Deep vein thrombosis
The common causes are listed in Table 11.6.
The onset may be ‘silent’ or heralded by pain in the calf, often about 10 days after immobilization for surgery, parturition or an infection. The leg becomes swollen and cyanotic distal to the thrombus. The calf may hurt when handled or if the foot is dorsiflexed (Homan’s sign). Sometimes a pulmonary embolus is the first sign of a silent deep vein thrombosis.
Suitable investigations include venography, Doppler ultrasonography, which can only detect thrombi in large veins at, or above, the popliteal fossa, and 125I-fibrinogen isotope leg scanning.
Treatment is anticoagulation with heparin and later with a coumarin. The value of thrombolytic regimens has yet to be assessed properly. Prevention is important. Deep vein thrombosis after a surgical operation is less frequent now, with early postoperat-ive mobilization, regular leg exercises, the use of elastic stockings over the operative period and prophylaxis with low dose heparin.