Session X - Pelvis

The Effect of Screening for Deep Vein Thrombosis on the Prevalence of Pulmonary Embolism in Patients with Fractures of the Pelvis or Acetabulum: A Review of 973 Patients

Adam J. Starr, MD; Drake S. Borer, MD; Ashutosh V. Rao, MD; Shelly Whitlock, CCRA; Charles M. Reinert, MD; Paul Weatherall, MD; Julie Champine, MD; Alan L. Jones, MD; William Frawley, PhD; Daniel Thompson, MD; Daniel Weatherall, MD; University of Texas Southwestern Medical Center, Dallas, Texas, USA

Purpose: We studied the effect of screening for deep vein thrombosis (DVT) on the prevalence of pulmonary embolism (PE) in patients with fractures of the pelvis or acetabulum. The study compared the prevalence of PE in a time period without screening to the prevalence seen during a time period when an aggressive screening protocol was in place.

Methods: This study was conducted at a university medical center affiliated with a level I trauma hospital. All patients were cared for at the same institution by the same team of orthopaedic trauma surgeons and general surgery trauma surgeons. Prophylaxis for DVT was the same for both groups. Data for the study was obtained from a prospectively collected trauma registry. Experienced trauma registry nurses performed trauma coding. All patients with closed fractures of the pelvis or acetabulum were identified. Ages, mechanism of injury, Injury Severity Score (ISS), and hospital length of stay were recorded. The use and method of screening for DVT was recorded. Pulmonary emboli were noted, and the method of diagnosis of PE was recorded. Deaths were tallied, and all autopsy records were reviewed to discover any evidence of PE in patients who died. In cases in which autopsy reports were cursory, medical records were reviewed to see if clinical suspicion of PE existed during the patient's hospital course. From November 1, 1997 though November 31, 1999, an aggressive screening protocol for DVT was used that employed both ultrasound and magnetic resonance venography. From January 1, 2000 through December 1, 2001, no screening for DVT was used. The information gathered for the 1997 through 1999 time period was compared statistically to that gathered for the 2000 through 2001 period.

Results: During the 1997 to 1999 time period, 486 patients with fractures of the pelvis or acetabulum were treated; during the 2000 to 2001 time period, there were 487. There was no significant difference between the two groups with regard to age (P = 0.65), ISS (P = 0.09), hospital length of stay (P = 0.2), or mortality rate (P = 0.65). In the 1997 to 1999 time period, when an aggressive DVT screening protocol was in place, 10 patients (2%) were diagnosed with PE; 3 (0.6%) died. All but two of the patients who were diagnosed with PE had undergone screening for DVT, and none of the screening tests were positive. In the 2000 to 2001 time period, when no screening for DVT was done, seven patients (1.4%) were diagnosed with PE, and none died. There was no significant difference between the prevalence of PE seen in 1997 to 1999 and that seen in 2000 to 2001 (P = 0.48). The sample size of 973 patients was sufficient to detect a difference of 4% in the rate of PE (a rate of 2% vs. a rate of 6%) with an 85% power, with a type I error of 0.05.

Discussion: Prophylaxis and screening for thromboembolic disease are controversial. The EAST practice management guidelines for prevention of venous thromboembolism recommend screening for deep vein thrombosis in trauma patients because ". . .serial duplex ultrasound imaging of high-risk asymptomatic trauma patients. . . may be cost-effective and may decrease the incidence of PE."¹ EAST guidelines also recommend magnetic resonance venography because it ". . .may have a role in diagnosing acute DVT in the trauma patient, especially with clots in the calf and pelvis (areas where venography and ultrasound are less reliable)." However, there are no published guidelines regarding the best time to screen, the best screening test, or the best method of prophylaxis. Our finding of negative screening tests in patients who later developed PE raises the possibility that we screened at the wrong time. However, it is unclear which time would have been better. Daily screening is impossible, and serial screening is impractical in multiply injured patients. Since discontinuation of screening had no apparent effect on the prevalence of PE in our study population, it is impossible to justify screening.

Conclusion: Discontinuation of screening for DVT did not change the rate of PE in our patients with closed fractures of the pelvis or acetabulum. Overall rate of PE was 17 of 973 patients or 1.7%. The overall rate of fatal PE was 3 of 973 patients or 0.31%.

1. Rogers FB, Cipolle MD, Velmahos G, Rozycki G, Luchette FA: Practice management guidelines for the prevention of venous thromboembolism in trauma patients: the EAST practice management guidelines work group. J Trauma. 2002; 53:142-64.