Normal D-dimer levels do not exclude thrombotic complications in trauma patients

Background. Deep venous thrombosis (DVT) and pulmonary embolism (PE) are common complications in trauma patients. These diagnoses can be difficult and expensive to make. Recent studies report that a negative L dimer test excludes thrombotic complications. We questioned the predictive value of a D-dimer test to exclude DVT and PE. Methods. Adult trauma patients admitted March 1999 to March 2001, with an Injury Severity Score greater than or equal to9 and expected length of stay >3 days, were approached for enrollment. Bilateral lower extremity duplex ultrasounds and D-dimer levels were performed within 36 hours of admission, day 3-4, day 7, and weekly until discharge. Results. Twenty-three patients were diagnosed with DVTs, with 18 DVTs detected within the first week of admission. Five DVT patients had normal D-dimer levels. One of three PE patients tested had a normal D-dimer level. The false negative rate for DVT by D-dimer assay was 24%, and the sensitivity was 76%. The negative predictive value for D-dimers was 92%. All false negative D-dimer tests occurred in patients diagnosed with DVT or PE within the 4 days after admission. Conclusion. In the early postinjury phase, a negative D-dimer test does not exclude DVT or PE. However, the negative predictive value of a D-dimer test after the first 4 days from admission rose to 100%. Patients with clinical signs and symptoms of DVT or PE in the immediate postinjury phase should undergo further screening to exclude thromboembolic complications.