- INTRODUCTION: Low levels of plasminogen activator inhibitor type 1 (PAI-1) have been associated with increased risk for perioperative bleeding in some case reports. The aim of this study was to investigate prospectively whether low PAI-1 activity increases the risk for perioperative bleeding in patients undergoing transurethral resection of prostate, an organ with high fibrinolytic activity. PATIENTS AND METHODS: 62 patients with benign prostatic hyperplasia planned for transurethral resection were included. Blood samples for PAI-1 were taken together with other routine preoperative blood samples 1week before surgery but analyzed after the hospitalization. The intraoperative blood loss was determined by measuring the amount of hemoglobin in the irrigating fluid. The postoperative blood loss was estimated from calculations of hemoglobin mass (Hb mass), which is a product of hemoglobin concentration and blood volume. Hb mass was calculated before surgery and on the day of discharge, and was adjusted for intraoperative blood loss and transfused Hb mass. Bleeding complications were defined as re-operation due to bleeding, more than 40ml intraoperative bleeding/g resected prostatic tissue or postoperative blood loss corresponding to more than 100g of hemoglobin. RESULTS: Bleeding complications were observed in 3 of 4 (75%) patients with low PAI-1 levels, defined as <1U/ml, and in 16 of 58 (28%) patients with PAI-1 levels >1U/ml (P=0.082). After adjustment for resection time, resected prostatic mass and systolic blood pressure this became borderline significant (odds ratio 11.8; 95% confidence interval 1.00-139; P=0.05). CONCLUSION: Low PAI-1 activity may contribute to the risk of bleeding after transurethral resection of the prostate.