BACKGROUND: Autologous fat grafting (AFG) has become a common method of contour modulation of breasts after post-mastectomy implant reconstruction since the lift of the ASPS ban in 2009. Standard methods involve multiple tedious steps: harvesting, collection (with various possible manipulations) and finally reinfusion to the recipient site, most frequently via manual syringe.1,2 We developed a novel technique condensing these steps into one closed-loop system. In this innovative method3,4 we used a continuous flow pump to reinfuse fat to the breast. Del Vecchio also recently showed safety and efficiency with this method.5 METHODS: We conducted a retrospective cohort review of patients receiving AFG for breast contouring either by the syringe or closed-loop method by a single surgeon. Time to infuse fat, complications, and outcomes were analyzed. The cohort included 19 syringe AFG procedures (34 breasts) and 25 closed-loop procedures (41 breasts) between 2013 and 2018. Both short term (infection, explant) and long-term complications (granulomas, cysts, biopsy) were analyzed. RESULTS: Average infusion time was 15 minutes (4–30) for the closed-loop technique. Clinical follow-up times ranged from 28 to 161 weeks (mean=88) for syringe and 0 to 130 weeks (mean=32) for the closed-loop method. There were 2 major and 6 minor complications out of 34 breasts in the syringe method (5.5%, 16.6%, overall 23.5%) versus 1 major and 5 minor complications out of 41 breasts in the closed-loop method (2.4%, 12.1%, overall 14.6%) [p-value major=0.49, minor=0.58, overall=0.33]. Syringe complications included 2 granulomas and 1 cyst (8.8%) while the closed-loop complications included 2 granulomas (4.9%) [p-value=0.50]. Average total volume transferred was 262cc (60–850) for syringe, and 334cc (80–795) for closed-loop method. Infusion rate for the closed-loop method ranged from 100 to 250 mL/min, most consistently at 125 ml/min. CONCLUSION: The study suggests the closed-loop technique significantly decreases time of fat transfer to an average of 15 minutes, a trend towards decreased overall complications, though not statistically significant, and good subjective fat retention beyond 12 months. This suggests the closed-loop method is safe, effective, and significantly decreases operating time. We continue to collect patients in the closed-loop cohort and are also analyzing variation in adipocyte viability between the two methods. REFERENCES: 1. Coleman SR, Saboeiro AP. Fat Grafting to the Breast Revisited: Safety and Efficacy. Plastic and Reconstructive Surgery. 2007;119(3):775–785. doi:10.1097/01.prs.0000252001.59162.c9. 2. Delay E, Garson S, Tousson G, Sinna R. Fat Injection to the Breast: Technique, Results, and Indications Based on 880 Procedures Over 10 Years. Aesthetic Surgery Journal. 2009;29(5):360–376. doi:10.1016/j.asj.2009.08.010. 3. Hayssen H, Hagarty SE. A Novel Closed-Loop Autologous Fat Grafting Technique for Breast Reconstruction. Annals of Plastic Surgery. Vol 78, April 2017. 4. US and International Patent Applications. (US20170312403) Simple Closed Loop System for Direct Harvest and Transfer for High Volume Fat GraftingApril 2016 and (WO2017189918) A CLOSED LOOP SYSTEM FOR DIRECT HARVEST AND TRANSFER FOR HIGH VOLUME FAT GRAFTING, PCT Patent Applications April 2016, April 2017. 5. Del Vecchio D, Wall S Jr., Expansion Vibration Lipofilling: A New Technique in Large-Volume Fat Transplantation. Plastic and Reconstructive Surgery. 2018 May;141(5):639e-649e. doi:10.1097/PRS.