Analytic and Clinical Validity
Gale et al evaluated waveform analysis with and without segmental pressures in eighty-one patients against arteriography.16 The standalone waveform analysis yielded an accuracy of 64–83% across arterial segments. When ABI was added, accuracy improved significantly across all segments (e.g., from 64% to 70% at the popliteal level, P<0.01), indicating that ABI enhances analytic validity. However, segmental pressures beyond the ankle were not found to further improve diagnostic performance.
Polak et al reported that color-assisted duplex sonography achieved a sensitivity of 88%, specificity of 95%, and overall accuracy of 93% in detecting stenosis or occlusion in femoropopliteal arteries, suggesting high analytic validity in a clinical setting.23 The twenty-nine-minute bilateral scan time also supports its utility for rapid preoperative triage.
Mestre et al demonstrated that CEUS resolved limitations of standard ultrasound in nearly half of eighty-six patients with CLTI who had inconclusive non-enhanced exams performed for surgical planning.17 CEUS altered surgical plans in 53.5% of these cases, improving agreement between imaging and surgical findings to 95.2% (k=0.823, P=0.00001). The study also found that basic ultrasound was sufficient in 85% of five hundred sixty-five CLTI patients. Even among those needing CEUS, only a marginal portion of participants (5.8%) required further arteriography.
Chuter et al found moderate diagnostic performance of DUS, with good specificity but variable sensitivity.9 They analyzed thirty-three studies and performed a Summary Receiver Operating Characteristic analysis, using angiography as the reference standard, which found a diagnostic odds ratio (DOR) of 9.06 [95% confidence interval (CI): 3.61-22.69], and area under the curve (AUC) of 0.76 (95% CI: 0.66-0.86). Bivariate analysis of the studies using DUS demonstrated mean sensitivity of 0.60 (95% CI: 0.48-0.71; P=0.097) and mean specificity of 0.87 (95% CI: 0.78-0.92; P<0.001) with a DOR of 9.76 (95% CI: 5.24-18.20; P<0.0001) and AUC 0.72. The strength of the correlation between sensitivity and specificity was moderate (r=−0.435). Global measures of diagnostic accuracy were indicative of good test performance.
A systematic review by Collins found duplex ultrasonography had a median sensitivity of 88% (range 80–98%) and specificity of 96% (89–99%) for detecting ≥50% stenosis, close to, but slightly lower than CE-MRA (sensitivity 95%, specificity 97%).20 Despite these differences, the diagnostic performance of DUS was considered sufficient for treatment planning in most cases, suggesting that the difference in accuracy was not clinically meaningful.
Another systematic review and meta-analysis, from deSouza et al, evaluated the accuracy of various methods of diagnosing arterial injury following penetrating extremity trauma.10 They used the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS-2) to evaluate bias and applicability of identified studies and calculated positive and negative likelihood ratios (LR+ and LR–, respectively) of physical examination, DUS, and ABI. The authors found that the majority of studies included had a low risk of bias and low concerns regarding their applicability. They found that DUS had a positive likelihood ratio (LR+) of 35.4 (95% CI: 8.3–151) and a negative likelihood ratio (LR–) of 0.24 (95% CI: 0.08–0.72), with a weighted prevalence of arterial injury of 18.9%. Based on these values, a positive DUS increased the post-test probability of arterial injury to 89%, well above the commonly cited threshold (72.9%) for proceeding directly to treatment or CTA. A negative DUS result reduced the post-test probability to 5%, still above the 0.14% testing threshold for CTA. However, when both the physical examination (absence of hard or soft signs) and ABI were normal, the LR– dropped to 0.01 (95% CI: 0.0–0.10), effectively lowering the post-test probability to 0%. These findings suggest that while normal physical exam and ABI together may be sufficient to rule out arterial injury in low-risk patients, DUS offers valuable diagnostic accuracy, particularly when either clinical signs or ABI are abnormal, and plays a critical role in guiding next steps in management.
Williams et al found that the sensitivity and specificity of ABI and foot pulses were substantially reduced in patients with diabetes and peripheral neuropathy.19 In contrast, the TBI and qualitative doppler waveform analysis performed better. Although the study did not evaluate full DUS, it highlights the limitations of relying on pulses or ABI alone in this high-risk group and supports the use of alternative modalities like TBI or doppler when neuropathy is present. For example, ABI sensitivity dropped from 71% to 38% in neuropathic limbs, while waveform analysis remained more reliable. Given the high prevalence of neuropathy among diabetic patients, this represents a significant limitation of ABI and supports the use of alternative techniques such as DUS.
Clinical Utility
Guidelines from the Society of Vascular Surgery, the American College of Cardiology and American Heart Association, and the French Society of Vascular Medicine, and the French Society for Vascular and Endovascular Surgery, consistently recommend DUS in both diagnostic and monitoring roles.2-5,8 For symptomatic patients or those being considered for revascularization, DUS is recommended alongside ABI testing. It is also recommended in preoperative vein mapping, particularly in bypass planning, and in routine surveillance following interventions, especially within the first year and annually thereafter.
The ACC/AHA 2024 PAD Guideline, emphasizes the importance of physiological testing (ABI, toe pressures) for diagnosis, and notes that anatomic imaging (DUS, CTA, MRA, or angiography) is indicated when intervention is contemplated.2 DUS is included as one of the recommended modalities for planning revascularization or investigating atypical symptoms. In these patients, the pre-test probability of disease is high, and DUS findings are likely to yield actionable information (e.g. identifying a femoral artery occlusion that could be stented).
The Society of Vascular Surgery, Sobieszczyk et al, and Venermo et al provide structured timelines for DUS surveillance post repair of PAAs and vein grafts.4,11,12 The Society of Vascular Surgery also recommends follow-up with clinical examination including ABI and DUS at 3, 6, and 12 months during the post-operative year and annual DUS after.4 Venermo et al, is an evidence-based consensus document describing surveillance techniques post-revascularization, which outline that DUS should be conducted at 1, 3, 6, and 12 months and then yearly thereafter.12 Sobieszczyk et al, a narrative review describing the use of DUS post-intervention, states that surveillance should occur at 1, 6, and 12 months and then annually thereafter following interventions in the aortoiliac arterial segment, femoropopliteal arterial segment, and tibial arteries.11
DUS was also found to be reliable in surgical planning and surveillance. Ligush et al, Mofidi et al, Mestre et al, and Tielbeek et al reported high agreement between DUS and operative findings and found that DUS effectively identified lesions that influenced surgical decisions.17,24-26 Similarly, Stone et al observed that early DUS-detected graft stenosis was predictive of outcomes and influenced reintervention timing and long-term patency.27,28
Collins et al reported that DUS alone was sufficient to guide treatment plans in most patients with lower limb PAD and that outcomes did not differ significantly between those whose plans were based on DUS versus contrast angiography, though 22% of patients still required supplementary imaging.20 While patients preferred MRA for comfort and safety, there was no clear patient preference between duplex ultrasound and angiography, indicating general acceptability.
Other studies also highlight the importance of timely and appropriate vascular testing in patients at risk for PAD. Varghese et al found that most patients undergoing major lower extremity amputations had evidence of severe atherosclerosis on pathology, yet fewer than 60% received vascular diagnostic evaluation, such as DUS, in the year prior.29 This suggests missed opportunities for limb salvage through earlier identification and treatment of disease. Sebastianski et al further demonstrated that patients with PAD were at risk of more complex CAD and worse outcomes after revascularization, reinforcing the need for accurate identification of PAD.30 Similarly, Lijmer et al found that while ABI is generally accurate for detecting proximal disease, additional testing, such as doppler waveform analysis, is needed to assess more complex or distal disease.31
Studies from Polak et al, Saarinen et al, and Lane et al further affirm DUS’s diagnostic accuracy and feasibility in post-operative monitoring.23,32,33 Stone et al and Mofidi et al also noted that DUS-guided intervention correlated with improved limb salvage and patency.25,27 DUS is not universally preferred. Guidelines from the American College of Radiology categorize it as “may be appropriate” in some scenarios, noting limitations in vessel accessibility and lower sensitivity compared to CTA, particularly in acute limb ischemia (ALI).7 Guidelines form the American College of Cardiology and American Heart Association also recommend CTA or MRA when evaluating complex or distal disease or when DUS yields inconclusive results.2
The guidelines from the American College of Cardiology and American Heart Association, published in 2024, in collaboration with nine additional organizations, ranked recommendations as Strong, Moderate, Weak, No Benefit, and Strong likelihood of harm; with evidence levels of A (high quality), B-R (moderate, randomized), B-N (moderate, non-randomized), C-LD (limited data), and C-EO (expert opinion).2 Their recommendations regarding ultrasounds were:
- In patients with functionally limiting claudication with inadequate response to guideline-directed management and therapy (including structured exercise) for whom revascularization is being considered, DUS, CTA, MRA, or catheter angiography of the lower extremities is useful for assessment of anatomy and severity of disease and to determine potential revascularization strategy (Strong, B-NR)
- In patients with CLTI, DUS, CTA, MRA, or catheter angiography is useful to determine revascularization strategy (Strong, B-NR)
- In patients with suspected PAD (e.g., potential signs and/or symptoms) with inconclusive ABI and physiological testing, noninvasive imaging with DUS, CTA, or MRA may be considered to establish the diagnosis of PAD (Weak, C-EO)
- In patients with a confirmed diagnosis of PAD in whom revascularization is not being considered, CTA, MRA, or catheter angiography should NOT be performed solely for anatomic assessment (Strong likelihood of harm, B-NR)
- In patients with CLTI who are candidates for surgical bypass or endovascular revascularization, preoperative ultrasound mapping of the great saphenous vein is recommended (Strong, B-R)
- In patients with ALI who have a complicated history of revascularization procedures, it may be reasonable to obtain noninvasive imaging (i.e., DUS, CTA, or MRA) before deciding to proceed with revascularization (Weak, C-EO)
- In patients with PAD who have undergone lower extremity revascularization (i.e., surgical, endovascular, or both) with new lower extremity signs or symptoms, ABI and arterial DUS is recommended (Strong, C-LD)
- In patients with PAD who have undergone infrainguinal, autogenous vein bypass graft(s) without new lower extremity signs or symptoms, it is reasonable to perform ABI and arterial DUS surveillance within the first 1 to 3 months post-procedure, then repeat at 6 and 12 months, and then annually (Moderate, B-R)
- In patients with PAD who have undergone endovascular procedures without new lower extremity signs or symptoms, it is reasonable to perform ABI and arterial DUS surveillance within the first 1 to 3 months post-procedure, then repeat at 6 and 12 months, and then annually (Moderate, C-LD)
- In patients with PAD who have undergone infrainguinal, prosthetic bypass graft(s) without new lower extremity signs or symptoms, the effectiveness of ABI and arterial DUS surveillance is uncertain (Weak, B-NR)
A systematic review and a meta-analysis, Hoitz et al and McKenna et al, found that DUS surveillance post-intervention improves graft patency and reduces amputation rates, outperforming clinical exam or ABI follow-up alone.34,35 Hoitz was a systematic review that assessed 5 studies and found a moderate certainty level of evidence to suggest a benefit of DUS surveillance compared with standard clinical surveillance. The DUS group demonstrated improved primary assisted patency (84% versus 76% at 12 months and 68% versus 38% at 36 months, P=0.008) and limb salvage (97% versus 83% at 12 months and 90% versus 50% at 36 months, P<0.001) compared with ABI follow-up. In 1 single-armed study, DUS surveillance showed a high sensitivity (91%) and specificity (100%) in detecting restenosis. ABI and clinical follow-up demonstrated a low sensitivity (55-67% and 52-64%, respectively) but reasonable specificity (80-85% and 82-88%, respectively) in detecting restenosis. McKenna only identified 2 studies which met their inclusion criteria but found that the combined surveillance group (DUS plus clinical surveillance) had significantly less likelihood of amputation than the clinical-only group at 12 months post-intervention for PAD of the lower extremities (10/275 [3.6%] vs 18/120 [15%], OR=0.22, 95% CI=0.10-0.48, I2 0). At twenty-four months 1 study reported a benefit while the other didn't. Meta-analyses identified a benefit but there was significant heterogeneity (I2 85%), OR=0.25, 95% CI:0.04-1.58. Only 1 study reported on primary-assisted patency which reported 12-, 24-, and 36-month rates of primary-assisted patency of 84%, 75%, and 68%, respectively, in the combined group versus 76%, 51%, and 38% in the clinical-only group. One study reported 12-, 24-, and 36-month mortality rates of 8%, 14%, and 16%, respectively, in the combined group versus 25%, 35%, and 60% in the clinical-only group. And the other study reported 90% survival after sixty months in the combined group vs 50% in the clinical-only group (P=0.017).
Sarpe et al on the other hand concluded that DUS may not improve limb salvage or patency rates in the short term but may increase reintervention and angiography rates.36 In the short term, they found that DUS surveillance led to little or no difference in limb salvage rates (risk ratio [RR] 0.84, 95% CI: 0.49-1.45; I2 93%; 2 studies, nine hundred thirty-six participants; low-certainty evidence) and vein graft secondary patency (RR 0.92, 95% CI: 0.67-1.26; I2 57%; 3 studies, one thousand ninety-two participants; low-certainty evidence). However, they also found that DUS may increase re-intervention rates when considered any therapeutic intervention (RR 1.38, 95% CI: 1.05-1.81; 3 studies, one thousand ninety-two participants; low-certainty evidence) or angiogram procedures (RR 1.53, 95% CI: 1.12-2.08; 3 studies, one thousand ninety-two participants; low-certainty evidence).
Lundell et al, the sole RCT identified, reported higher graft patency rates with intensive DUS monitoring compared to routine surveillance.37
Additional observational studies provide further evidence. Humphries et al found that abnormal early DUS after infrainguinal revascularization was associated with a higher risk of amputation and that DUS could detect residual stenoses missed by angiography.38 Hardy et al also highlight DUS’s role in preoperative assessment to guide revascularization decisions and reduce amputation rates.39 Crawford et al (2016) demonstrated that preoperative DUS was equivalent to angiography in managing peripheral arterial embolism, and Gale et al found that waveform analysis combined with ABI significantly improved diagnostic accuracy.16,40 Gardner et al showed that ABI values are reproducible across measurement methods, while Lijmer et al validated ABI’s diagnostic precision using ROC analysis.31,41
In diabetic populations, Fitridge et al and Chen et al show that combining DUS with ABI and TBI enhances PAD detection, especially in patients with normal ABI but significant disease.6,42 Babaei et al, Hur et al, and Normahani et al confirm that waveform analysis and toe pressures improve sensitivity, and that DUS offers higher diagnostic accuracy than ABI and TBI alone.13,43,44 Aubert et al found that pulse palpation combined with ABI outperformed ABI alone, and Williams et al found that DUS and TBI were more accurate than ABI in patients with neuropathy.19,45 Tsai et al and Hsu et al observed that DUS-detected femoral plaque and waveform abnormalities were predictive of limb loss in patients with chronic kidney disease (CKD).46,47
Similarly, multiple society guidelines emphasize the value of DUS for diagnosing PAD in diabetic patients and for assessing limb perfusion and healing potential in those with ulcers or gangrene.1,5,6 However, they note no single diagnostic tool is definitive, and that DUS should be part of a multimodal approach. Additionally, we found no evidence to support the use of serial testing in the absence of new or worsening symptoms indicative of arterial insufficiency, such as increased claudication or declining functional capacity.
Studies by Kovacs et al, Nattero-Chávez et al, and Vriens et al support the role of exercise testing and waveform analysis in refining diagnostic accuracy.48-50 Post-exercise indices such as TBI and tcpO2 significantly differentiated disease severity and predicted outcomes. An additional study from Corvino et al also confirmed DUS’s high sensitivity and specificity in identifying pseudoaneurysms.51
Rationale for Determination
Since only 1 non-U.S. based RCT was discovered in our search for DUS literature, coverage guidance is largely dependent on observational data, systematic reviews/meta-analyses, and evidence published in specialty society guidelines. However, based on the consistency of reported outcomes, the high level of diagnostic accuracy of mostly observational studies indicates a moderate certainty of evidence (upgraded from low certainty due to strong agreement and large effect sizes). Given the accessibility of the technology and the low risk of harm to patients, the available level of certainty provides sufficient evidence to support that limited coverage of DUS of extremity arteries is reasonable and necessary for PAD (including surgical planning and post-operative monitoring), peripheral aneurysms, and trauma-related injury.
Clinical Validity and Utility in PAD
DUS can establish PAD diagnosis, localize stenoses/occlusions, and grade severity of arterial narrowing, yielding more anatomical detail than an ABI test alone, which measures limb perfusion but not lesion location. DUS accuracy is affected by the arterial segment being imaged such that accuracy is lower in distal, below-knee vessels (e.g., sensitivity decreases below 70% for arterial segments distal to the tibial artery).
In high-risk patients (e.g., older adults, diabetics, smokers with claudication or non-healing foot wounds), DUS is a first-line imaging tool to confirm PAD and guide interventions. Multiple guidelines uniformly and strongly recommend using DUS (along with ABI) in the workup of PAD when it will affect medical management.2,14 The ACC/AHA 2024 PAD Guideline emphasizes the importance of physiological testing (ABI, toe pressures) for diagnosis and notes that anatomic imaging (duplex, CTA, MRA, or angiography) is indicated when intervention is contemplated. DUS is included as one of the recommended modalities for planning revascularization or investigating atypical symptoms. In these patients, the pre-test probability of disease is high, and DUS findings are likely to yield actionable information (e.g. identifying a femoral artery occlusion that could be stented). In low-risk individuals with leg symptoms more suggestive of musculoskeletal causes, or those with normal ABI and pulses, routine duplex scanning is usually not necessary – a normal ABI essentially rules out significant PAD in most cases. In fact, NICE and ACR advise against imaging in PAD unless it influences medical decision-making. By identifying the location and degree of stenoses, DUS guides whether angioplasty or bypass surgery is feasible, and it can target which artery segment to treat. In many cases, DUS is the first-line imaging for revascularization planning, followed by confirmatory angiography or advanced imaging, if needed. Thus, this contractor expects DUS to be used where it adds clear value (i.e., diagnosing significant disease requiring intervention or planning procedures) and not as a general screening or surveillance tool in asymptomatic, low-risk populations. DUS is repeatable and can be used post-procedure to monitor graft patency or stent results, enabling early detection of reocclusion. In fact, vascular societies endorse routine duplex surveillance/monitoring after bypass grafting to catch treatable stenoses and improve long-term patency. Therefore, coverage is limited in frequency and to specific scenarios (e.g., abnormal ABI, post-intervention etc.) where PAD exclusion is clinically useful.
Several observational studies provide additional support for this framework. Polak demonstrated high diagnostic accuracy for color-assisted DUS in detecting femoropopliteal stenoses.23 Collins found that DUS was sufficient for treatment planning in most patients with ≥50% stenosis, showing sensitivity and specificity close to that of CE-MRA.20 The use of CEUS as described by Mestre illustrates the adaptability of ultrasound in resolving inconclusive findings, altering surgical plans in over half of patients evaluated.17 In patients with diabetic neuropathy, Williams showed that TBI and qualitative waveform analysis outperformed ABI alone, underscoring the value of tailored physiologic testing.19
Evidence from systematic reviews further substantiates the utility of DUS for surveillance. Hoitz et al and McKenna et al demonstrated improved graft patency and reduced amputation rates with DUS-based follow-up compared to ABI or clinical exam alone.34,35 These findings support guideline recommendations for structured surveillance intervals following intervention.
While the body of evidence is subject to serious risk of bias due to limitations in study design (e.g., non-randomized), the large effect size and paucity of adverse risk reported by multiple studies supports a moderate to high likelihood of true benefit. Therefore, the upgraded certainty of evidence justifies limited coverage for surveillance in patients with recent interventions, such as vein bypass grafting or endovascular repair, but not in patients with stable PAD not under consideration for revascularization. Lundell, the only identified randomized trial, reinforces this by showing higher graft patency rates with intensive DUS monitoring.37
In addition, studies like Humphries et al and Hardy et al highlight how abnormal early DUS findings correlate with increased amputation risk and can inform timely reintervention.38,39 These outcomes demonstrate that DUS can impact long-term management decisions when used in targeted post-intervention settings.
Clinical Validity and Utility in Peripheral Aneurysms
DUS is widely used for both the detection and monitoring of these aneurysms in outpatient settings. In urgent care, point-of-care ultrasound can aid in the rapid identification of a suspected ruptured aneurysm. Ultrasound has a very high clinical validity for aneurysm detection.2,4 The abdominal aorta is usually easily visualized; a standard abdominal DUS can measure aortic diameter to within a few millimeters of CT scan measurements. Clinical guidelines note that aortic ultrasound is the standard technique for detecting AAA, with high diagnostic accuracy.14 In fact, screening trials have reported that ultrasound sensitivity and specificity for AAA are 95–100% when performed by trained personnel (aneurysms appear as anechoic dilations; even small AAAs >3 cm are reliably identified). For peripheral extremity aneurysms such as PAAs, DUS is also the first-line modality.2 These aneurysms are often detected on ultrasound as an enlarged arterial segment (often >1.5–2 cm for PAAs) with turbulent flow. Because popliteal aneurysms are superficial in the knee region, DUS can visualize them well. Clinical validity is high for identifying significant peripheral aneurysms or pseudoaneurysms and color doppler aids in distinguishing flowing blood from thrombus within the dilated vessel. In summary, the evidence base (including large screening studies for AAA and observational studies for peripheral aneurysms) indicates moderate certainty in DUS’s ability to accurately detect aneurysms.
In high-risk populations (e.g., men ≥65 with smoking history, or patients with a family history of AAA), one-time ultrasound screening is strongly indicated.52 These groups have a substantial prevalence of disease and proven benefit from screening. Consequently, patients with known small aneurysms (i.e. AAA or peripheral) should receive periodic ultrasound and limited coverage is granted per specialty society guideline.
Clinical Validity and Utility in Trauma
The diagnostic performance of DUS in trauma has been studied in several prospective and retrospective cohorts. A key systematic review analyzed 4 studies of DUS (one hundred seventy-three patients total) for penetrating extremity trauma.10 Authors reported that ultrasound had LR+ 35 and LR- 0.24. In practical terms, given a pre-test prevalence 19% in those studied, a positive duplex raised the post-test probability of arterial injury to 89%, while a negative duplex reduced the probability to about 5%. These figures indicate that a positive ultrasound is highly predictive of a real vascular injury, and a negative exam significantly lowers the chance of injury – though a small risk (5%) remains that could be clinically important. For context, physical exam alone for vascular injury can miss cases, and an ABI <0.9 is a known marker of arterial injury (the meta-analysis found a negative ABI had a post-test injury probability of 9%). Notably, when combined with clinical examination, the accuracy improves dramatically: patients with normal pulses and a normal ABI had essentially a 0% post-test probability of major arterial injury in the review. This implies that in very low-risk presentations, additional ultrasound may not add much – normal exam plus ABI is sufficiently reassuring. However, in cases with equivocal signs, ultrasound can clarify whether an arterial flow deficit exists. For nonatherosclerotic PAD (which covers trauma) indicates that for lower-extremity vascular trauma, CTA is “usually appropriate” as the first-line imaging. DUS is mentioned as an option but is not the preferred standalone in their summary for trauma. The ACR notes the appeal of ultrasound (portable, no contrast) but cautions that “significant injury to superficial soft tissues may limit its accuracy.”21 They cite the meta-analysis above, noting a positive ultrasound confers ~89% post-test probability of injury and a negative ~5%. The implication is that ultrasound can be used in trauma but should be reserved for specific scenarios (e.g. when CTA is contraindicated or as a preliminary exam), and if negative, one must still have a low threshold to proceed to CTA if clinical suspicion persists.
Conclusion
DUS is a low-risk, accessible, and accurate imaging modality for evaluating peripheral arteries in both the upper and lower extremities. It demonstrates moderate to high clinical validity and utility when appropriately applied across 3 key clinical scenarios: PAD, aneurysms, and nonatherosclerotic arterial conditions (e.g., trauma). Accordingly, DUS is considered reasonable and necessary for use in high-risk patient populations, particularly when guiding revascularization decisions, cardiac bypass planning, and post-procedural surveillance in accordance with clinical guidelines.
ABI and physiologic testing remain the first-line diagnostic tools for suspected PAD. However, when these tests yield inconclusive results, imaging modalities such as DUS, CTA, or MRA are recommended.
Serial DUS is strongly supported in patients presenting with signs or symptoms of arterial aneurysms and is therefore covered. In contrast, routine or annual DUS testing in patients with known PAD who are not being considered for revascularization is not supported by current specialty guidelines. As such, DUS is not considered reasonable or necessary for ongoing management of stable PAD and is not covered unless revascularization is actively being planned.