A doctor performs a skin graft operation on a self-immolation victim in Afghanistan.

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Types of Skin Grafts

In all skin graft procedures, skin must be removed from a donor site and attached to the wounded area. The preferred source of the donor skin is the patient himself. This procedure is called an autograft. Since the body's immune system will ultimately reject foreign skin, autografts are the best option for long-term treatment.

In some cases, the patient might be too sick or injured for doctors to immediately perform an autograft. In that case, doctors may place a temporary skin covering on the affected area to cut down on the chance of infection and buy time until the patient regains his or her strength.

When skin is used from another human (usually a cadaver), it's called an allograft. Allografts can last seven to ten days before the body rejects them [source: WCI]. Xenografts are temporary skin coverings harvested from animals, usually pigs. They only last three to five days [source: BCM]. In some cases, the injury is superficial enough that the patient doesn't need an autograft. The allograft or xenograft can provide enough protection to allow the skin to regenerate on its own.

In cases where an autograft is necessary, there are three major types to choose from: split-thickness grafts, full-thickness grafts and composite grafts. The main criteria for choosing which method to use is the depth of the patient's skin loss. Split-thickness grafts are for the shallowest wounds, or those that affect only the epidermis and part of the dermis. They are called split-thickness grafts because the doctor removes only a few layers of skin from the donor site.

Full-thickness grafts require that all three skin layers -- epidermis, dermis and hypodermis -- be removed from the donor site. Full-thickness grafts are often used in cases where the cosmetic appearance of the injured area is very important, like the face. Full-thickness grafts include hair follicles, sweat glands and blood vessels that allow the graft area to look and function more normally. Split thickness grafts, since they lack underlying glands and blood vessels, tend to look flat and discolored.

A composite graft is for wounds that include bone, tendon, cartilage or the loss of muscle. In the case of a nose reconstruction, for example, the surgeon would need to harvest a composite graft that includes supportive cartilage tissue along with the skin layers.

An exciting new alternative to autografts is lab-generated skin, but we'll talk more about that later. Right now, we're going to walk through the difficult skin graft surgical procedure.