Aquitain DVT Score

What is the Aquitain DVT score?

The Aquitain (often referred to as the Constans outpatient score) is a clinical prediction rule used to estimate the probability of lower-limb deep vein thrombosis (DVT) in ambulatory patients.

It supports structured diagnostic pathways by stratifying patients into low, intermediate, or high clinical probability groups.

How is the score calculated?

• Male sex: +1
• Paralysis or lower-limb immobilisation: +1
• Bed rest > 3 days: +1
• Increased lower limb volume (swelling): +1
• Unilateral lower limb pain: +1
• Alternative diagnosis at least as plausible as DVT: −1

Interpretation

• Score ≤ 0: Low clinical probability.
• Score 1–2: Intermediate clinical probability.
• Score ≥ 3: High clinical probability.

Next steps (general guidance)

This tool supports clinical judgment and should be used within local protocols. In many pathways, clinical probability guides the use of D-dimer testing and ultrasound.

• If clinical probability is low or intermediate, a negative high-sensitivity D-dimer may exclude DVT without ultrasound in appropriate patients.
• If D-dimer is positive (or if D-dimer is not available), venous ultrasound is generally indicated.
• If clinical probability is high, proceed directly to complete venous ultrasound; D-dimer is generally not recommended for ruling out DVT in this group.
• If an initial proximal ultrasound is negative but suspicion remains high, repeat or complete ultrasound within about 7 days (depending on local protocol).