The Society for Vascular Technology of
Great Britain and Ireland
PHYSIOLOGICAL MEASUREMENT SERVICE SPECIFICATIONS
Vascular Technology
Arterial Duplex - lower limb, upper limb, assessment of bypass
graft/stent patency
This investigation uses ultrasound to image and assess flow in the major arteries of the
lower or upper limbs. An ultrasound probe is used to scan the legs or arms to assess the
location, extent and type of any occlusive or aneurysmal disease of the major arteries. For
the lower limbs, the arteries can be scanned from the aorta in the abdomen down to ankle
and where appropriate onto the foot. For the arms, the arteries can be scanned from the
neck down to the wrist and where appropriate into the hand. Arterial disease is less
common in the arms than in the legs. This test is also used for surveillance following
interventions such as a bypass graft or stent. It is used to identify the location, extent and
severity of arterial disease in order to facilitate clinical or surgical management decisions.
Patients, who experience pain in the legs on walking (claudication), in arms on movement
or have pain in the limbs at rest and/or ulceration may require this investigation. Note: For
leg assessments the measurement of ankle brachial pressure index (ABPI) is a good
indicator of whether disease is present or not and its severity. This is often carried out prior
to a duplex examination. Where ABPI have not been already been measured, they will
often be done at the same time as the duplex investigation.
1. PATIENT PATHWAY
An Arterial Duplex assessment is a major diagnostic test in the pathway of patients with
suspected lower or upper limb arterial disease, and particularly where any intervention
may be needed. It is used in surveillance programs to follow up patients who have had an
intervention such as a bypass graft or stent.
Guidance is given to implementation of duplex in the National Institute for Clinical
Excellence (NICE) publication’ lower limb peripheral arterial disease diagnosis and
management cg147’ 20121 and Vascular Society Great Britain and Ireland document The
Provision of Services for Patients with Vascular Disease 20122
2. REFERRAL
Clinical Indications
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These include:
 Investigation or follow-up of patients with claudication or ischaemic symptoms e.g.
rest pain and/or arterial ulceration
 Assessment of patients with known arterial disease
 Pre-procedure assessment for planning of intervention
 Follow-up to determine technical adequacy of intervention i.e. post angioplasty
and/or stent placement
 Follow-up of bypass grafts to detect intrinsic stenosis or progression of disease,
which may threaten graft patency
 Evaluation of aneurysm, pseudoaneurysm, arterial-venous fistula
 Evaluation of arterial trauma
Further guidance is given in the Society for Vascular Ultrasound (SVU) professional
performance guidelines for vascular technology ‘Upper extremity arterial duplex
evaluation’3 ‘Abdominal aorto-iliac arterial duplex evaluation’4 and ‘Lower extremity arterial
duplex evaluation’
5
Contra indications
Scans may be limited due to high body mass index (BMI) and in the presence of ulcers,
wounds, bandaging or casts.
3. EQUIPMENT
Specification
A high resolution imaging ultrasound duplex scanner which has colour, power and pulsed
Doppler modalities is required. A midrange (covering nominal frequencies of 4-7MHz)
linear array transducer (probe) should be available for scanning the leg below the groin
and for scanning the arm. A lower frequency transducer (covering nominal frequencies of
2.5–4MHz) should be available scanning the aorto-iliac segment (above the groin). A highfrequency linear array transducer (covering frequencies above 7MHz) may be useful for
scanning the forearm arteries.
There should be facilities to record images/measurements6. The Royal College of
Radiologists (RCR) has more detailed technical standards for ultrasound equipment7.
It should be noted that a range of relatively low cost portable scanners is now available,
not all of which will suitable for vascular work.
It is important that the duplex scanner is of ergonomic design as explained in the health
and safety section to minimise the risk of operator work related musculoskeletal
disorders8.
Maintenance
Equipment should be regularly safety-tested and regularly maintained in accordance with
the manufacturer’s recommendations. Further information is available from the British
Medical Ultrasound Society (BMUS): ‘Extending the provision of ultrasound services in the
UK’9.
Quality Assurance (QA) and Calibration
QA procedures should be in place to ensure a consistent and acceptable level of
performance of all modalities of the duplex scanner. Such procedures are likely to be set
up with involvement from Medical Physics Departments or service engineers as they
require specialist skills and will require both imaging and flow phantoms.
Detailed guidance on the QA of the imaging modality of duplex scanning is contained in
the Institute of Physics and Engineering in Medicine (IPEM) Quality Assurance of
Ultrasound Imaging Systems report 10210. The IPEM report 70 Testing of Doppler
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Ultrasound Equipment, contains extensive information relating to performance testing of
the pulsed and colour Doppler modalities of duplex scanners11.
Further general guidance is available in ‘Guidelines for Professional working standards:
Ultrasound practice’12.
Set up procedures
An appropriate probe should be selected. All duplex control settings should be set to
defaults appropriate for peripheral arterial investigation. Equipment manufacturers will
normally provide appropriate default peripheral arterial settings.
Infection control
There are no nationally agreed standards for vascular ultrasound scanning but local
infection control policies should be in place. BMUS13 advises that users should refer to
manufacturer’s instructions for the cleaning and disinfection of probes and transducers and
general care of equipment. It should be noted that ultrasound probes can be damaged by
some cleaning agents and so manufacturer’s specifications should always be followed.
Sterile ultrasound gel and sheaths should be available and used in appropriate cases.
Accessory equipment
Examination couches and scanning stools/chairs must be of an appropriate safety
standard and ergonomic design to prevent injury, particular consideration should be given
to reducing the risk of operator work related musculoskeletal disorders7.
4. PATIENT
Information and consent
There is no legal requirement that written patient consent be obtained prior to an
extracranial carotid arterial duplex examination. However, patients should be fully informed
about the nature and conduct of the examination so that they can give verbal consent. It is
desirable that this information is provided in written format and is given prior to their
attendance14. This information should also be verbally explained to the patient when they
attend for the investigation. Examples of additional patient information to include can be
found at the RCR http://www.rcr.ac.uk/docs/patients/worddocs/CRPLG_US.doc
The Circulation Foundation produces leaflets which provide further information to patients:
www.circulationfoundation.org.uk.
Clinical history
The written referral for the investigation should contain relevant clinical history. But this
information should be verified and clarified for any discrepancies
This should include any symptoms or history of lower or upper extremity arterial disease
and details of any previous interventions e.g. angioplasty, stent insertion or bypass graft.
The nature and duration of symptoms should be established; and relevant risk factors
established e.g. hypertension4 5 6.
Preparation
No specific preparation is required for scanning the leg arteries below the groin6 or for
scanning the arteries of the arm4. Access will be required to the patient’s legs or arms.
Scanning may be difficult in patients with leg ulcers or open wounds or high BMI. Sterile
dressings or cling film will allow imaging over these sites. Bowel gas often makes imaging
of the aorta and iliac segment5 (the arteries in the abdomen which supply the legs) difficult.
Some centres use advanced preparation, such as fasting for 6 hours prior to the scan, in
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order to improve imaging of these vessels. Particular care should be taken with any advice
given to diabetic patients prior to a scan appointment.
5. ENVIRONMENT
A private room (or curtained off area in a larger multiscan bay unit) is required to carry out
the scan which should be darkened, with no natural light entry, and preferably dimmer
switch lighting.
Air conditioning may be required due to heat production from the scanning equipment. The
ultrasound manufacturer should supply appropriate guidance on air conditioning
requirements.
Further general guidance on the environment is given in the BMUS documents:
Extending the provision of ultrasound services in the UK and Guidelines for Professional
Working Standards Ultrasound Practice8.
On occasion, assessment for lower or upper limb arterial disease may also need to be
carried out in other localities e.g. in theatre, theatre recovery or at the patient’s bedside.
These scans may be somewhat limited due to poor environmental conditions.
6. PROCEDURE
The request will specify whether one or both limbs should be scanned. The transducer is
positioned on the leg, arm or on the abdomen. The transducer is manipulated to obtain
optimal images of the arteries. The major arteries of the limbs, and where appropriate the
arteries in the abdomen supplying the legs, should be imaged to visualise any areas of
pathology. Flow in these arteries should be assessed using the colour and pulsed Doppler
modalities. Further guidance is given in the SVU professional performance guidelines for
vascular technology ‘Upper extremity arterial duplex evaluation’4 ‘Abdominal aortoiliac
arterial duplex evaluation’5 and ‘Lower extremity arterial duplex evaluation’6. The referral
will indicate any specifically required additional investigation, such as thoracic outlet
syndrome15 or popliteal entrapment16, where the limbs need to be evaluated in particular
positions.
Protocol
A local protocol should be set up in accordance with professional guidelines4 5 6. It is
important to follow the sequence of events outlined in the protocol to avoid missing
important information.
As a minimum, the leg examination should include assessment of the common femoral,
superficial femoral, popliteal and calf arteries. In addition, the aorta-iliac arteries may be
examined where the referrer or the local protocol specifies this or where findings or
symptoms indicate disease may be present in this segment. For bypass grafts, the entire
length of the graft should be scanned paying particular attention to the anastomoses. The
inflow and outflow should also be assessed. Similarly, for stent insertions, particular
attention should be given to imaging and assessing flow through the stent together with an
assessment of the inflow and outflow to the stented area.
Ankle brachial pressure indices may also be included in the protocol, particularly where
these measurements have not been carried out prior to this investigation.
As a minimum, the arm examination should include assessment of the subclavian, axillary,
brachial, radial and ulnar arteries.
For both leg and arm examinations, any areas where the colour flow Doppler appears
disturbed should always be interrogated with pulsed Doppler. The highest peak systolic
velocity should be measured at the site of the disturbance or narrowing (Vs) and in a
normal area of the artery just proximal to the narrowing (Vp). Care should be taken to
0
ensure that the Doppler angle is 60 or less when recording velocity measurements.
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Documentation
It is recognised that ultrasound scanning is operator dependent and recording of images
may not fully represent the entire examination. Recording of images should be done in
accordance with a locally agreed protocol. Images that document the findings of the
investigation are appropriate. Any stored images should have patient identification,
examination date, organisation and department identification.
Further explanation and guidance is given in section 4 of the UKAS Guidelines and SVT
image storage guidelines11 5.
The extent, location and morphology of any areas of plaque together with an indication of
the degree of any stenosis should be documented. The diameters of any areas where the
vessel appears dilated should be documented. A description of the shape of the Doppler
waveforms at different locations should be included.
7. INTERPRETATION & REPORT
Criteria
The main criterion used to grade the degree of narrowing in a lower limb artery is the ratio
of Vs to Vp, known as the peak systolic velocity (PSV) ratio. The PSV ratio is used to
grade the severity of the narrowing. A PSV ratio of greater than 2 is used to define a
stenosis (narrowing) that is causing a greater than 50% reduction in the diameter of the
1.
artery1718 Changes in the shape of Doppler waveforms are important criteria in
determining the presence of disease. Multiphasic waveforms are representative of normal
flow, whereas monophasic/damped waveforms usually represent diseased flow. Criteria
for arm arteries are less well established, but it is widely acknowledged that the same
increased PSV ratios used for legs can be applied. Providers should take into
consideration the criteria used by other local organisations when agreeing upon criteria to
be used. This will help reduce the repeat testing that often occurs when a patient is
referred to another organisation.
Minimum report content
There are no specific recommendations for the structure and content of reports for upper
and lower arterial scans, but many referrers find a pictorial report with written conclusions
helpful. However, any evidence of plaque formation within the vessel lumen, wall
calcification or dilatation should be documented in the report together with severity and
location. Comments on the shape of the Doppler waveform at different locations should be
included in the report. Where the investigation was a surveillance or follow up scan of an
intervention, the report should give details of the intervention and should specifically
comment on the patency and flow in the region of the intervention. The report should note
the timing of the next surveillance scan. The report should be signed by the operator
carrying out the test. Where a computer generated reporting system is used, the
verification and authorisation procedure should be followed.
The report should be made available to the referring clinician on the day of the test. Any
urgent findings, , should be brought to the attention of the referring clinician immediately.
8. WORKFORCE
It is well recognised that ultrasound diagnosis is highly operator-dependent, and it is
essential that the workforce has the appropriate competencies and underpinning
knowledge.
This is achieved by ensuring the workforce has followed recognised education and training
routes. This applies to both medically and non-medically qualified individuals.
Education and training requirements
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All staff carrying out and reporting investigations should have successfully completed one
of the following education and training routes:
(i)
Full SVT accreditation (Accredited Vascular Scientist)
http://www.svtgbi.org.uk/assets/Uploads/Education/EdComm-Accreditation-2012v1.pdf
(ii)
Post graduate qualification in ultrasound imaging from a Consortium for
Accreditation of Sonographic Education (CASE) accredited course with successful
completion of a vascular module which has included clinical competency in venous
duplex scanning. A list of CASE accredited courses can be found at www.caseuk.org
(iii)
Radiologists, medical and surgical staff should have successfully followed the RCR
recommendations for training in vascular scanning to level 2 competencies in
peripheral extremity veins (Ultrasound training recommendations for medical and
surgical specialties. BFCR(05)2 www.rcr.ac.uk/docs/radiology/pdf/ultrasound.pdf
(iv)
Completion of the NHS Scientist Training Programme specialising in Vascular
Science and statutory registration as a Clinical Scientist with the Healthcare
Professions Council (HCPC).
http://www.nshcs.org.uk/assessment/learning-guides-2/
Regulation
It is important that both employees and employers are aware that although
ultrasonography is not currently a regulated profession, there is a move towards statutory
regulation of all healthcare science groups in the future. Current statutory or voluntary
registration includes:
(i) Registered on the SVT Voluntary Register
(ii) UK Registered Physicians on the General Medical Council (GMC) Specialist Register
(iii) Registered Clinical Scientist with Health Care and Professions Council (HCPC)
(iv) Registered on the National Voluntary Register for Sonographers held by the Society &
College of Radiographers (SCoR)
Maintaining competence
It is important that scanning competence is maintained by all personnel performing this
investigation either by performing a minimum number of scans each year or through a
CPD scheme. Criteria for ensuring continuing competence are set by the professional
bodies.
Continuing Professional Development (CPD)
Staff must undertake continuing professional development, to keep abreast of current
techniques and developments, and to renew and extend their skills.
I.
SVT accredited staff must maintain their accreditation by meeting the CPD
requirements of the SVT:
http://www.svtgbi.org.uk/assets/Uploads/Education/EdComm-Accreditation2012-v1.pdf
II.
Staff with a post graduate qualification in ultrasound imaging should meet the
CPD requirements of SCoR registration:
http://www.sor.org/learning/document-library/continuing-professionaldevelopment-professional-and-regulatory-requirements
III.
Medical and surgical staff should follow the requirements outlined for
maintenance of skills as well as the need to include ultrasound in their ongoing
CME:
www.rcr.ac.uk/docs/radiology/pdf/ultrasound.pdf
IV.
For Clinical Scientists maintain registration with CPD through the HCPC
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9. AUDIT, SAFETY & QA
Safety
The provider should be aware of the guidelines for the safe use of ultrasound equipment
produced by the Safety Group of BMUS. In particular, they should be aware of ultrasound
safety precautions related to vascular scanning. All staff should be aware of local safety
rules and resuscitation procedures.
Sonographers are at risk of work related musculoskeletal disorders. To minimise this risk
the scanner and its control panel, the examination couch and scanning stool must be of
appropriate safety standard and ergonomic design.
The published document by the Society of Radiographers (SCoR) ‘Prevention of Work
Related Musculoskeletal Disorders in Sonography’7 gives clear guidance on this issue as
well as ’Guidelines for Professional Working Standards Ultrasound Practice’11
QA and Audit
There are no specific requirements, but a mechanism of audit/quality control to ensure
patients continue to receive high level of diagnostic accuracy should be in place.
QA and audit programs should cover:
The BMUS document8 and UKAS Guidelines11 also give guidance. Equipment QA is
covered in section 3 of this document.
Websites:
www.rcr.ac.uk
www.bmus.org
www.svtgbi.org.uk
www.svunet.org
www.case-uk.org
www.ipem.ac.uk
www.hpc-uk.org
www.rcplondon.ac.uk
www.vascularsociety.org.uk
www.circulationfoundation.org.uk
www.sor.org
www.nice.org.uk
References:
1
NICE
guideline
Lower
Limb
Arterial
Disease
Diagnosis
and
Management:
http://publications.nice.org.uk/lower-limb-peripheral-arterial-disease-diagnosis-and-management-cg147
2 Vascular Society Great Britain and Ireland The Provision of Services for Patients with Vascular Disease
2012 http://www.vascularsociety.org.uk/library/vascular-society-publications.html
3 Society for Vascular Ultrasound Professional Performance Guidelines; Upper extremity arterial duplex
evaluation www.svunet.org/files/positions/UE-Arterial-Duplex-2011.pdf
4 Society for Vascular Ultrasound Professional Performance Guidelines; Abdominal aortoiliac arterial duplex
evaluation. www.svunet.org/files/positions/Abdominal-AortoIliac-Duplex-2011.pdf
5Society for Vascular Ultrasound Professional Guidelines; Lower extremity arterial duplex evaluation.
www.svunet.org/files/positions/0809-LowerExtremArterialD.pdf
6SVT
Guidance on Image Storage and use, for the vascular ultrasound scans 2012
www.svtgbi.org.uk/assets/Uploads/Resources/Final-SVT-Image-Storage-Guidelines-April-2012-PDF.pdf
7Standards
for
Ultrasound
Equipment’
Royal
College
of
Radiologists
2005
www.rcr.ac.uk/docs/radiology/pdf/StandardsforUltrasoundEquipmentJan2005.pdf pages 15-17
Page 7 of 8
‘Prevention of Work Related Musculoskeletal Disorders in Sonography - Society of Radiographers 2007
Extending the provision of ultrasound services in the UK’ BMUS 2003 http://www.bmus.org/policiesguides/pg-protocol01.asp
10 Quality Assurance of Ultrasound Imaging Systems’ IPEM report 102 2010
11 Testing of Doppler Ultrasound Equipment’ IPEM report 70 1994
12 Guidelines for Professional Working Standards Ultrasound Practice. www.bmus.org/policies-guides/SoRProfessional-Working-Standards-guidelines.pdf
13 www.bmus.org/policies-guides/pg-clinprotocols.asp
14
Improving
Quality
in
Physiological
Sciences
(IQIPS)
Standards
and
Criteria
http://www.iqips.org.uk/documents/new/IQIPS%20Standards%20and%20Criteria.pdf
15 Vascular Ultrasound How, Why and When Thrush Hartshorne Third Edition 2010 Chapter 10 Duplex
Assessment of upper-limb arterial disease
16 Vascular Ultrasound How, Why and When Thrush Hartshorne Third Edition 2010 Chapter 9 Duplex
Assessment of lower-limb arterial disease
17 Cossman D, Ellison J E, Wagner W H et al 1989 Comparison of contrast arteriography to arterial mapping
with colour-flow duplex imaging in the lower extremities. Journal of Vascular Surgery 10: 522-529
18 Sensier Y., Hartshorne T, Thrush A et al 1996 A prospective comparison of lower limb colour-coded
duplex scanning with arteriography.’ European Journal of Vascular and Endovascular Surgery 11:170-175’
8
9
th
Final Version 6 August 2010
Version I.I SVT Professional Standards Committee November 2012
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