Mild refers to a Villalta score of 5–9, moderate if the score is 10–14, and severe when the score is ≥15, or if a venous ulcer is present, regardless of the Villalta scoring parameters. 10 The Villalta score classifies patients as having or not having PTS, and rates its severity, based on the sum of five venous symptoms and six clinical signs. 9 On the Villalta scale, PTS is defined as a score ≥5, or a venous ulcer present, in a leg with previous DVT. 8 However, the Villalta scale has been validated externally and endorsed by scientific societies. 7 A number of diagnostic and severity scales have been developed for PTS: the Villalta scale, the Ginsberg measure, the Brandjes scale, the Widmer classification, the Clinical–Etiological–Anatomical–Pathological (CEAP) classification and the Venous Clinical Severity Score (VCSS). PTS is primarily a clinical diagnosis based on the presence of typical symptoms and signs of chronic venous hypertension in a patient with a previous DVT, but no objective diagnostic test exists.

PTS is the most common long-term complication after DVT. The aim of this review is to summarise the pathophysiology and risk factors of PTS, highlight various risk reducing strategies for the development of PTS, and discuss future perspectives. 5,6 Therefore, every effort should be made to reduce the risk of PTS when managing patients with DVT.

PTS can occur in up to approximately 50% of patients in the 2 years after DVT, and is resistant to conservative and early thrombus removal therapies. However, PTS is increasingly recognised as an important and common debilitating long-term sequela of DVT, given that failure of natural thrombus resolution can lead to a chronically occlusive post-thrombotic limb. Traditionally, anti-coagulation alone was used to prevent the propagation of DVT and PE and allow natural thrombus resolution. 2 Severe PTS has major socioeconomic consequences, and even mild PTS can have adverse effects on quality of life (QOL). Most commonly, however, DVT can lead to post-thrombotic syndrome (PTS), which affects patients of all ages, and is characterised by leg pain, itchiness, heaviness, swelling, skin discolouration, and, in severe cases, venous ulceration ( Figure 1). 1 DVT is a well-recognised cause of death through pulmonary embolism (PE), and, rarely, limb loss through phlegmasia cerulea dolens. Deep vein thrombosis (DVT) is a common condition estimated to affect approximately 100,000 patients each year in the UK.

Pts 2020