This was conceived by Prandoni and introduced in 1994 to clarify the severity of PTS. It is a disease-specific assessment in the evolution of PTS [34]. It is composed of five symptoms (pain, cramps, heaviness, pruritus, and paresthesia) and five signs (pretibial edema, induration of the skin, hyperpigmentation, new venous ectasia, redness and pain during calf compression) in a graded scoring system. Each has a 4-point scale starting from 0 (absent) to 3 (severe) [35]. A score less than five is not diagnostic of PTS. Two consecutive scores of five to fourteen indicate mild to moderate PTS. A score of fifteen or more in two checkups or presence of ulcer on one occasion indicates severe PTS [35]. Villalta score system is simple and easy. It is standardized and validated. It can track the progress of the disease, and it can be applied in clinical settings and in research areas [1].

This is based on the persistence of symptoms or development of new symptoms 6 months after the index DVT. In comparison to the Villalta scale, the Ginsberg measure identifies more severe cases of PTS [35]. The criteria recommended for the Ginsberg measure are as follows [20, 35–37]:

In a comparative study of the two systems, agreement was found to be poor [37]. The proportion of patients diagnosed to have PTS was almost fivefold higher by the Villalta scale than by the Ginsberg measure. It has been concluded that the Ginsberg measure identifies more severe forms of the diseases [37].

This was introduced by the American Venous Forum for assessment of CVD. This has also been used for the severity assessment of PTS [35]. This was validated along with duplex and hemodynamic parameters. VCSS was also compared with the Villalta scale. It has been concluded that VCSS could be useful for the screening of PTS [34, 35].

This is useful in defining any CVD including PTS. It is a static measure, and does not address QoL issues or functional status [1].

In a single-center prospective study of 40 legs in 34 patients with PTS, Lattimer et al. observed that the Villalta scale had a good correlation with VCSS and CEAP classification. But when venous filling index (VFI) was used as a hemodynamic benchmark, the Villalta scale was superior to the other parameters [38].

This is the baseline investigation in most centers. The obstructive changes observed in duplex scan are very characteristic. The deep veins are echogenic, are contracted, and have thick irregular walls. There could be multiple channels, intraluminal webs, and wall thickening. Presence of dilated collaterals indicates obstruction; but their absence does not exclude it [39]. A vein seen one centimeter away from the artery is usually a collateral [39]. Reduced or absent phasicity on duplex scan is an indirect evidence of obstruction. Duplex scan cannot quantify obstruction [9].

Duplex scan is very useful for assessment of reflux. The recommended cutoff value for reflux is 500 ms [39]. Valve closure time and peak reflux velocity have been tried as a measure of quantifying reflux using duplex scan; but they are found to have poor correlation with the severity of reflux [9].

The limitation of duplex scan is that it cannot be used in isolation. It cannot grade reflux properly. It is not sensitive in evaluating the iliac segment [9].

Obstructive pathologies can be diagnosed by hemodynamic tests. But they are not very accurate. The tests include plethysmographic outflow determination and hand-foot pressure differential. These tests are not very sensitive. Femoral venous pressure measurements are more objective. Findings suggestive of obstruction are pre-stenotic pressure rise in supine position more than 2–4 mm of Hg on provocation, slow return to base level (more than 30 s), and a pressure differential more than 2–5 mm of Hg compared to contralateral limb [18].

Reflux can be diagnosed by hemodynamic tests. Several techniques are available. They include air plethysmography (APG), strain gauge plethysmography (SGP), and photoplethysmography (PPG). The refill time is a reflection of reflux, and the use of tourniquet can localize the reflux to different segments. Plethysmography is complementary to duplex scanning.

This is considered to be the most sensitive tool for the diagnosis of vein pathologies [9]. It can pick up both intra- and extraluminal pathologies. The procedure is strongly recommended prior to iliac vein stenting.

This gives an overall assessment of the functional status of the lower limb venous system. The parameters monitored are the drop in the post exercise venous pressure and the recovery time. However, the technique is cumbersome and time consuming and is mostly used as a research tool [40].

A brief review of the various measures useful to prevent the development of PTS is presented below.

The basic principles of treatment are the same as primary CVI as outlined in the earlier chapter. The ulcers of PTS are more resistant and prone for recurrence. It is important to rule out coexisting arterial insufficiency in all these patients.

The treatment strategies are the same as mentioned in the earlier chapter.

CT is still the traditional and primary method of treatment for all venous ulcers including PTS. In the presence of an active ulcer, a supervised program of ambulatory compression therapy using bandages, in dedicated clinics, can produce good outcome. The details and techniques are presented in Chap. 16. CT using compression hosiery is an alternative. The use of below the knee elastic stockings with ankle pressures of 30–40 mm of Hg would minimize the severity of PTS [1]. Intermittent pneumatic compression (IPC) is reported to be useful in the treatment of venous ulcers refractory to previous ambulatory compression alone [42]. A new therapeutic approach in severe CVI with reflux is to use an external valve closure compression pump. This pump can generate intermittent pressure peaks synchronized with calf pump. The device can be specific for the degree of reflux and size of the leg [43]. CT should be continued as long as the risk of ulceration persists.

Several agents are available for improving symptoms and promoting ulcer healing in patients with CVI. But none of them are specific for the treatment of PTS. Two agents which are promising are micronized purified flavonoid fraction (MPFF) and pentoxifylline [1, 44]. Statins are known to protect the endothelium from cardiac events [1]. A randomized trial has proven that rosuvastatin in a dose of 20 mg a day significantly reduces the incidence of DVT [45]. It is not known whether statins will reduce the incidence of PTS [1].

Correction of anatomical defects by open surgery or endovenous interventions has been attempted in treating patients with PTS. Barring stenting all other interventions employed in the treatment of PTS are of secondary importance only [46].