Gender bias in use of venous ultrasonography for diagnosis of deep venous thrombosis.

Abstract

We observed that ultrasound examinations for deep venous thrombosis (DVT) were more frequently requested for women than for men in our vascular laboratory serving a general outpatient population and referral 774-bed hospital. Because existing literature presents conflicting information about sex differences in occurrence of DVT, we investigated correlation in our population with positive ultrasound study results and risk factors for DVT. In 13 months, 2055 ultrasound examinations for DVT were requested. Of these, 300 patients (15%) were categorized in four subgroups: 75 ultrasonography-negative men, 75 ultrasonography-negative women, 75 ultrasonography (DVT)-positive men, and 75 ultrasonography (DVT)-positive women for risk factor analysis. Women comprised 64% (1311 of 2055) and men 36% (744 of 2055) of ultrasound examinations requested, but men had significantly higher incidence of DVT-positive ultrasonography results (101 of 744 [14%]) compared with women (118 of 1311 [9%]) (p = 0.002 by chi-square testing). There were no significant sex differences in conventional DVT risk factors and no difference in aggregate number of risk factors. The anatomic distribution of DVT was the same in men as in women. Among those having negative ultrasonography results, significantly more outpatient examinations were performed in women (p = 0.018 by t testing). Gender bias exists in use of ultrasonography for diagnosis of DVT. The greater incidence of women undergoing venous ultrasonography is not explained by higher prevalence of DVT risk factors or of higher occurrence of positive ultrasound examination results. Further investigation is needed to determine whether these differences indicate underuse of ultrasonography in men or overuse in women.