A large DVT causes limb swelling and discolouration
The worst form of DVT can cause gangrene of the toes (phlegmasia caerulea dolens)
Although much talked about, serious DVT (traveller's thrombosis) after a long haul flight is quite rare
It is important to treat DVT effectively to reduce the liklihood and severity of post phlebitic problems (pain, swelling, skin discolouration and ulceration)