Phlegmasia cerulea dolens indicates a massive venous thrombosis, in which the leg is often blue. Pelvic vein, mesenteric vein, portal vein, renal vein, and jugular-mesenteric vein thromboses are discussed elsewhere in The Manual. Endothelial injury can expose collagen, causing platelet aggregation and tissue thromboplastin release that, when stasis or hypercoagulability is present, trigger the coagulation mechanism. Septic phlebitis is possible whenever a septic process is present in the extremity distal to or at the level of the venous obstruction. Septic thrombi may form separately from the infectious focus or may occur in contiguity with the inflammatory area as part of a cellulitis.
Most venous thrombi begin in the valve cusps of deep calf veins.
Antiplatelet drugs, despite intensive study, have not proved effective for prevention. Symptoms and Signs Symptoms of acute thrombophlebitis arise over hours to 1 or 2 days. The disease is usually self-limited and lasts 1 to 2 wk, after which the acute process subsides and painful symptoms disappear. DVT involving the popliteal, femoral, and iliac segments may be tender, with a hard cord palpable over the involved vein in the femoral triangle in the groin, medial thigh, or popliteal space. With iliofemoral venous thrombosis, dilated superficial collateral veins usually appear over the leg, thigh, and hip areas and lower abdomen.