Occult proximal deep vein thrombosis: its prevalence among patients admitted to a rehabilitation hospital.

This study was designed first to determine the prevalence of occult proximal deep vein thrombosis (DVT) in stroke patients admitted to rehabilitation hospital using the technique of impedance plethysmography (IPG), and second, to identify clinical findings which may be indicators of an increased risk for the development of proximal DVT. Impedance plethysmography was performed on 105 consecutive stroke patients within one week of admission to our hospital. It was found that 34 out of 100 patients with adequate studies had abnormal IPG, two out of the 34 had known DVT, leaving 32 out of 98 with undiagnosed DVT (19 on the paretic side alone, nine bilateral, and four on the nonparetic side). Using logistic regression analysis, it was determined that profound weakness, male gender, interval between the stroke and IPG, edema, and leg hyperpigmentation were independently associated with positive IPG. Since IPG has a high positive predictive value for proximal DVT, one must assume that most of our patients with positive IPG have proximal DVT. Routine screening of stroke patients for DVT seems indicated and probably should include noninvasive venous studies such as serial IPG. The most efficient screening protocol needs to be determined.