The traditional hemostatic method is mainly to place gauze, bandage, and hemostatic bands on the wound, and press them to stop bleeding. It is effective in most cases, but does not perform well for the bleeding organ in surgery and the wound of complex shape. Since it was first reported as a hemostatic agent in 1940s, gelatin sponge has been widely used by doctor in surgery due to its excellent hemostatic performance.
The tiny porous structure and hydrophilic nature allow it to absorb 40 times its own weight blood. The expanded size due to blood absorption can compress the surrounding tissues and vessels to slow the blood flow. Platelets and fibrin will accumulate near the wound, forming a blood clot and stopping bleeding. The gelatin sponge is usually impregnated with antibacterial and coagulation drugs that are slowly released during the hemostasis process. They effectively speed up coagulation of blood near the wound and inhibit it from being infected. Infection caused by bacteria is a main reason why the wound is difficult to heal.
Wound dressing is often made into gelatin sponge sheet for broken skin hemostasis: it is placed on the wound and pressed down by hand to stanch bleeding. Gelatin sponges are also made into blocks as hemostatic suppository. For example, a sponge inserted into a wound will quickly absorb blood and swell, plugging the wound during a dental extraction. It can also stop visceral bleeding in surgery. Gelatin rarely causes rejection of surrounding tissues, so they do not need to be removed from body. After a period of time, it degrades into small peptides or amino acids that are absorbed in body. Gelatin is usually treated with formaldehyde solution to form more covalent cross-links. It slows down the decomposition of gelatin and prevent it from breaking down before the wound heals.