Introduction: Ultrasound-guided foam sclerotherapy (UGFS) is an alternative and supplementary method for endovenous thermal ablation (EVTA) to treat incompetent saphenous reflux (ISR) and branch varicose veins (BVV).[1] The long-term result is not as satisfactory as EVTA, even while administered by catheter-directed method with or without tumescent local anesthesia.[2,3,4] Combined high ligation(HS) of sapheno-femoral junction(SFJ)/ sapheno-popliteal junction (SPJ) and reversed catheter-directed foam sclerotherapy (rCDFS) to treat ISR is an idea to assure SFJ/SPJ closure, avoid foam leaking into deep vein and enhance foam-endothelium interaction to improve safety and surgical results in less invasive and lower cost way. Midterm sonographic changes of target saphenous veins (TSV), clinical severity improvement and re-intervention rate are our concerns. Methods: From Jan. 2015 to Nov. 2018, 37 patients, 38 limbs treated with HS+rCDFS were retrospectively reviewed. The TSVs, CEAP severity, life quality scores, presence of venous leg ulcers (VLU), previous procedures for ISR or BVV, ongoing surgical procedures and following procedures were recorded. All enrolled patients were called back for re-evaluation of CEAP severity, life quality scores and VLU healing. The sonographic changes of TSV and BVV were focused. Results: 37 patients, 70.3% female, aged 29-85(mean 62.4), received HS+rCDFS because of unsatisfactory results of previous interventions (UGFS 21%, others 22.2%) or reluctant to EVTA. The severity above C4a was 76.3% (figure 1), including 26.3% with VLU. The TSVs included 30 great saphenous veins(GSV), 1 anterior accessory great saphenous vein (AAGSV) and 7 small saphenous veins (SSV). 71.1% surgeries were proceeded under local anesthesia. 23.7% surgeries combined with miniphlebectomy and 28.9% with sclerotherapy to BVV and 10.5% with sclerotherapy to reticular/spider veins. 63.2% patients needed following sclerotherapy, 18.4% needed following miniphlebectomy. 70.3% patients were followed from 57 to 1316 (mean 248) days. 76.9% TSVs were fibrotic or sealed. There were 4 small caliber recanalization, 1 large caliber recanalization(LCR), 1 neovasculization and 1 collateralization.(table 1) The VLU healing rate was 100%. The mean AVVQ and VCSS were 2.4, 1.9 respectively. There was one re-intervention for LCR with 1% polidocanol microfoam, Varithena. Conclusion: The severity of this series of patients was high but HS+rCDFS still permitted satisfactory midterm results to treat de novo or relapsed ISR and BVV and achieved 100% VLU healing, not inferior to EVTA or open saphenous vein stripping. The follow-up sonographic findings were surprisingly well without evident neovasculization as expected. Only 4% significant collateralization or LCR might need re-intervention. Disclosure: Nothing to disclose