a kidney or liver transplant, the vascular connections to the new organ need regular monitoring. Grayscale ultrasound combined with color and spectral Doppler is the standard approach for checking that the blood vessels feeding and draining a transplant are open and functioning.9PubMed Central. Contrast-enhanced ultrasound of transplant organs – liver and kidney – in children Specific waveform patterns help clinicians identify complications like arterial thrombosis, venous stenosis, or rejection early, often guiding treatment decisions without the need for biopsy.10Ultrasound Clinics. Transplant Ultrasound of the Kidney, Liver, and Pancreas
Pelvic Vasculature
In the pelvis, duplex ultrasound can evaluate conditions like pelvic congestion syndrome, where varicose veins develop around the ovaries and uterus, and compression syndromes such as May-Thurner syndrome, where the left common iliac vein is squeezed by the overlying artery. In one study comparing duplex ultrasound to MR venography for diagnosing these conditions, duplex was able to clearly visualize the left renal vein (for nutcracker anatomy) about 89% of the time and the left common iliac vein (for May-Thurner anatomy) about 93% of the time, performing comparably to or slightly better than MR venography.11Journal for Vascular Ultrasound. A Study Comparing the Results of Duplex Ultrasound and Magnetic Resonance Venography to Diagnose Pelvic Vein Congestion in Conjunction with a Compression Syndrome Duplex ultrasound is often part of the diagnostic workup alongside CT or conventional venography before any intervention is planned.12PubMed. Endovascular interventions in the treatment of pelvic congestion syndrome caused by May-Thurner syndrome
What to Expect Before and During the Exam
If your 93975 study focuses on abdominal organs, you will usually be asked to fast for several hours beforehand. The typical instruction is nothing to eat or drink for six to eight hours before the appointment. The reason is straightforward: food in the stomach and gas in the intestines can obscure the ultrasound view of the vessels underneath.13PubMed Central. Pitfalls in ultrasound imaging of the stomach and the intestines That said, the benefit of fasting is not universal. A randomized trial found that fasting did not produce a statistically significant improvement in overall abdominal imaging quality, though it did help with gallbladder visualization and with imaging quality in male patients specifically.14PubMed. To eat or not to eat? Effect of fasting prior to abdominal sonography examinations on the quality of imaging under routine conditions: A randomized, examiner-blinded trial Despite that nuance, most labs still default to fasting instructions because the potential improvement in image quality is worth the inconvenience.
During the exam itself, you lie on an examination table while a sonographer applies gel and moves a transducer across your abdomen or pelvis. The sonographer will press firmly at times to get the transducer closer to deep vessels. They may ask you to hold your breath, roll onto your side, or take deep breaths to shift organs into better view. The study can take anywhere from 30 minutes to over an hour, depending on how many vascular beds need evaluation and how cooperative your body habitus and bowel gas are on that particular day.
How the Results Are Read
After the images are acquired, a physician (usually a radiologist or a vascular medicine specialist) interprets the study. The key diagnostic information comes from the spectral Doppler waveforms. Each vessel in the abdomen has a characteristic “signature” waveform shape when blood flow is normal. The arteries supplying organs with constant metabolic demand, like the kidneys, typically show continuous forward flow throughout the cardiac cycle. Arteries feeding the gut may show higher resistance when fasting and lower resistance after a meal. Veins have their own patterns influenced by breathing and heart function.
Abnormalities show up as distortions of these waveforms. A significant narrowing in an artery causes the peak flow velocity to spike at the stenosis and dampens the waveform downstream. Complete blockage eliminates the signal. Reversed flow in a vein, as with hepatofugal portal flow in cirrhosis, immediately signals something pathological. Analysis of these waveforms, alongside the B-mode and color Doppler images, allows the interpreting physician to characterize the location and severity of disease.15Journal for Vascular Ultrasound. Characterization of Blood Flow Patterns in the Hepatoportal, Mesenteric, and Renal Vessels by Analysis of Doppler Spectral Waveforms Specific velocity thresholds are used for different vessels. For instance, celiac artery compression syndrome in younger patients can be diagnosed when the peak systolic velocity in the celiac artery exceeds 200 cm/s or is more than double the velocity in the nearby aorta, with changes during breathing.16PubMed. Celiac artery compression syndrome in children, adolescents, and young adults: clinical and color duplex sonographic features in a series of 59 cases
Limitations Worth Knowing About
Duplex ultrasound is not perfect, and the quality of a 93975 study can vary significantly based on patient and operator factors. Body size is one of the biggest challenges. Ultrasound waves lose energy as they travel through tissue, and the deeper the vessel, the harder it is to image. Research has shown that imaging quality of the liver and kidney vasculature drops as body mass index increases, with BMI being the strongest predictor of image quality in one study, explaining a large portion of the variability in ultrasound scores.17PubMed Central. The application of high-performance ultrasound probes increases anatomic depiction in obese patients Higher-performance transducers help somewhat in patients with a BMI above 35, but the physics of sound attenuation through tissue cannot be fully overcome.
Bowel gas is another persistent obstacle. Loops of intestine filled with air scatter ultrasound waves and create acoustic shadows that can hide the mesenteric vessels, the aorta, or the renal arteries. This is one reason the fasting preparation exists, even if its benefits are modest on average. In some patients, no amount of preparation or technique will yield diagnostic images of certain vessels, and the interpreting physician will note those territories as “not adequately visualized” in the report.
Operator dependence is the third major limitation. Unlike CT or MRI, where the images are acquired according to a relatively standardized protocol and can be reviewed afterward by anyone, ultrasound is heavily dependent on the skill of the person holding the transducer. A less experienced sonographer may miss a subtle stenosis or fail to optimize the Doppler settings for a deep vessel. This is why many of the clinical studies on duplex ultrasound performance emphasize that results depend on expert operators.
How Duplex Ultrasound Compares to CT and MRI
For many of the conditions evaluated under 93975, CT angiography and MR angiography are the main alternative imaging options. Each has trade-offs. CT angiography provides excellent spatial resolution and is less operator-dependent, but it involves ionizing radiation and iodinated contrast dye, which can be toxic to the kidneys. MR angiography avoids radiation but is more expensive, takes longer, and is not suitable for patients with certain implants.
The comparison has been studied most thoroughly for aortic aneurysm surveillance after stent graft repair. Multiple prospective studies have found that contrast-enhanced ultrasound is as accurate as CT angiography for measuring aneurysm sac diameter, with measurements agreeing closely between the two modalities.18PubMed. Contrast-enhanced ultrasound vs. CT angiography in fenestrated EVAR surveillance: a single-center comparison One study found ultrasound actually detected more endoleaks than CT angiography, predominantly small type II leaks, leading to relatively low agreement between the two methods on endoleak presence.19PubMed. Contrast-enhanced ultrasound versus computed tomographic angiography for surveillance of endovascular abdominal aortic aneurysm repair Another single-center comparison confirmed that contrast-enhanced ultrasound matches CT angiography for endoleak detection and diameter measurement, without carrying the risks of radiation exposure or kidney-damaging contrast.20PubMed. Single-centre prospective comparison between contrast-enhanced ultrasound and computed tomography angiography after EVAR
These findings have led some centers to adopt ultrasound-based surveillance as a partial substitute for CT angiography in post-EVAR follow-up, particularly for patients who need annual imaging for years and would otherwise accumulate a significant lifetime radiation dose. The standard (non-contrast) duplex exam billed under 93975 remains the most commonly used version, though contrast-enhanced studies are increasingly available.
Contrast-Enhanced Ultrasound and Emerging Techniques
Standard duplex ultrasound, as described by CPT 93975, relies on the patient’s own blood cells to generate Doppler signals. Contrast-enhanced ultrasound (CEUS) adds an intravenous injection of microbubble contrast agents, which are tiny gas-filled spheres that dramatically increase the echogenicity of blood. This enhancement allows real-time, high-resolution visualization of blood flow down to the microvascular level, well beyond what standard Doppler can show.21Journal of Vascular Surgery Cases, Innovations and Techniques. Clinical applications of contrast-enhanced ultrasound in vascular surgery: State-of-the-art narrative and pictorial review
CEUS has established applications in evaluating carotid artery disease, post-intervention follow-up of aortic aneurysms, and assessing portal vein thrombosis in liver disease.22PubMed Central. General principles and overview of vascular contrast-enhanced ultrasonography The microbubble agents used are generally safe, carry no risk to the kidneys (unlike iodinated CT contrast), and are cleared through the lungs within minutes. CEUS is typically billed under different CPT codes than 93975, but the underlying duplex exam often serves as the foundation that a contrast study builds upon. If your physician wants to evaluate something beyond what standard Doppler can answer, particularly subtle endoleaks or microvascular perfusion in a transplanted organ, adding contrast is an option that is becoming more widely available.
Pediatric and Young Adult Uses
While most 93975 exams are performed on adults, the code applies equally to pediatric patients. Children and young adults undergo abdominal vascular duplex scanning for some of the same reasons as older patients, but a few conditions are more characteristic of younger populations. Celiac artery compression syndrome (also called median arcuate ligament syndrome) is one example. It occurs when a fibrous band compresses the celiac artery, restricting blood flow to the stomach and upper intestines. Color duplex ultrasound is the primary tool for diagnosing this condition in children and adolescents, using velocity thresholds and changes with breathing to confirm the compression.16PubMed. Celiac artery compression syndrome in children, adolescents, and young adults: clinical and color duplex sonographic features in a series of 59 cases
Pediatric transplant recipients also undergo regular duplex surveillance of liver or kidney grafts. The absence of radiation makes ultrasound particularly attractive in children, who are more sensitive to cumulative radiation exposure than adults. Duplex ultrasound combined with Doppler techniques remains the standard first-line approach for monitoring transplant vasculature in this population.9PubMed Central. Contrast-enhanced ultrasound of transplant organs – liver and kidney – in children For pediatric patients with suspected vascular anomalies, portal hypertension from congenital liver conditions, or renovascular hypertension, the 93975 exam provides a safe, repeatable way to evaluate blood flow without sedation in most cases, since the exam requires only cooperation with breathing instructions rather than the prolonged stillness needed for MRI.