Who sets the standard in the United States
The US model is more codified than the Italian one because report structure is tied to vascular laboratory accreditation, which in turn affects reimbursement. Report elements are therefore not merely good practice: they are verified at accreditation survey.
| Body | Role regarding the report | Reference documents |
|---|---|---|
| AIUM Ultrasound, all applications |
Publishes the practice parameters that define minimum performance and documentation requirements for every ultrasound examination, including the mandatory content of the report. | Practice Parameter for Documentation of an Ultrasound Examination; territory-specific parameters for extracranial cerebrovascular duplex (2022), peripheral arterial ultrasound (2021) and peripheral venous ultrasound (AIUM/ACR/SPR/SRU, 2024). |
| SVU Vascular ultrasound |
The only US professional society devoted entirely to vascular ultrasound. Its Professional Performance Guidelines define, examination by examination, the segments to be studied, the measurements to be acquired and the content of the report. | SVU Professional Performance Guidelines, 2019 edition (twenty freely downloadable protocols) and Quality Assurance Guidelines, 2018. |
| IAC Accreditation |
The Intersocietal Accreditation Commission sets the standards for the vascular laboratory: staff qualifications, written protocols, report content, turnaround times, quality improvement programme and results correlation. | IAC Standards and Guidelines for Vascular Testing Accreditation. |
| SRU Radiology ultrasound |
Multidisciplinary consensus conferences; the most widely cited remains the one on velocity criteria for carotid stenosis, still a worldwide reference. | Grant EG et al., Radiology 2003 (SRU Consensus Conference). |
| SVS, AVF, AVLS, ACC/AHA Clinical |
Define when duplex is the first-line test and which thresholds generate a management decision — the guidance the report must enable the clinician to apply. | SVS/AVF/AVLS varicose veins (2022 and 2023); ACC/AHA lower extremity peripheral artery disease (2024); CHEST and ASH for venous thromboembolic disease. |
| ARDMS, CCI, ARRT Credentials |
Certify individual competence: RVT (ARDMS), RVS (CCI), Vascular Sonography (ARRT). IAC accreditation requires credentialed staff. | Certification pathways of the respective bodies. |
The two-signature model: technologist and interpreting physician
The deepest organisational difference from the Italian model is that performing the study and reporting it are two distinct acts carried out by two distinct professionals. This separation explains almost every formal peculiarity of the US report.
| Stage | Who | Output |
|---|---|---|
| Acquisition | Credentialed vascular technologist / sonographer (RVT, RVS, VS) | Images and measurements following the laboratory's written protocol, archived to PACS. |
| Technical summary | The same technologist | Preliminary worksheet (or technical impression): a structured sheet holding all measurements plus a preliminary technical observation. It is not a report and has no standalone diagnostic authority. |
| Interpretation | Interpreting physician qualified to IAC standards | Final report: the signed document and the only official diagnostic act. |
What this means for the document
Because the interpreter did not perform the study, the report must carry every piece of
information needed for interpretation without relying on the operator's recall. Hence the
exhaustive list of minimum elements, the tabular format for measurements and the requirement
to document every protocol segment with an image. It is also why the US model is the easiest
to translate into reporting software.
Note for readers outside the US
In Italy there is no legal equivalent of the vascular technologist with autonomy to acquire
and issue a preliminary report. The two-signature model is not transferable as such — but its
documentation requirements are, because they are independent of the professional arrangement.
Minimum report elements under AIUM
The Practice Parameter for Documentation of an Ultrasound Examination lists the elements every ultrasound report must contain. They apply across all territories and form the backbone onto which the territory-specific protocols graft their clinical content.
| # | Element | Status | Content |
|---|---|---|---|
| 1 | Patient identification | Required | Name, unique identifier, date of birth — on every page of the report and on every image. |
| 2 | Facility identification | Required | Name and location of the laboratory; accreditation number where applicable. |
| 3 | Date of examination | Required | Date performed; where different, also the date the report was issued. |
| 4 | Examination performed | Required | Precise designation matching the billing code (CPT): complete or limited, unilateral or bilateral. |
| 5 | Indication / reason for examination | Required | Reason for referral, symptoms, suspected diagnosis. This field underpins both appropriateness and reimbursement. |
| 6 | Comparison studies | Required if available | Type and date of prior studies used for comparison. |
| 7 | Technique / description of examination | Required | Modalities used (B-mode, colour, spectral Doppler), segments examined, patient position, manoeuvres. |
| 8 | Findings | Required | Description and measurements, typically tabulated by segment and by side. |
| 9 | Limitations | Required if present | Segments not visualised and why (body habitus, bowel gas, dressings, shadowing calcification, poor cooperation). |
| 10 | Impression / conclusion | Required | Concise diagnostic judgement answering the stated indication; comparison with the prior study; recommendation where appropriate. |
| 11 | Signature of the interpreting physician | Required | Signature (electronic acceptable) of the interpreting physician only; the technologist does not sign the final report. |
| 12 | Retention of images and report | Required | Images and report retained per state law and institutional policy. |
The practical test
An AIUM-compliant report must allow a second physician who never saw the patient to reconstruct
what was done, what was measured, what could not be seen and why the conclusion reads as it
does. Apply this test to any report template.
IAC accreditation requirements
The IAC vascular testing standards reach beyond the individual report to the whole system that produces it. They are the reason the US model is so formalised.
- Written protocols. For every examination offered, a written protocol defining segments studied, mandatory measurements, images to be acquired and diagnostic criteria used.
- Stated and validated diagnostic criteria. The velocity thresholds in use must be explicit and verified against a reference standard (angiography, CTA, surgical findings). Applying published criteria without internal validation is not acceptable.
- Staff qualifications. Credentialed technologists and interpreting physicians with documented training and experience, plus continuing medical education.
- Minimum report content — essentially the AIUM elements, with explicit emphasis on comparison with prior studies and on the interpreting physician's signature.
- Turnaround time. The laboratory must define, meet and document a maximum interval between examination and availability of the signed report.
- Quality improvement programme. Documented periodic meetings, case review, results correlation and tracked corrective actions.
- Critical findings management. A written procedure for immediate communication of findings requiring urgent action, with the communication recorded.
The transferable point
The laboratory must state the criteria it uses. The minimum equivalent in any report is
to name the method (NASCET) and the source of the criteria (SRU 2003, ESVS, SIDV) alongside the
degree of stenosis. It is what makes a number interpretable and comparable between centres.
Structure of the SVU protocols
The SVU Professional Performance Guidelines all share the same layout, which is in practice the template for building a laboratory protocol. It is worth knowing because it maps directly onto a reporting form in software.
| Protocol section | Content |
|---|---|
| Purpose / scope | What the examination is intended to demonstrate and which questions it can answer. |
| Indications | Recognised indications — the field that links the report to appropriateness. |
| Contraindications / limitations | Situations where the study cannot be performed or has reduced value. |
| Patient preparation | Fasting, positioning, withheld medication, removal of dressings. |
| Equipment | Transducer type and frequency, presets, spectral and colour Doppler requirements. |
| Procedure / technique | Scanning sequence segment by segment, manoeuvres, insonation angle. |
| Required documentation | An exhaustive list of mandatory images and measurements. This is the section with no counterpart in the Italian tradition. |
| Diagnostic criteria | Thresholds used and their source. |
| Physician interpretation / report | What must appear in the final report for that protocol. |
| Quality assurance | How the accuracy of that examination's results is verified. |
Image documentation: the rule that carries the most weight
The US model prescribes which images must be archived, not only which findings must be described. The governing principle is that what is not documented was not examined.
- Every segment in the protocol must have at least one archived image, even when the finding is normal.
- Every spectral image must display the angle correction and the sample volume position, and be annotated with vessel, side and level.
- Every abnormal finding must be documented in at least two modalities (B-mode and colour, or colour and spectral) and, where relevant, in two planes.
- Annotation must remain consistent between serial studies on the same patient, so that follow-up is genuinely comparable.
- Images form part of the medical record and are subject to the same retention obligations as the report.
Translating this into a reporting form
Attach an image field and a measurement field to each protocol segment, and prevent the report
from being finalised until mandatory segments are either completed or explicitly flagged
"not assessable" with a reason. This reproduces in software what the US model achieves through
the technologist's worksheet.
Required content by vascular territory
A synthesis of the SVU protocols and AIUM practice parameters for the territories covered by vascular reporting. Numeric thresholds are collected on the guidelines page.
7.1 · Extracranial cerebrovascular duplex
| Requirement | Content |
|---|---|
| Mandatory segments | Proximal, mid and distal CCA; bulb; proximal, mid and distal ICA; ECA; vertebral artery (V1–V2); subclavian artery — bilaterally. |
| Mandatory measurements | PSV and EDV for each of the above, bilaterally; ICA/CCA ratio. |
| B-mode | Plaque description: location, extent, echogenicity, surface, shadowing calcification. |
| Vertebral arteries | Flow direction must be explicitly stated: antegrade, retrograde or to-and-fro. |
| Reporting criteria | Stenosis reported in categories, with explicit statement of the criteria applied (typically SRU 2003, NASCET method) and the threshold values the laboratory uses. |
| Stents | Dedicated velocity criteria, distinct from those for the native artery; PSV at the stent inflow, body and outflow. |
7.2 · Lower extremity arterial duplex and segmental pressures
| Requirement | Content |
|---|---|
| Mandatory segments | Distal aorta and iliacs where accessible, common femoral, bifurcation, profunda femoris, proximal/mid/distal superficial femoral, popliteal, tibioperoneal trunk, anterior tibial, posterior tibial, peroneal. |
| Mandatory measurements | PSV and waveform in every segment; at stenoses, PSV at the point of maximum velocity and in the normal proximal segment, with the peak systolic velocity ratio calculated and stated. |
| Associated pressure study | Segmental pressures, ABI and — in diabetic or renal patients — TBI. Pulse volume recordings and exercise testing where the protocol provides for them. |
| Occlusions | Extent, level of reconstitution, collateral pathways. |
| Bypass and stent surveillance | PSV throughout the conduit, proximal and distal anastomoses, ratio at stenoses; graft flow volume where the protocol requires it. |
| Aneurysms | Popliteal and femoral: diameter, mural thrombus, patent lumen. |
7.3 · Upper extremity arterial duplex, segmental pressures and TOS
| Requirement | Content |
|---|---|
| Mandatory segments | Subclavian, axillary, brachial, radial, ulnar; palmar arch where digital symptoms are the question. |
| Measurements | PSV and waveform per segment with side-to-side comparison; upper extremity segmental pressures. |
| Positional manoeuvres | Dedicated thoracic outlet syndrome protocol: signal recorded in the neutral position and in provocative positions. |
| Cold immersion test | Where digital vasospasm is suspected. |
| Radial artery as conduit | Dedicated pre-CABG protocol: diameter, calcification, instrumented Allen test. |
7.4 · Lower extremity venous duplex — suspected DVT
| Requirement | Content |
|---|---|
| Extent of the study | Complete protocol from the common femoral vein to the tibial and peroneal veins, with muscular veins included per laboratory policy. The report must state whether the study was complete or limited (e.g. two-point compression). |
| Compression | Documented in transverse plane, paired images without and with compression, at every protocol level. |
| Doppler | Spontaneity, respiratory phasicity, response to distal augmentation, side-to-side symmetry at the common femoral vein (a clue to iliac obstruction). |
| Thrombus description | Location, extent, occlusive or non-occlusive, acute or chronic appearance, free-floating component. |
| Superficial vein thrombosis | Vein involved, extent, distance from the junction. |
| Extravascular findings | Baker's cyst, haematoma, abscess, lymphadenopathy — reported as alternative diagnoses. |
7.5 · Lower extremity venous insufficiency (reflux)
| Requirement | Content |
|---|---|
| Position | Patient standing or in steep reverse Trendelenburg; the position must be stated in the report. |
| Manoeuvre | Distal compression–release (manual or cuff) or Valsalva at the junctions; specified in the report. |
| Mandatory measurements | Reflux duration in seconds at every site examined; saphenous diameters at standard levels. |
| Sites | Saphenofemoral and saphenopopliteal junctions; great and small saphenous veins at multiple levels; accessory veins; incompetent perforators with location and diameter; deep system. |
| Report | Reflux map and CEAP classification; standardised anatomical nomenclature. |
7.6 · Abdominal aorta, aortoiliac, mesenteric and renal
| Requirement | Content |
|---|---|
| Aorta — AAA screening | Maximum anteroposterior diameter measured outer wall to outer wall, perpendicular to the vessel axis; standard levels (suprarenal, juxtarenal, infrarenal, bifurcation); common iliac arteries. |
| Aortoiliac | Segmental PSV, stenosis location, ratio; downstream waveform morphology. |
| Mesenteric | Coeliac axis, superior and inferior mesenteric arteries: PSV, EDV, waveform; fasting study; for the coeliac axis, recordings in inspiration and expiration (median arcuate ligament). |
| Renal | PSV at the origin, mid and distal segment of each renal artery; aortic PSV for the renal–aortic ratio; intraparenchymal indices (RI, acceleration time) at upper, mid and lower pole; renal length. |
| Post-EVAR | Sac diameter, limb patency, systematic search for endoleak with colour and spectral Doppler; comparison with the previous diameter. |
| Preparation | Fasting must be stated; if not observed, it must be recorded as a limitation. |
7.7 · Haemodialysis access and vein mapping
| Requirement | Content |
|---|---|
| Preoperative vein mapping | Cephalic and basilic vein diameters at multiple levels, with and without tourniquet; depth from skin; patency and compressibility; radial and brachial artery diameter; Allen test; central vein assessment. |
| Access surveillance | Flow volume measured in the brachial artery (measurement site stated), outflow vein diameter and depth, usable cannulation segment. |
| Stenosis | Location (juxta-anastomotic, body, outflow, central veins), PSV within and proximal to the stenosis, ratio. |
| Complications | Thrombosis, pseudoaneurysm, aneurysm, haematoma, seroma, steal syndrome (with digital assessment where indicated), venous hypertension. |
| Report | Mandatory comparison with the previous flow volume: the trend, more than the absolute value, signals the problem. |
Writing the impression
The US impression is leaner than the Italian conclusion: a few numbered lines carrying the degree of stenosis or the diagnosis, the comparison with the prior study and, where relevant, a recommendation. The established conventions:
- Answer the stated indication. If the indication was "rule out DVT", the first line must say whether DVT is present or absent.
- One numbered point per question — it supports rapid reading and coding.
- State the criteria used to assign the degree of stenosis.
- Always include the comparison with the prior study and its date, with an explicit judgement: stable, progressed, improved.
- Report the limitations that qualify the conclusion, without using them as a blanket disclaimer.
- Recommendation on follow-up interval or further imaging, anchored to a cited guideline.
- Introduce no finding that does not appear in the findings section.
Example · carotid impression
1. 50–69% stenosis of the right internal carotid artery by SRU 2003 velocity criteria (NASCET method): PSV 186 cm/s, EDV 52 cm/s, ICA/CCA ratio 2.4. Heterogeneous bulb plaque with a smooth surface.
2. Left internal carotid artery: intima–media thickening without haemodynamically significant stenosis (PSV 78 cm/s).
3. Vertebral arteries patent with antegrade flow bilaterally.
4. Compared with the study of 12 March 2025 (right ICA PSV 174 cm/s): stable.
5. Recommend duplex follow-up in 12 months; earlier reassessment if ipsilateral neurological symptoms develop.
Why the numbered format helps
It makes the report directly comparable over time and reduces the risk of a secondary but
relevant finding disappearing inside a long paragraph. It is the element of the US model most
readily adopted elsewhere without disrupting local practice.
Quality assurance and results correlation
This is the part of the US model with no formal counterpart in Italy, and the part that gives the velocity criteria their credibility. The SVU Quality Assurance Guidelines and the IAC standards require the laboratory to verify its own accuracy on an ongoing basis.
- Systematic correlation of duplex results against the available reference standard: angiography, CTA, MRA, surgical findings, clinical outcome.
- Calculation of accuracy measures: sensitivity, specificity, positive and negative predictive value for the principal diagnostic categories.
- Documented periodic review of discordant cases, analysing the cause (technique, criteria, interpretation).
- Adjustment of criteria where correlation reveals systematic deviation — which is why different laboratories may legitimately use slightly different thresholds, each validated locally.
- Inter-operator verification and periodic image quality assessment.
- Equipment checks: periodic transducer testing and calibration.
Why this matters outside the US too
Published thresholds were validated on specific populations and equipment. Applying them without
internal verification is an act of faith. Even an informal but systematic correlation — comparing
your own carotid duplex studies against the CTAs performed — transforms awareness of your own
margins of error.
Critical findings and turnaround
- The laboratory must hold a written list of critical findings: proximal DVT, free-floating thrombus, acute arterial occlusion, symptomatic or rapidly enlarging aneurysm, endoleak with sac expansion, dissection, thrombosed dialysis access.
- Communication to the clinician must be direct and prompt, not left to report delivery.
- The communication must be recorded: recipient, time, method. The note forms part of the report.
- The laboratory must define a maximum interval between examination and availability of the signed report, and monitor compliance.
- The technologist's preliminary worksheet must not be released to the patient or used as a standalone basis for management.
Differences from the Italian model
| Aspect | US model | Italian model |
|---|---|---|
| Who performs and who signs | Technologist performs; physician interprets and signs. | The same physician performs, interprets and signs. |
| Format | Structured and tabular; minimum elements enumerated. | Narrative and descriptive, segment by segment. |
| Images | Exhaustive list of mandatory images per protocol. | Image documentation recommended, with no prescribed minimum. |
| Diagnostic criteria | Stated in the report and validated internally by the laboratory. | Reference to international consensus, rarely stated in the report. |
| Quality | Laboratory accreditation (IAC) with consequences for reimbursement. | Operator training and certification; no binding laboratory accreditation. |
| Results correlation | Mandatory and documented. | Not formally required. |
| Strength of the model | Verifiability, reproducibility, comparability between centres. | Continuity between performing the study, clinical judgement and responsibility. |
Practical synthesis
The strongest report achievable in Italian practice keeps the Italian architecture — indication,
technique, description, conclusion, signature — and grafts on four elements of the US model:
an exhaustive list of mandatory segments with explicit "not assessable" flagging, image
documentation per segment, a stated diagnostic criterion, and a numbered impression carrying the
comparison and the recommendation.
See report structure under Italian guidelines.
Sources
- AIUM. Practice Parameter for Documentation of an Ultrasound Examination. American Institute of Ultrasound in Medicine (aium.org).
- AIUM. Practice Parameter for the Performance of an Ultrasound Examination of the Extracranial Cerebrovascular System, 2022 (J Ultrasound Med).
- AIUM. Practice Parameter for the Performance of Peripheral Arterial Ultrasound Examinations Using Color and Spectral Doppler Imaging, 2021.
- AIUM/ACR/SPR/SRU. Practice Parameter for the Performance of a Peripheral Venous Ultrasound Examination, 2024 (aium.org).
- SVU. Professional Performance Guidelines, 2019 edition — twenty protocols (extracranial and intracranial cerebrovascular, upper and lower extremity arterial and venous duplex, segmental pressure studies, vein mapping, haemodialysis access, aortoiliac, mesenteric, renal, AAA screening, pelvic venous) (svu.org).
- SVU. Quality Assurance Guidelines for the Vascular Laboratory, 2018.
- IAC. Standards and Guidelines for Vascular Testing Accreditation. Intersocietal Accreditation Commission (intersocietal.org).
- SRU. Grant EG et al. Carotid artery stenosis: gray-scale and Doppler US diagnosis — Society of Radiologists in Ultrasound Consensus Conference. Radiology 2003.
- SVS / AVF / AVLS. Clinical Practice Guidelines for the Management of Varicose Veins of the Lower Extremities, part I (2022) and part II (2023) (jvsvenous.org).
- ACC/AHA. 2024 Guideline for the Management of Lower Extremity Peripheral Artery Disease (ahajournals.org).
- ARDMS. Registered Vascular Technologist (RVT) credential requirements (ardms.org); CCI Registered Vascular Specialist (RVS); ARRT Vascular Sonography.
This page is an operational summary for healthcare professionals and does not replace the original documents, which remain the only binding reference. AIUM practice parameters and IAC standards are periodically revised: always check the edition in force. Numeric diagnostic thresholds are collected on the guidelines page.