DVT and SVT Pathway

Referral

***UPDATE May 2024 - Please note that the pathway has been updated in line with NICE guidelines (1) and D-Dimer is now recommended for all patients with suspected DVT prior to anticoagulation (unless there are exceptions - listed in D-dimer section below).***

Referral information for patients with suspected DVT

Patients who meet the inclusion criteria should be referred to Community DVT service run by GP Care using the EMIS DVT template.

Click on the BNSSG DVT Pathway for details.

For patients who are excluded from the GP care DVT service then please refer to secondary care using local pathways.

Referral information for patients with thrombophlebitis or suspected superficial vein thrombus (SVT)

For patients with thrombophlebitis or suspected superficial vein thrombosis (SVT):

• See the Treatment pathway for a flow chart on appropriate management of SVT and when to refer.
• Patients requiring an ultrasound scan of their leg for suspected SVT can be referred to GP Care. (Exclusion criteria are the same as for DVT)
• For SVT that is less than 3cm from the junction with a deep vein, treatment dose anticoagulation is required for 3 months
• For SVT that is more than 5cm long, but not within 3cm of deep vein junction, prophylactic dose anticoagulation is required for 6 weeks.
• Anticoagulation will not be initiated for SVT which doesn’t meet the criteria above. This can be treated by the patient’s own GP with NSAIDs &/or topical agent.
• NICE guidance is also available https://cks.nice.org.uk/superficial-vein-thrombosis-superficial-thrombophlebitis#!scenario

Making a Referral to GP Care

Referral to GP Care will be through managed referrals on EMIS which will contain the referral document. Please see the Guide for making a managed referral for instructions on how to do this through your EMIS system.

The referral information must include an up to date patient phone number to enable the patient to be contacted by GP Care to arrange the scan appointment.

Please print out referral and attached patient information leaflet and give to the patient. The leaflet explains how the patient will be cared for on the GP Care Community DVT pathway, what happens if they are diagnosed with a DVT and who to call if GP Care are unable to contact them.

Next steps:

• GP care will contact the patient by phone within 2 hours of receiving the urgent referral within working hours or by 10am the next working day to confirm the scan appointment time.
• If GP Care is unable to contact the patient (having tried 2 / 3 times over a 2 hour period) they will inform the GP practice by phone.
• The patient should contact GP Care if they have not heard from them within 4 hours of referral within working hours or by 11am the next working day (patient telephone number on referral form).
• If a patient phones GP Care and GP Care has no record of the GP ultrasound request they will ask the patient to contact their own GP to re-refer.
• If patients do not attend their scanning appointment, GP Care will phone the patient to try and rebook them and if they are unable to contact the patient they will phone the GP practice the same day to inform them that the patient has not attended.
• Following the scan, the ultra-sonographer will inform the patient of the scan result and provide a scan report. Outcome information will be returned electronically to the GP.

Contact for GP in case of queries: victoria.lewis@gpcare.org.uk

If a patient does not meet the criteria for the GP Care DVT service then please consider referral to local Secondary Care DVT  Services.

Red Flags

Patients with the following red flags should be referred immediately to secondary care:

• Suspected diagnosis of pulmonary embolism
• Patients under 18 years of age (15 years and under to paediatrics. 16/17 years olds to adult services)
• Patients with a suspected upper limb (i.e.arm) DVT
• Other disease process or acutely ill patient that requires admission to secondary care
• Weigh over 165kg

GP Care can now (May 2024) accept patients who need hoist to transfer. They don't have a hoist in all clinics so referrers need to be aware that may have to wait for scan - or be referred to secondary care.

Initial management in primary care

Clinical judgement plays a key part in patient assessment and any patient can be referred direct for ultrasound scan when deemed clinically appropriate.

See Referral Section above for pathway diagram and complete the following steps:

• Complete the EMIS DVT template to record patient contact - this template includes the two level DVT Wells score.  
• Undertake an assessment of the patient’s general medical history and a physical examination to exclude other causes.
• If DVT is suspected, use of the two‑level DVT Wells score to estimate the clinical probability of DVT.

DVT Wells score 2 or more 

• Perform d dimer test and other bloods, (see d dimer section below), (NB. a negative d dimer in this group of patients does not mean that a scan is not required. If the scan is inconclusive then the negative d dimer will mean that a second scan is not required)

• Refer to GP Care for ultrasound

DVT Wells score 0 or 1 

• Perform d dimer test and other bloods (see d dimer section below),
• If d dimer is positive, refer to GP Care for ultrasound

D-dimer

D-dimer is now recommended for all patients (NICE NG158 2020) - updated August 2023.

Except;

• Wells score is less than 0
• Pregnant women 
• Individuals who are up to 2 weeks post-operative
• Individuals that have been symptomatic for 2 or more weeks
• Individuals who have a current inflammatory process

Venous d dimer. (Preferred option). Gives a quantitative result, is adjusted for age by the lab and has a less than 1%.risk of a ‘false negative’ result.

If taking a venous d dimer, please also obtain samples for U&Es, LFTs, FBC, CS

Point of care d-dimer. Does not give a quantitative result, can not be age adjusted and has an approximate 2% risk of a ‘false negative’ result

Results

The referring GP will be responsible for;

• Reviewing and informing the patient of the d-dimer results as well as anticoagulating the patient until the d-dimer result is available, and a GP can act on the result.
• Reassessment of the patient if clinical condition changes

Pre-diagnosis anticoagulation

Anticoagulate with oral DOAC treatment (Apixaban or Rivaroxaban) or parenteral treatment (e.g. Enoxaparin) or issue standby scripts for patients:

(Edoxaban should not be used in this circumstance as it requires initial treatment with a parenteral anticoagulant for at least 5 days.) 

• Until the venous d-dimer result is available, and a clinician is able to act on that result

or

• While awaiting the ultrasound scan if it is not available within 4 hours of referral

Any prescriptions for anticoagulation should be kept to the minimum number of days required to cover until the patient has their ultrasound scan (e.g. 7 days).

Information can be found on the links below.

https://www.medicines.org.uk/emc/search?q=%22rivaroxaban%22

https://www.medicines.org.uk/emc/search?q=%22apixaban%22

https://www.medicines.org.uk/emc/search?q=%22Enoxaparin%22

Please also see the BNSSG Formulary: 2.3 Blood clots (Remedy BNSSG ICB)

Post scan management

Negative DVT diagnosis

If the ultrasound results are negative the patient will be advised by the ultra-sonographer to stop their interim anticoagulation and to contact their GP practice for further advice / care as appropriate.

Inconclusive scan result

If the ultrasound result is inconclusive, the patient will see one of GP Care's DVT nurses. Interim anti-coagulation will be stopped between scans but long term or post op anti-coagulation will continue. If necessary, a second ultrasound scan will be arranged for 6-8 days later in accordance with NICE guidelines. The GP will be informed

If incidental findings are seen on the ultrasound, these will be documented on the scan report. Urgent results will be phoned through to the GP Practice within 24hours.

Positive DVT / SVT diagnosis

Patients who have a positive DVT or SVT diagnosis following their ultrasound scan will be seen by one of GP Care’s DVT Nurses to discuss appropriate treatment.

A prescription for 28 days of anticoagulation will be provided.

All patients will then receive a follow up phone call 5-8 days later. Patients with SVT will be discharged back to the care of their GP at this point.

Patients with a DVT will also receive a 3 month (day 90) review .

Unprovoked DVT

Patients who have an unprovoked DVT will be reviewed by one of GP Care’s designated GPs. Further advice on investigation of unprovoked DVT can be found here.

Guidelines

• Venous thromboembolic diseases: diagnosis, management and thrombophilia testing (March 2020) NICE guideline NG158
• https://bnf.nice.org.uk/drugs/rivaroxaban/
• https://bnf.nice.org.uk/drugs/apixaban/

Pregnancy and suspected DVT

The risk of VTE in pregnancy is four to five fold higher than in non-pregnant women of the same age, although the absolute risk remains low at around 1 in 1000 pregnancies. It can occur at any stage of pregnancy but the puerperium is the time of highest risk. The risk is even greater if the patient:

• has a previous personal history of DVT
• has a family history of DVT
• is over 35
• is obese (have a BMI of 30 or more)
• has had a severe infection or recent serious injury, such as a broken leg
• has a condition that makes clots more likely (thrombophilia)
• is carrying twins or multiple babies
• has had fertility treatment
• is having a caesarean section
• is a smoker – get support to stop smoking
• has severe varicose veins (ones that are painful or above the knee with redness or swelling)
• is dehydrated
• has pre eclampsia
• travels for 4 hours or longer

The Wells DVT score and d-dimer testing are not validated in pregnancy and should not be used.

If there is any suspicion of DVT in pregnancy or the post partum period, the patient should be referred to GP Care using EMIS Managed Referrals (Guide for making a managed referral). Ideally patients should be seen within 4 hours of referral.

DOACs are contra-indicated in pregnancy, the post-partum period and in breast feeding mothers.

Enoxaparin is therefore used to anticoagulate. Recommended therapeutic doses in pregnancy are based on booking or early pregnancy weight:

• Up to 50kg - 40mg bd
• 50 to 69kg - 60mg bd
• 70 to 89kg - 80mg bd
• 90 to 109kg- 100mg bd
• 110 to 124kg - 120mg bd
• More than 125kg - refer to obstetric care

In post partum women the dose is as for other patients

• 1.5mg/kg o.d. for uncomplicated patients with low risk of recurrence.
• 1mg/kg bd for patients with proximal thrombosis or risk factors such as obesity, cancer, recurrent VTE
• LMWH can be prescribed during pregnancy and for breast feeding mothers.
• Warfarin is contra-indicated in pregnancy. It may be used after the fifth day post partum or longer for women at increased risk of postpartum haemorrhage. 
• Warfarin can be prescribed for breast feeding mothers.

References:

RCOG - Thromboembolic disease in pregnancy and the puerperium - acute management. (2015)

https://bnf.nice.org.uk/drugs/enoxaparin-sodium/#indications-and-dose

Background Information and Guidelines

CKS Deep Vein Thrombosis  

Deep vein thrombosis (DVT) is the formation of a thrombus (blood clot) in a deep vein, usually in the legs, which partially or completely obstructs blood flow.

DVT has an annual incidence of about 1-2 in 1000 people.

Continuing or intrinsic risk factors include:

• Previous venous thromboembolism.
• Cancer (known or undiagnosed).
• Increasing age
• Being overweight or obese
• Male sex.
• Heart failure.
• Acquired or familial thrombophilia.
• Chronic low-grade injury to the vascular wall (for example vasculitis, hypoxia from venous stasis, or chemotherapy).

 Risk factors that temporarily raise the likelihood of DVT include:

• Significant trauma or direct trauma to a vein (for example, intravenous catheter).
• Hormone treatment (for example hormone replacement therapy or combined oral contraceptive).
• Pregnancy and the postpartum period.

 The most serious complication is pulmonary embolism.

The possibility of DVT should be considered if typical symptoms and signs are present, especially if the person has risk factors. Typical signs and symptoms are:

• Pain and swelling in one leg.
• Tenderness, changes to skin colour and temperature, and vein distension.

 Other conditions which may present with similar signs and symptoms include:

• Physical trauma
• Cardiovascular disorders such as superficial thrombophlebitis and post-thrombotic syndrome
• Other conditions such as ruptured Baker’s cyst, cellulitis, and dependent oedema.

DVT prevention for travellers

https://cks.nice.org.uk/topics/dvt-prevention-for-travellers/#:~:text=The%20annual%20incidence%20of%20DVT,and%20do%20not%20cause%20symptoms.

Differential diagnosis

 https://cks.nice.org.uk/topics/deep-vein-thrombosis/diagnosis/differential-diagnosis/

Resources

(1) Overview | Venous thromboembolic diseases: diagnosis, management and thrombophilia testing | Guidance | NICE

Efforts are made to ensure the accuracy and agreement of these guidelines, including any content uploaded, referred to or linked to from the system. However, BNSSG ICB cannot guarantee this. This guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer, in accordance with the mental capacity act, and informed by the summary of product characteristics of any drugs they are considering. Practitioners are required to perform their duties in accordance with the law and their regulators and nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties.

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