Complications

Pulmonary embolism (PE) is an immediate and potentially fatal complication of DVT that is precipitated by fragmentation of the organising thrombus

• most common from the larger veins
• a 10% incidence of symptomatic PE from an untreated proximal DVT. If left untreated mortality from such a PE is 18–30% (1)

Phlegmasia cerulea dolens or venous infarction of the leg may also occur if the thrombosis is extensive.

Later complications result from re-canalisation of the organised thrombus. This may fail causing the affected vein to remain partially or fully occluded, or more frequently, damages the valves in the process.

• in either case, chronic venous insufficiency ensues. Deep venous drainage is impaired and ankle venous pressure remains high despite a functioning muscle pump. Blood is forced into the superficial veins causing varices, and more importantly, disruption of the normal vascular dynamics of the skin and subcutaneous tissues. The effects of these changes define the post-thrombotic limb

Recurrence of DVT (1):

• more than 20% of DVTs recur within 5 years
• the risk of this is higher if there are underlying risk factors

Reference:

1. MeReC Bulletin (2003); 13(4):13-16.