Sonographic detection of physiological lower leg edema in the late afternoon in healthy young women

Lower leg edema occurs physiologically in the evening after daytime activity. Various edema-related sonographic findings have recently been reported, but this physiological edema has not been evaluated quantitatively using imaging examinations. The present study investigated whether sonography could detect physiological lower leg edema, comparing measured values between the morning and late afternoon. Diameters of leg veins were also measured as a possible source of leg edema. Subjects comprised 55 healthy young women (mean age, 21±1 years). Edema-related findings such as papillary dermis thickness, subcutaneous adipose tissue thickness, and echogenicity (as estimated in gray-scale using image analysis software) increased in the late afternoon when compared with those in the morning (1.4 [1.1-1.7] mm vs. 1.4 [1.1-1.8] mm, p<0.01; 7.3 [6.0-8.1] mm vs. 7.3 [6.1-8.3] mm, p<0.05; and 37.3 [31.5-39.4] vs. 39.8 [35.7-44.1], p<0.01, respectively). Diameters of leg veins such as the great saphenous vein, small saphenous vein, and dorsal vein of the foot were all reduced toward late afternoon (p<0.01 each). Sonography quantitatively and precisely detected physical changes associated with physiological lower leg edema after daytime activity in healthy young women.