▪️CLINICAL PRESENTATION
▫️DVT should be suspected in patients who present with leg swelling, pain, warmth, and erythema. Symptoms are usually unilateral but can be bilateral.
▫️physical examination often unrevealing but legs, abdomen, and pelvis should be examined in patients with suspected DVT.
*larger calf circumference is the most useful finding.
🔺Homans' sign (calf pain on passive dorsiflexion of the foot) is unreliable for the presence of DVT.
▫️Routine laboratory tests (eg, complete blood count, chemistries, liver function tests, coagulation studies) are not useful diagnostically, but may provide clues as to the underlying cause and may influence treatment decisions if DVT is confirmed.
▪️Compression ultrasonography (CUS)
*Compression ultrasonography (CUS) with Doppler is the diagnostic test of choice in patients with suspected DVT.
▫️Proximal vein CUS:
*Proximal vein CUS detects noncompressibility (indicative of thrombus) of the proximal veins (eg, common femoral, femoral, and popliteal veins ).
*technically easier
*A limitation of proximal vein CUS is that, unlike whole leg ultrasonography, the calf veins are not imaged and, therefore isolated distal DVT cannot be detected. However, thrombus in this location(distal) rarely embolizes and anticoagulation is not always necessary in this population.
▫️Whole leg ultrasonography
* it also images the veins in the calf (peroneal, posterior tibial, anterior tibial, and muscular veins), a negative test excludes isolated distal DVT (ie, all DVT).
*limitations: technically more difficult/ operator-dependent.
🔺The iliac vein often cannot be assessed for compressibility and, consequently, these veins are also usually assessed with Doppler imaging or may require computed CT venography.
🔹SUSPECTED FIRST DVT (RISK STRATIFICATION) and Based on the Wells score:
▪️Pretest probability of DVT(Wells Score), High probability: ≥3 points
*Active cancer (treatment ongoing, within 6 months, or palliative).(+1)
*Paralysis, paresis, or recent plaster immobilization of the lower extremities.(+1)
*Recently bedridden >3 days or major surgery within 12 weeks requiring general or regional anesthesia.(+1)
*Localized tenderness along the distribution of the deep venous system.(+1)
*Entire leg swollen.(+1)
*Calf swelling at least 3 cm larger than the asymptomatic side (measured 10 cm below tibial tuberosity.(+1)
*Pitting edema confined to the symptomatic leg.(+1)
*Collateral superficial veins (non-varicose).(+1)
*Previously documented DVT.(+1)
*Alternative diagnosis at least as likely as DVT(eg, Baker's cyst, cellulitis, muscle damage, postphlebitic syndrome, inguinal lymphadenopathy, external venous compression).(-2)
▪️Low probability: Wells ≤0 points:
▫️we suggest that a high- or moderate-sensitivity D-dimer
🔺D-dimer should not be done if it is expected to be positive due to another condition (eg, after recent surgery) (link), instead, these patients can proceed directly to ultrasonography (US).
1. based on the D-dimer result
▫️Normal D-dimer level (<500 ng/mL)~not need further testing.
▫️Positive D-dimer level (>500 ng/mL)~ultrasonography⤵️
2. based on the ultrasonography result:
▫️Negative ultrasonography; If whole leg ultrasonography or proximal CUS is negative for DVT~no need further testing.
▫️Positive ultrasonography~
treat if Proximal DVT is identified
OR Distal DVT is identified (on whole leg ultrasonography) +criteria for the treatment
▪️Moderate probability: Wells 1–2 points
▫️We suggest that a high-sensitivity D-dimer OR proceed directly to ultrasonography without D-dimer testing.
*similar to low probability with some considerations:
▫️Negative ultrasonography:
If whole leg ultrasonography is negative (ie, neither proximal nor
distal DVT is identified)~ no further testing is required.
🔺If proximal CUS is negative~ options include whole leg examination to evaluate the distal veins OR repeat proximal CUS at one week (typically off anticoagulation) to detect possible extension of distal DVT into the proximal veins.