Blood reserves are rarely available in emerging economies. Therefore over 40 Million people cannot undergo surgery. In 2015, 1.2 Million people died of major bleeding during surgery complications. The reusable BLOOP makes it possible to collect and clean the patients leaking wound blood and give it back in to the bloodstream during surgery BLOOPs simple function is based on a common siphon principle. BLOOP allows blood to flow uphill without pumps. In the beginning a blood thinning medicine inside the vessel flows down the tube. That creates gravity which absorbs the wound blood. The blood is filtered and discharged in a blood bag at a level lower than the surface of the blood filled wound. As soon as the blood bag is filled, it will be replaced with an empty one. The first unit of collected blood can be already given back to the patient. Depending on the financial and infrastructural development of medical facilities, the product can be extended to a high-end version.