What is a leech and what medical benefit do they belong to?

Leeches are bloodsucking worms with segmented bodies. They belong to the same large classification of worms as earthworms and certain oceanic worms. * Trauma. Large blood clots resulting from trauma can threaten tissue survival by their size and pressure. Blood clots can also obstruct the patient's airway. * Surgical procedures involving reattachment of severed body parts or tissue reconstruction following burns. In these situations it is difficult for the surgeon to make a route for blood to leave the affected part and return to the circulation. The hardest part of reattaching severed extremities like fingers, toes and ears is to reconnect the tiny veins. If the veins are not reconnected, blood will accumulate in the injured area. A similar situation occurs when plastic surgeons move large flaps of skin to replace skin lost to burns, trauma or radical surgery. The skin flaps often drain blood poorly, get congested, and begin to die. Leeches have come to the rescue in both situations.