Utility of an initial D-dimer assay in screening for traumatic or spontaneous intracranial hemorrhage

Objective: To evaluate the sensitivity of a D-dimer assay as a screening to ol for possible traumatic or spontaneous intracranial hemorrhage. If adequa tely sensitive, the D-dimer assay may potentially permit omission of a more expensive computed tomography (CT) scan of the head when such hemorrhage i s clinically suspected. Methods: Prospective, consecutive, blinded study of patients (age > 16 years) requiring a CT scan of the head for suspected in tracranial hemorrhage over a five-month period at a university, Level I tra uma center. All study patients had a serum D-dimer assay obtained prior to their CT scans. Sensitivity and specificity, with 95% confidence intervals (95% CIs), of the enzyme-linked immunosorbent assay (ELISA) D-dimer assay f or the detection of intracranial hemorrhage were calculated. Results: Of th e 319 patients entered in the study, 25 (7.8%) had a CT scan positive for i ntracranial hemorrhage. Patients with intracranial hemorrhage were more lik ely to have a positive D-dimer assay (chi-square = 13.075, p < 0.001). The D-dimer assay had 21 true-positive and four false-negative tests, resulting in a sensitivity of 84.0% (95% CI 63.7% to 95.5%) and a specificity of 55. 8% (95% CI 55.5% to 55.9%). The four false-negative cases included one smal l intraparenchymal hemorrhage, one small subarachnoid hemorrhage, one moder ate-sized intraparenchymal. hemorrhage with mid-line shift, and one large s ubdural hematoma requiring emergent surgery. Conclusions: Due to the catast rophic nature of missing an intracranial hemorrhage in the emergency depart ment, the D-dimer assay is not adequately sensitive or predictive to use as a screening tool to allow routine omission of head CT scanning.