Superficial thrombophlebitis refers to inflammation (phlebitis) and thrombosis in subcutaneous veins. The underlying cause may be venous stasis (such as from chronic venous insufficiency or prolonged immobilization), hypercoagulability (as may be seen with pregnancy, the postpartum period, or an underlying malignancy), and/or endothelial injury (from an intravenous [IV] cannula or an infection, termed septic thrombophlebitis).

Superficial thrombophlebitis is more common in women. The greater and the lesser saphenous veins are the most frequently affected veins of the lower extremity, as are the cephalic and basilic veins of the upper extremity. Chronic venous insufficiency is observed in up to one-half of patients with lower extremity superficial thrombophlebitis and may result from venous obstruction and/or venous valvular incompetence. Indwelling catheters are an important cause of upper extremity superficial thrombophlebitis, especially large bore catheters that have been in place for 72 hours or longer.

Mondor disease is rare, benign, self-limiting superficial thrombophlebitis of the chest wall, breast, or penis. Trousseau syndrome is a hypercoagulable state associated with visceral cancer (usually pancreatic) that presents with recurrent migratory thrombophlebitis as well as arterial thrombosis and disseminated intravascular coagulation.

Complications include extension to the deep venous system and sepsis or endocarditis in cases of septic thrombophlebitis.