Change of the Lymphatic Diameter in Different Body Positions

Background: Until now, lymphatic ultrasound was performed with the patients in the prone position. The aim of this study was to evaluate the change in the lymphatic diameter in different body positions. Methods: We performed a retrospective study. We performed indocyanine green (ICG) lymphography and lymphatic ultrasound as a pre-operative examination for lymphaticovenous anastomosis (LVA). ICG was injected at three lymphosomes per limb (the saphenous lymphatics, lateral thigh lymphatics, and lateral calf lymphatics). For the lymphatic ultrasound, a commonly used ultrasound device with an 18 MHz linear probe was employed. We measured the lymphatic diameter in the designed LVA sites in prone, sitting, and upright position. Results: We investigated 61 limbs of 31 female patients with lower limb lymphedema. The mean age was 62.0 (range: 42–86) years. We measured the lymphatic diameter at 78 sites in the thigh and 76 sites in the lower leg. In the thigh, the mean lymphatic diameters in the supine and upright positions were 0.43 ± 0.02 mm and 0.40 ± 0.02 mm, respectively, with no significant difference ( p  = 0.10). In the lower leg, the mean lymphatic diameters in the supine, sitting, and upright positions were 0.68 ± 0.04 mm, 0.63 ± 0.04 mm, and 0.63 ± 0.04, respectively. A significant decrease was noted between the supine and sitting positions ( p  = 0.02). Conclusions: The lymphatic diameter in the lymphedematous lower limbs tended to decrease when the patients changed their body position from supine to the sitting or upright positions.