Bleeding and thrombosis in high-risk renal transplantation candidates using heparin

BACKGROUND: Heparin can reduce the risk of renal artery/vein thrombosis in renal transplant patients with hypercoagulable states (HCS), but is associated with a high bleeding risk. Little is known about risk factors for this bleeding risk or the optimal anticoagulation target. OBJECTIVE: To determine factors associated with this bleeding risk and determine the optimal partial thromboplastin time (PTT) ratio. METHODS: We retrospectively reviewed medical records of consecutive adult renal transplant recipients administered heparin for perioperative renal thrombosis prevention (1998-2002). RESULTS: Twenty-eight (3.86%) of 725 consecutive renal transplant recipients received heparin to prevent renal thrombosis. Eighteen patients (64.3%) had clinically important bleeding (14 major bleeding). Patients with and without bleeding were similar in baseline demographic characteristics and overall mean PTT Bleeding occurred at a mean PTT ratio of 2.5 +/- 1, higher than the overall mean in bleeders and nonbleeders (p = 0.001). Among postoperative characteristics, higher maximum PTT (p = 0.052) and prolonged surgical antibiotic prophylaxis (p = 0.053), particularly with cefotetan (p = 0.091), trended toward a significant association with bleeding. Two renal thrombotic episodes occurred, both at PTT ratios <1.5. A PTT ratio of 1.5-1.9 resulted in no thrombosis and ≤4.2% bleeding. CONCLUSIONS: The benefits and risks of therapeutic heparin anticoagulation in renal transplant patients with HCSs were confirmed. Higher PTTs and cefotetan antibiotic surgical prophylaxis could contribute to bleeding. The optimal PTT ratio appeared to be 1.5-1.9 to prevent thrombosis and limit bleeding risk.