Venous thromboembolism (VTE) investigation and management – NICE advice

This is an updated guideline from NICE on the investigation and management of venous thromboembolism (VTE). It was published in Mar 20.

There is also a very good visual summary, which outlines investigations and gives a superb summary on treatment options.

There are quite a few changes in this guideline and I have outlined these at the top, before doing a general summary.

So what is new in this guideline?

PERC - the Pulmonary Embolism Rule out Criteria.

If, as a clinician, you feel that PE is unlikely, but you're not quite sure, then consider doing a PERC test (see below). This can help you be more confident in ruling out a PE.

Anticoagulate patients when a D-dimer result will take more than 4 hrs to come back.

If you have been suspicious enough to do a Well's score for PE or DVT, but it suggests that VTE is unlikely, you will go on to do a d-dimer. If that d-dimer result can not be returned within 4 hrs, then anticoagulate the patient.

Point of care d-dimer tests.

Choose a fully quantitative one. Consider using an age adjusted threshold in those over 50.

Interim anticoagulation and blood tests.

Before starting any anticoagulation, do bloods (as below). Don't wait for the results before starting anticoagulation.

Choice of anticoagulation.

Since the last guidance came out, the DOACs have become more widely used. Apixaban or rivaroxaban should be used first line (they are cheaper than dabagatrin in this scenario).

Weight of the patient and anticoagulation.

Whilst on anticoagulation, consider regular monitoring of treatment for patients under 50kg or over 120kg. See below.


Previous advice was to use stockings in patients after DVT for 2 yrs. Now they advice that you can use them for symptom relief, but shouldn't use them routinely after DVT.

Investigations for possible cancer after VTE.

In the last guideline, there was quite a long list of advised investigations looking for cancer in patients with unprovoked VTE. It has now been shown that these aren't necessary. Patients should be assessed with bloods (see below) and history and then further investigations should only be done if indicated.

How should we assess a patient with a possible DVT?

Do a Well's score. If a patient has features of both DVT and PE, then base assessment and investigations on clinical judgement.

  • Well's score 2 or more - DVT likely.
  • Well's score 1 or less - DVT unlikely.

What investigations should we do for a 'likely' DVT?

Proximal leg USS. If this is negative, do a d-dimer. If the d-dimer is positive, repeat the USS at 6-8 days.

If you can't get an USS within 4 hrs, then do a d-dimer and anticoagulate the patient. Then do the USS within 24 hrs.

If the USS and d-dimer are negative, then stop any anticoagulation, look for alternative causes and safety-net.

What should we do if the Well's score suggests that DVT is unlikely?

It is worth noting that NICE doesn't really give the option of not investigating at all. However, many of us may do a Well's score hoping to further reassure ourselves and the patient that DVT is unlikely, so I would suspect that many of us would not go on to do a d-dimer if we didn't clinically think that DVT was likely and if the Well's score is low.

Nice advises to do a d-dimer if the Well's score gives an 'unlikely' outcome. If the result can not be got within 4 hrs, then start anticoagulation.

  • D-dimer positive - offer proximal leg USS within 4 hrs OR
  • D-dimer negative - no further investigations needed. Safety-net.

NB - if proximal leg USS is not available within 4 hrs, then anticoagulate and do an USS within 24 hrs.

What about point of care D-dimer testing?

NICE advises considering a point of care d-dimer test, if a lab result is not immediately available. If used, choose a fully quantative one and consider an age adjusted threshold for patients over 50.

How should we initially assess a patient for a possible PE?

Consider a PERC score. If your clinical suspicion of a PE is low then consider doing a 'PERC' score. I had never heard of this. Basically it is a few questions, similar to the Well's score. If it is negative, then only about 1.8% of patients would actually be found to have a PE later. The idea is to reassure clinicians that PE is unlikely and to reduce the need for d-dimer tests, anticoagulation and referral etc. What do they mean by a 'low clinical suspicion'? If your clinical judgment, based on your overall clinical impression and on what alternative diagnoses there are, suggests less than a 15% chance of PE, then that would be a 'low clinical suspicion'. If you want to read more about the PERC score, there is some good information here. 

What do we do if the PERC score is positive or if we don't do one?

Do a Well's score.

If the Well's score suggests a likely PE:

  • Refer for further assessment.
  • If further investigation is not immediately available, then anticoagulate the patient.

If the Well's score suggests that PE is unlikely:

Do a d-dimer. If the result is not available within 4 hrs, then anticoagulate the patient.

  • Positive d-dimer - manage as if the Well's score had suggested that a  PE was likely.
  • Negative d-dimer - consider other causes and safety-net.

How should we manage interim anticoagulation (ie whilst awaiting the results of investigations)?

Ideally choose anticoagulation that can be continued for treatment too.

Do FBC, UE, LFT, PT, APTT. Don't await the results of these tests to start anticoagulation. Act on any results within 24 hrs.

What anticoagulation should we choose?

Remember that the visual summary of the guideline has a really good section on anticoagulation.

1st line - apixaban or rivaroxaban (both cheaper than other DOACs).

2nd line - either of the following options:

  • LMWH for 5d followed by dabigatran or edoxaban OR
  • LMWH + VKA for 5d then VKA alone once INR is above 2.0 on 2 consecutive readings.

 Are there any special considerations when choosing what anticoagulant to use?


For patients at the extremes of weight (< 50kg, or > 120kg), consider regular monitoring of treatment. NICE advises to note the cautions in the SPCs and to follow local guidelines or seek specialist or MDT advice.

Renal impairment or established renal failure.

If using dabagatrin, creatinine clearance must be 30ml/min or more.

If creatinine clearance is 15ml/min or less, then use LMWH alone, or unfractionated heparin (UFH), or LMWH/UFH + VKA then VKA alone until INR is stabilised.


Consider a DOAC. Otherwise use LMWH + VKA then VKA alone.

Take into account the type of tumour, other medications and the bleeding risk.

If their cancer is in remission, then treat as per anyone else.

Triple positive antiphospholipid syndrome.

Use LMWH + VKA, then VKA alone.

What should you do if there is treatment failure?

  • Check compliance.
  • Address other possible sources of hypercoagulability.
  • Increase the dose, or use an anticoagulant with an alternative mechanism of action.

How long should we treat patients for?

Provoked VTE

3m, as long as the provoking factor is no longer present.


3 to 6m (most patients will be on it for 6m and some may continue beyond this).

Unprovoked VTE

3m. Consider continuing anticoagulation if the risk of recurrence is felt to be high and if there is no additional bleeding risk. Discuss the pros and cons with the patient. It is felt that generally the benefits of continuing treatment outweighs the risks.


If the HASBLED score is 4 or more, then consider stopping anticoagulation if the risks can not be modified.

If we continue anticoagulation, which anticoagulant should be used?

Generally, we can continue the same one. If the original option hasn't been well tolerated and if it is indicated (ie depending on renal function, no antiphospholipid syndrome etc), then switch to apixiban.

Patients should be reviewed at least annually for their risk of recurrence, their bleeding risk and for their treatment preference.

If the patient declines further anticoagulation, should we use anything?

Consider aspirin at 75 to 150mg daily.

When thinking about underlying cause, should we be doing any tests for cancer?

Studies suggest that there is no benefit to routinely screening patients for cancer. We should do the blood tests we are doing anyway (FBC, UE, LFT, PT, APTT) and offer a physical examination and assessment. Any further tests should only be done if suggested by clinical features, as per the NICE guidelines on suspected cancer.

Who should we be testing for a thrombophilia?

We should not be testing for thrombophila if:

  • VTE was provoked.
  • Anticoagulation is going to continue anyway.
  • the patient has not themself had a VTE, but is a 1st degree relative of someone who either has had a VTE or has a thrombophilia.

Consider testing for antiphospholipid syndrome if:

  • The DVT was unprovoked and you are planning to stop anticoagulation. Be aware that the results may be affected by being on anticoagulation. Specialist advice may be needed.

Consider screening for a thrombophilia if:

  • The DVT was unprovoked and it is planned to stop anticoagulation and the patient has a 1st degree relative with a VTE. Be aware that the results may be affected by being on anticoagulation. Specialist advice may be needed.

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