DVT
Epidemiology
1:1000 overall; 1:100,000 in childhood; 1:100 in elderly; bilateral in 30%; in 6% patients with lower limb
injury; in 15% if immobilised >4/52; 8% annual recurrence rate if unprovoked, 2% if risk factors
Risk Factors
External vessel compression: pregnancy, masses
In vessel wall: trauma, surgery, vasculitis
In blood: stasis (NWB, rigid immobilisation, bed rest >48 hours, travel, external fixation, paralysis, CCF,
major trauma, major surgert, obesity); hormynal (pregnancy, post-partum, OCP, HRT); hyperviscosity;
smoking, nephrotic syndrome; diabetes; cancer (esp adenocarcinoma or metastatic); haematological
problems (eg. Thrombophilia, plasminogen deficiency, platelet problems); hyperhomocystinaemia;
heparins; eldery
Complications
Bleeding, thrombosis, purpura fulminans, multi-organ failure, focal ischaemia, gangrene, oliguria, renal
cortical necrosis, ALI
70% of hospitalised patients are asymptomatic; 1/3 patients asymptomatic overall; examination 75%
sensitivity, 45% specificity;  diameter >2cm (60% sensitivity, 70% specificity), superficial thrombosis,
tenderness, Homan’s sign, fever
Assessment
Well’s Score: -2 for: alternative diagnosis more likely
+1 for: cancer in last 6/12 / immobilization / bed bound >3/7 or major surgery <12/52
tender along veins / entire leg swelling / >3cm  diameter / pitting oedema
collaterals
Low probability:
0
5% incidence of DVT
Moderate probability:
1-2
14% incidence of DVT
High probability:
≥3
50-80% incidence of DVT
Modified Well’s Score: as above but +1 for PMH DVT
DVT unlikely:
≤1
DVT likely:
≥2
Investigations
3-9% incidence of DVT
20-35% incidence of DVT
D-dimer: do if Well’s score ≤1
Level decreased by heparin; normal levels  with age
70-90% sensitivity in DVT’s present <1/52; ELISA 96-98% sensitivity, 55-70% specificity; latex lower but
cheaper and quicker; simpliRED 2nd generation latex 85% sensitivity, 70% specificity; VIDAS 95%
sensitivity, 40% specificity)
False negatives in old DVTs and overwhelming thrombosis; false positives in infection, cancer, tissue
injury, CCF, ACS, CVA, pregnancy, ARF, sickle cell disease, aortic dissection
If low risk and negative: excludes DVT
If mod risk and negative: 1.5-7% risk of DVT
If high risk and negative: 8-37% risk of DVT
USS: do if Well’s ≥2
Loss of vein compressibility; >95% sensitivity and specificity for above knee; 70% sensitivity for below
knee; not good for iliacs
2-point USS – much quicker; >95% sensitivity and specificity done in ED by experienced sonographer;
visualises 99% vessels
Venography: high sensitivity; painful; requires contrast; causes DVT in 1%
MRI: 80% sensitivity for below knee; MRI venography 100% sensitivity and specificity
Elevation; ambulation; analgesia; stockings (wear for 2yrs;  risk of VTE by 50%;  post-thrombotic
syndrome by 50%)
Anticoagulation:  risk of PE to 5%;  recurrent thrombosis in 1st 3/12 by 80-90%; doesn’t  risk of
post-phlebitic syndrome
Mod/high probability: discharge after dose of heparin (40mg enoxaparin OD or 5000iu heparin BD) 
USS within 12 hours
If DVT: continue LMWH until INR therapeutic (minimum 5/7, must overlap warfarin by minimum 4/7)
 continue for 3/12 (life long if thrombophilia; not needed for below knee DVT unless continued risk
factors (eg. Thrombophilia, ongoing POP); propagation occurs in 20% below knee DVT’s therefore do
repeat USS at 3-7/7; if not given heparin, give aspirin
Treat as inpatient if: severe oedema of whole lower limb; thrombus above groin
Management
Thrombolysis: can  incidence of post-phlebitic syndrome, lower incidence of venous ulceration,
complete lysis of thrombus in 30-40%; risk of embolism; indicated if massive iliofemoral thrombosis or
young patient with extensive venous thrombosis <1/52; SKA 250,000iu IV over 30mins  100,000iu/hr
for 24 hours
IVC filter: if high risk from anticoagulation (eg. Mutliple trauma);  rate of PE from 5% to 1% in 1st week
Thrombectomy: if vital function of lower limb threatened
In superficial thrombophlebitis of proximal 1/3 long saphenous vein, extension into deep system must be
excluded by USS, and full anticoagulation is recommended even if there is no DVT (propagation into
deep system will occur in 15%)
If distal superficial thrombophlebitis, do follow up USS in 72 hours and anticoagulate if progresses into
deep system; Otherwise treat superficial thrombophlebitis with RICE, analgesia, NSAIDs; resolves in 34/52