Lymphatic refill in ultrasound and lymphatic washout after lymphaticovenous anastomosis

Abstract Background Lymphaticovenous anastomosis (LVA) drains lymph accumulated in the lymphatic vessels into the veins (lymphatic washout). A method to identify the ideal lymphatic vessels to achieve washout has not been established. This study examined the relationship between lymphatic washout, lymphatic ultrasonographic findings, and surgical outcomes. Methods We reviewed consecutive patients who underwent LVA for lower limb lymphedema between September 2020 and March 2021. Patients who lacked data were excluded. Preoperative ultrasonography was performed to measure the lymphatic diameter. After the probe was pressed against the skin and released, the reaction of the lymphatic vessels was classified as either refilled, crushed, undecidable, or solid. Intraoperatively, whether lymphatic washout was observed or not, was recorded and compared to preoperative findings using the chi‐square test. In 54 limbs from 32 patients, the total number of LVA, number of anastomoses with washout, number of refills detected by ultrasound, and severity of lymphedema were compared with the surgical result (postoperative limb volume change) by multiple regression analysis (49 limbs whose pre‐or postoperative circumference data were lacking or who underwent intensive compression therapy postoperatively were excluded). Results Sixty‐five patients were reviewed. After excluding six patients with missing data, 59 patients (103 limbs) were included. The median patient age was 63 years (interquartile range, 51–76 years). We performed LVA at 217 sites (mean, 2.1 anastomoses per limb). “Refilled” lymphatics were observed at 156 sites (71.6%) and significantly thicker than those classified as “undecidable” ( p = .020 in the lower leg and p < .001 in the thigh). In the thigh, “refilled” lymphatics had a higher rate of a washout than those classified as “undecidable.” In Pearson's correlation coefficient for the surgical result, as the number of washout positive LVA increased, the limb volume tended to decrease postoperatively (correlation coefficient: −0.25). However, multiple regression analysis did not identify any factors that significantly affected the surgical outcomes. Conclusion “Refilled” lymphatic vessels had a higher rate of intraoperative lymphatic washout after anastomosis.