Incidence of venous thromboembolism after spine surgery.

Background: The incidence of venous thromboembolism (VTE) has varied among studies of patients undergoing elective spine surgery. This may be because of differences in prophylaxis for VTE and differences in methods of observation. Furthermore, some studies have reported symptomatic deep vein thrombosis (DVT) or pulmonary thromboembolism (PE), whereas others have included asymptomatic DVT or PE, making comparisons difficult. Therefore, the objective of this study was to determine the incidence of symptomatic and asymptomatic PE in patients undergoing elective spine surgery and to evaluate therapeutic methods for these conditions.

Methods: The subjects were 1975 patients who underwent spine surgery in our hospital from 1990 to 2011. Patients treated from January 1990 to November 1996 (n = 541, Group A) did not receive prophylaxis whereas those treated from January 2000 to February 2011 (n = 1,434, Group B) used a foot pump during and after surgery and subsequently wore elastic stockings. All subjects in Group A began ambulation ≥2 weeks after surgery whereas those in Group B began to walk earlier-within 3 days for patients who underwent decompression and within 1 week for those treated with fusion. From June 2010 to February 2011, contrast-enhanced computed tomography (CT) was performed 1 week after surgery for 100 patients to evaluate the presence of DVT and PE. Since March 2004, D-dimer was measured 1 week after surgery and patients with a level ≥10 μg/mL were followed up.

Results: The incidence of symptomatic PE was significantly higher in Group A than in Group B (8/541, 1.5% vs. 3/1,434, 0.2%). In 3 patients in Group B, PE developed within 1 week postoperatively and D-dimer values at onset were ≤10 μg/mL. In the 100 cases examined by contrast-enhanced computed tomography (CT), asymptomatic PE and VTE were detected in 18 and 19%, respectively. The D-dimer level 1 week after surgery was ≥10 μg/mL in 105 of 841 patients; however, none of these patients had clinically symptomatic VTE for at least 3 months postoperatively.

Conclusions: Mechanical prophylaxis and early ambulation may be effective in reducing the incidence of symptomatic PE after spine surgery. Asymptomatic PE developed in 18% of patients who received mechanical prophylaxis, but the incidence of symptomatic PE was only 0.2%. Prompt diagnosis and treatment are required for patients who develop symptomatic PE.