Deep vein thrombosis (DVT) is the development of a thrombus (blood clot) that completely or partially occludes a deep vein, usually in the legs

Symptoms and signs

• Swelling of limb (arm, calf or leg)
  
  • measure circumference 10 cm below tibial tuberosity and compare with asymptomatic limb
  • difference of >3 cm increases probability of DVT
• Pain and stiffness of affected limb
• Pitting oedema
• Increased skin temperature
• Erythema
• Tenderness
• Mild fever

Pregnancy

• It can be difficult to distinguish symptoms and signs of DVT from normal pregnancy 
  
  • exercise vigilance in pregnant woman – discuss with obstetric registrar/specialist trainee

Complications

• In rare cases, arterial circulation may be severely compromised: 
  
  • severe pain, swelling, cyanosis 
  • rapid development of tense blue oedema (phlegmasia cerulea dolens)
• If patient is an injection drug user, examine for:
  
  • localised infection e.g. erythema or fluctuance suggesting infected clot
  • deep soft tissue infection, abscess at injection site 
  • necrotising fasciitis
  • acute arterial occlusion, and/or myositis
  • systemic infection and septic embolic abscesses e.g. cardiac murmurs suggesting infective endocarditis, sepsis, haemoptysis and cough with purulent sputum

Differential diagnosis

• Ruptured Baker’s cyst
  
  • history of arthritis or trauma to knee
  • swelling behind knee
  • examine for arthropathy and effusion
• Torn calf muscles/damage to Achilles tendon 
  
  • sudden pain in calf following twisting of leg
  • examine for haematoma
  • disruption of tendon indicates severe rupture
• Cellulitis – see Cellulitis guideline
• Fracture
• Oedema (heart failure, hypoalbuminemia, lymphatic obstruction, dependant) 
• Acute Charcot arthropathy
  
  • consider if longstanding diabetic with peripheral neuropathy and/or history of trauma
  • advise reducing weight bearing
  • refer urgently to diabetic nurse, podiatry and orthopaedics

• FBC, INR, APTT, LFTs, and U&E
• If patient is an injection drug user or has signs of infection:
  
  • CRP
  • blood cultures
  • chest X-ray (to exclude septic embolic lung abscesses)
  • ultrasound of groin area (localised collection)
  • echo if murmur, positive blood cultures or chest X-ray suggestive of septic embolic lung abscesses
  • offer testing for blood borne viruses (HIV, HBV, HCV) – see HIV infection testing guideline

D-dimer

•  Raised in many clinical states. See Common causes of raised D-dimer concentration 
  
  • normal D-dimer concentration virtually rules out thrombosis

Common causes of raised D-dimer concentration

• Acute myocardial infarction (MI)
• Chronic subdural haematoma
• Disseminated intravascular coagulation
• Gram-negative bacteraemia
• Leukaemia
• Liver disease
• Metastatic malignancy
• Peripheral vascular disease
• Pregnancy
• Recent surgery
• Renal disease
• Rheumatoid disease
• Sickle cell crisis
• Subarachnoid haemorrhage
• Thrombolytic therapy
• Trauma with pathological thrombosis

• Encourage ambulation
• Elevation of leg when seated
• Simple analgesia (e.g. paracetamol or if inadequate control, co-codamol)

Suspected phlegmasia cerulea dolens (painful blue oedema)

• An uncommon manifestation of massive DVT compromising venous outflow and causing ischemia and manifesting as a painfully swollen blue leg
• Elevate bed foot to 40° and ensure fluid replacement adequate to compensate for extravasation
• Refer urgently to on-call general surgical team

Concomitant infection

• Treat cellulitis or sepsis – see Cellulitis guideline and Sepsis guideline
• If evidence of groin abscess, refer to on-call surgical team
• If evidence of septic pulmonary embolism on chest X-ray, admit to respiratory or infectious diseases ward 
  
  • start treatment for pneumonia, including cover for staphylococcal infection. See Pneumonia guidelines (CAP or HAP)

Symptomatic ileo-femoral DVT

• Suggested by back pain and swelling of entire limb
• Discuss with radiologist (and if pregnant, obstetrician) to consider magnetic resonance venography

Treatment

• Consider catheter guided thrombolysis or mechanical thrombectomy if:
  
  • symptoms of <14 days duration
  • good functional status
  • life expectancy of ≥1 yr
  • low risk of bleeding (for thrombolysis)
• Discuss with interventional radiologist and vascular surgeon
• Do not prescribe elastic graduated compression stockings to prevent post-thrombotic syndrome or VTE recurrence after a proximal DVT

• If no clear precipitating cause for thrombosis, particularly if this is a recurrent event, consider occult malignancy or other cause of thrombophilia
• If patient aged <45 yr with unprovoked DVT, discuss screening for inherited or acquired thrombophilia with haematology consultant 

Screen for cancer

• In all patients with confirmed DVT, chest X-ray, FBC, LFT, calcium and urinalysis 
• Only offer further investigations for cancer to people with unprovoked DVT if they have relevant symptoms or signs 

Outpatient

• Unless symptoms severe, or patient an injection drug user, or requires admission to hospital for reasons other than suspected DVT, treat as outpatient
  
  • ensure form authorising daily injections of dalteparin completed once diagnosis confirmed

Duration of treatment

• Treatment will be continued for 3 months, but duration may be longer if DVT was unprovoked, recurrent or in the presence of cancer or non-modifiable risk factor such as significant immobility

Advice to patient

• Many drugs (including alcohol) interact with warfarin or DOAC 
• To remind their GP, if additional medication is added, that they are taking anticoagulant 
• To inform dentist that they are anticoagulated
• Give advice on extended travel
• Provide PE information booklet

Women of childbearing age (Pregnancy, Pills, Periods)

• Counsel that DOACs and warfarin may be harmful in pregnancy. 
  
  • seek immediate advice if pregnant or trying to conceive
• Anticoagulation may lead to menorrhagia in 70% of women. Apixaban less commonly implicated than warfarin and rivaroxaban
• Do not stop contraception at time of PE diagnosis including combined oral contraceptive pill (COCP) 
• Refer patient to thrombosis clinic to discuss options 
• Anticoagulation negates the ongoing thrombotic risk of the COCP. Stopping COCP may precipitate menorrhagia or lead to pregnancy whilst on a DOAC

Monitoring of warfarin

• Refer to anticoagulant management service for follow-up appointment date 
• Give patient a completed yellow anticoagulation therapy record - see Warfarin for VTE guideline
• Ensure discharge letter includes diagnosis, dosage of warfarin and date of clinic appointment
• If anticoagulation to be monitored by GP, supply GP with written information (on separate sheet, stapled to discharge letter) about:
  
  • indication for anticoagulation
  • proposed duration of treatment
  • proposed target range for INR
  • details of anticoagulation in hospital (give dates, INR results and dosage taken) 

Document

• Document in medical record
  
  • patient has been given written and verbal information about warfarin and has been referred to anticoagulation clinic
  • duration of treatment
  • if definite risk factor identified
  • outpatient investigations
  • monitoring arrangements

Follow-up

• Arrange appointment in 10-12 weeks for appropriate medical clinic
  
  • unless a shorter course of treatment or need for investigation requires earlier follow-up; patients with confirmed DVT remain under the care of duty physician for the day on which diagnosis was confirmed
  • send copy of letter to patient’s GP

• If patient has active cancer, reassess risks and benefits of continuing anticoagulation at 6 months
• After a first proximal DVT without a clear underlying cause or if permanent risk factors present, assess VTE risk and discuss with patient, if anticoagulation should be continued