Quality standard

Quality statement 3: Proximal leg vein ultrasound scan for a 'likely' deep vein thrombosis Wells score

Quality statement

People aged 18 and over with a deep vein thrombosis (DVT) Wells score of 2 points or more have a proximal leg vein ultrasound scan within 4 hours of it being requested. [2013, updated 2021]

Rationale

People aged 18 and over with a suspected DVT need to have a proximal leg vein ultrasound scan quickly to diagnose or rule out a DVT so that treatment can be started promptly if needed. The scan should be done within 4 hours of the request to avoid unnecessary interim anticoagulation treatment and, if DVT is ruled out, alternative diagnoses can be investigated promptly.

Quality measures

The following measures can be used to assess the quality of care or service provision specified in the statement. They are examples of how the statement can be measured and can be adapted and used flexibly.

Structure

Evidence of the availability of staff to perform proximal leg vein ultrasound scans for people aged 18 and over with a DVT Wells score of 2 points or more within 4 hours of it being requested.

Data source: No routinely collected national data for this measure has been identified. Data can be collected from information recorded locally by healthcare professionals and provider organisations, for example from staff rotas.

Process

Proportion of people aged 18 and over with a DVT Wells score of 2 points or more who have a proximal leg vein ultrasound scan within 4 hours of it being requested.

Numerator – the number in the denominator who have a proximal leg vein ultrasound scan within 4 hours of it being requested.

Denominator – the number of people aged 18 and over with a DVT Wells score of 2 points or more.

Data source: No routinely collected national data for this measure has been identified. Data can be collected from information recorded locally by healthcare professionals and provider organisations, for example from patient records.

Outcome

Prescribing rates of interim therapeutic anticoagulation to prevent DVT.

Data source: No routinely collected national data for this measure has been identified. Data can be collected from information recorded locally by healthcare professionals and provider organisations, for example from prescribing systems.

What the quality statement means for different audiences

Service providers (such as secondary care services) ensure that ultrasound scanning equipment and staff are available to perform proximal leg vein ultrasound scans for people aged 18 and over with a DVT Wells score of 2 points or more within 4 hours of the scan being requested. They ensure that written clinical protocols are in place so that, if it is not possible to have the scan result within 4 hours, people are offered a D‑dimer test, then interim therapeutic anticoagulation until the scan results are obtained (within 24 hours) and treatment is reviewed.

Healthcare professionals (such as GPs, specialists and nurses) are aware of referral pathways for proximal leg vein ultrasound scans, and refer people aged 18 and over with a DVT Wells score of 2 points or more to have this imaging. If it is not possible to obtain the scan result within 4 hours, they offer a D‑dimer test, then interim therapeutic anticoagulation and an ultrasound scan within 24 hours.

Commissioners (such as clinical commissioning groups) ensure that services have referral pathways and written clinical protocols in place so that people aged 18 and over with a DVT Wells score of 2 points or more can have a proximal leg vein ultrasound scan within 4 hours of it being requested, or within 24 hours if this is not possible. They also ensure that services have the equipment and capacity to perform this imaging within this timeframe.

People aged 18 and over who have signs and symptoms of a deep vein thrombosis (blood clot) and are referred for an ultrasound scan have the scan within 4 hours of the referral being made. If this is not possible, they are given the scan within 24 hours, and offered a blood test to measure a protein called D‑dimer, which can indicate whether there is a blood clot, and an anticoagulant (medicine to treat blood clots) to take while waiting for the scan.

Definition of terms used in this quality statement

DVT Wells score of 2 points or more

A 'likely' DVT Wells score, which is a score that predicts the probability of DVT for people with suspected DVT, estimated using the Wells clinical prediction rule:

Two-level DVT Wells score

Clinical feature

Points

Active cancer (treatment ongoing, within 6 months, or palliative)

1

Paralysis, paresis or recent plaster immobilisation of the lower extremities

1

Recently bedridden for 3 days or more, or major surgery within 12 weeks requiring general or regional anaesthesia

1

Localised tenderness along the distribution of the deep venous system

1

Entire leg swollen

1

Calf swelling at least 3 cm larger than asymptomatic side

1

Pitting oedema confined to the symptomatic leg

1

Collateral superficial veins (non-varicose)

1

Previously documented DVT

1

An alternative diagnosis is at least as likely as DVT

-2

Clinical probability simplified score

Points

DVT likely

2 points or more

DVT unlikely

1 point or less

[NICE's guideline on venous thromboembolic diseases, recommendation 1.1.2]

Equality and diversity considerations

NICE's guideline on venous thromboembolic diseases covers people aged 18 and over because the evidence for the recommendations focused on this age group. This statement applies to people aged 18 and over, but clinical judgement should be used when treating people aged between 16 and 18 for suspected DVT.

Heparins are a type of anticoagulant used to prevent VTE. They are of animal origin and this may be of concern to some people because of religious or ethical beliefs. The suitability, advantages and disadvantages of alternatives to heparin should be discussed with the person.