Superficial Thrombophlebitis

Procedure

Patient lying on their back with the knee straight. Gently and passively dorsiflex the ankle. Do not squeeze or massage the calf.

Positive Finding

Pain in the calf or behind the knee as the ankle is dorsiflexed.

Interpretation

Not a test for superficial thrombophlebitis. It was used historically for DVT and does not reliably separate DVT from other calf problems. DVT is often found alongside superficial thrombophlebitis, so refer for ultrasound rather than relying on this sign.

Procedure

Look along the course of the superficial veins (great and small saphenous veins, and any varicose veins) and gently feel along them, comparing with the other leg. Mark the upper end of any hard segment with a pen.

Positive Finding

A firm, tender, cord-like vein with redness and warmth along its course.

Interpretation

The typical finding in superficial thrombophlebitis. Ultrasound is still needed, because clot can spread into the deep veins, and clot near the groin junction needs blood-thinning treatment. Refer for same-day medical review, especially if the cord is above the knee, is long, or there is no varicose vein to explain it (which raises the question of an underlying cause such as cancer or a clotting disorder).

Procedure

Patient lying down. Mark a point 10 cm below the tibial tuberosity on both legs and measure the calf circumference at the mark with a tape measure.

Positive Finding

The symptomatic calf is more than 3 cm larger than the other.

Interpretation

Superficial thrombophlebitis causes local swelling along the vein. Swelling of the whole calf suggests DVT, cellulitis or another cause, and more than 3 cm difference is part of the Wells score for DVT. Refer for ultrasound.

Procedure

Score the Wells criteria for DVT. Each of the following scores +1: active cancer (treatment ongoing, within the previous 6 months, or palliative); paralysis, paresis, or recent plaster immobilisation of the lower limb; recently bedridden for 3 days or more, or major surgery within the previous 12 weeks; localised tenderness along the distribution of the deep venous system; entire leg swollen; calf swelling more than 3 cm greater than the asymptomatic side (measured 10 cm below the tibial tuberosity); pitting oedema confined to the symptomatic leg; collateral non-varicose superficial veins; previously documented DVT. Subtract 2 points if an alternative diagnosis is at least as likely as DVT.

Positive Finding

Two-tier interpretation (Wells 2003): score 2 or more = "DVT likely"; score 1 or less = "DVT unlikely". Original three-tier version: 0 or less = low, 1-2 = moderate, 3 or more = high probability.

Reference: Wells PS, Anderson DR, Rodger M, et al. N Engl J Med 2003;349(13):1227-35; PMID 14507948

Interpretation

Wells is a pre-test probability tool, not a diagnostic test — it directs investigation, it does not confirm or exclude DVT. In the "DVT unlikely" group (score 1 or less) a negative high-sensitivity D-dimer makes DVT sufficiently improbable to withhold imaging; every other combination requires compression ultrasound. Specific to superficial thrombophlebitis: concurrent or subsequent DVT is common, so a low Wells score does NOT remove the need for duplex ultrasound where thrombus is extensive or approaching the saphenofemoral junction. (A previous version of this page assigned fabricated point values — 3 points for deep-vein tenderness, 2 for whole-leg swelling, 3 for calf asymmetry. Every Wells criterion scores 1 point; only the alternative-diagnosis item scores -2. Those values also contradicted the deep-vein-thrombosis page in this same dataset.)

Procedure

Inspect both legs standing and lying: redness, swelling and visible veins. Mark the edges of any redness with a pen so change can be tracked.

Positive Finding

A red, warm streak along the line of a vein, often over a varicose vein.

Interpretation

A red streak along a vein suggests superficial thrombophlebitis. A spreading patch of redness without a cord, especially with fever, suggests cellulitis; red streaks running up the leg from a wound suggest lymphangitis. All need medical review; fever, rapidly spreading redness or a very unwell patient needs same-day or emergency care.

Procedure

Ultrasound scan of the superficial and deep leg veins, done by a sonographer.

Positive Finding

A superficial vein that will not compress, with clot inside. The scan also measures how close the clot is to the deep veins and whether it has spread into them.

Interpretation

Confirms the diagnosis, measures the length of the clot and its distance from the groin junction, and checks for DVT. These findings decide whether blood-thinning treatment is needed. It is the test to refer for.