Development of lower leg edema in the late afternoon may be associated with decreased blood flow in the leg in women in the luteal phase.

ObjectivesLower leg edema is common in the late afternoon even in healthy individuals and could involve venous blood flows. Women appear more likely to develop lower leg edema, possibly due to the menstrual cycle. However, this phenomenon has not been quantitatively investigated using imaging. This study therefore used sonography to investigate sex-dependent impacts on physiological lower leg edema, in relation to venous blood flows in the legs and the menstrual cycle.MethodsParticipants comprised 54 healthy young adults (30 men, 24 women; mean age, 21 ± 1 years). Thickness of the papillary dermis and thickness and echogenicity of the subcutaneous adipose tissue were measured in the lower leg. Popliteal vein hemodynamics were investigated using Doppler sonography. Values were compared between late afternoon and morning. Each comparison was performed for men, women in the follicular, and women in the luteal phase.ResultsFor women in the luteal phase, papillary dermis and subcutaneous adipose tissue were thicker (median 0.20 mm, interquartile range [IQR] 0.12-0.25 mm vs median 0.33 mm, IQR 0.25-0.35 mm; p < .001 and median 5.0 mm, IQR 4.3-5.5 mm vs median 5.2 mm, IQR 4.5-6.2 mm; p = .013, respectively) and subcutaneous adipose tissue echogenicity was higher (median 66.9 IQR 64.1-70.5 vs median 71.7, IQR 65.0-76.7; p = .007) in the late afternoon than in the morning. The popliteal vein velocity-time integral (VTI) was lower in the late afternoon (median 33.0 cm, IQR 27.3-40.5 cm) than in the morning (median 26.1 cm, IQR 23.5-39.6 cm; p = .043). A significant negative correlation was observed between VTI and echogenicity (r = -0.549, p = .005). These findings were reduced in women in the follicular phase, and absent in men.ConclusionLate-afternoon lower leg edema may be associated with decreased leg blood flow in women, particularly in the luteal phase.