Unexpected hematoma due to heparin prophylaxis in transverse rectus abdominis musculocutaneous flap reconstruction

Prophylactic heparin came into widespread use after low dose or mini-dose heparin (low dose unfractionated heparin [LDUH]) was found to be effective in significantly reducing the risk of deep vein thrombosis (DVT) and pulmonary embolism, without major bleeding complications. This regimen is the standard for comparison with other methods, and it is the mainstay in moderate and high risk general surgery patients (1). It is thought to work because heparin concentrations that are too small to block the extension of preformed thrombi can prevent the activation of clotting factors that are high in the intrinsic clotting cascade from leading to thrombin production and thrombus formation. Usually, 5000 U heparin is given subcutaneously 2 h before surgery, and 8 to 12 h after surgery for five to seven days. Although it is thought to be very safe, low dose heparin prophylaxis increased clinically minor surgical bleeding from 3.8% to 5.9% in patients or control groups, as shown by a meta-analysis of multiple trials (2). Other pharmacological venous thrombosis prevention regimens consist of adjusted dose subcutaneous heparin, ultra low dose heparin, heparin or dihydroergotamine, low molecular weight heparin and heparinoids, mini-dose heparin, low or moderate dose perioperative warfarin and dextran 40/70 Da. In addition, venous flow accelerations, preoperative electric calf stimulation, graded pressure stockings and external intermittent calf or thigh compression have been used to decrease stasis. The regimen used in the present study for DVT prophylaxis in patients undergoing breast reconstruction consisted of a preoperative subcutaneous injection of 5000 U heparin, followed by 5000 U heparin injected twice daily until the patient was ambulating well. Traditionally, common sites