Prolonged bleeding time as a marker of venous clot lysis during streptokinase therapy

Abstract

Despite their expense and inconvenience, serial ultrasound or venographic examinations are currently the only available methods to assess the efficacy of thrombolysis for deep venous thrombosis (DVT). We therefore tested whether the bleeding time (BT), a simple and inexpensive test, is useful in assessing lytic efficacy and might thus be a valuable adjunct in guiding the dose and duration of the thrombolytic agent. Serial BTs were obtained dally in 16 patients (eight men and eight women, average age 45.5 years, range 19 to 70) receiving streptokinase (SK) for proximal lower extremity DVT ( n = 5), for upper extremity DVT ( n = 10), or for renal vein thrombosis ( n = 1). Duration of treatment averaged 89.9 ± 43.6 hours (range 35 to 198 hours). Clot lysis on ultrasound, venogram, or magnetic resonance imaging (MRI) was defined as: complete (≥90%), moderate (50% to 90%), minimal (<50%), or none. Important (complete or moderate) clot lysis occurred in 9 of 15 patients for whom follow-up studies were available. BT prolongation was defined as greater than 9.5 minutes and, during SK therapy, had a sensitivity of 0.67 and a specificity of 0.67 for important clot lysis. The positive predictive value of prolonged BT for clot lysis was 0.75. Calculated likelihood ratios revealed that a patient with BT prolongation was twice as likely to have important clot lysis rather than minimal or no lysis. These findings suggest that the BT should undergo further investigation as a simple, adjunctive, noninvasive marker of thrombolytic efficacy among DVT patients treated with SK.