The most common cause of skin slice graft failure is hematoma or seroma, followed by poor fixation, infection, inappropriate selection of indications and grafting method, and excessively low health and nutritional status. In addition, complications in the donor area should be avoided. 1. Hematoma or seroma Subcutaneous hematoma is the most common reason for failure of fresh wound implant. It is mainly due to imperfect hemostasis, or improper dressing, or uneven pressure. If it is difficult to stop the bleeding of the wound when implanting the skin, the skin piece can be temporarily covered with the wound and compressed for 5~10 minutes, and the bleeding can be stopped. Then lift the skin piece and remove the trauma and the small blood clots on the skin piece. During the suturing of the skin piece, attention should be paid to pressing the skin piece on the wound surface to avoid accumulation of blood under the skin piece. Consider placing drainage strips in the low position (under the skin slice) before dressing, and remove them at 24 hours. When dressing the implant area, it is still necessary to maintain anesthesia and reduce patient agitation until the dressing is fixed, then the hematoma can be reduced. If coagulation disorder factors are considered, preoperative measures should be taken, such as administration of calcium, vitamin K, hemostatic drugs and coagulation factors that the body lacks, or transfusion of fresh blood. The formation of hematoma or seroma isolates the skin slice from the trauma of the recipient area and prevents the normal progress of the skin slice viability process. If the area does not exceed 1cm×1cm, the skin piece can still be viable due to the “crossing phenomenon”; otherwise, the local skin piece will eventually become necrotic. If the hematoma or seroma can be detected and excluded in time, it can still be saved from failure. If the seroma lasts for a long time, but the skin piece is not necrotic, its bottom surface may be epithelialized from the epithelial tissue attached to the skin, and the fluid is removed through a small incision, and the bottom layer of the skin piece is gently scraped to remove the new epithelium, and then pressure is applied to bandage it, and it is still eager to survive. For this reason, the surgeon is required to be patient and do a good job of wound hemostasis, and only if the hematoma or blood clot is excluded can the transplanted skin piece be expected to survive. 2.Improper dressing and fixation After transplantation, the skin piece must maintain a stable and close contact with the wound surface of the recipient area in order to survive, if the fixation is poor and the exchange is misaligned, the circulation cannot be established or is destroyed just after establishment. Therefore, proper dressing and braking after implantation are very important. Medium-thickness, full-thickness, and subdermal vascular network skin pieces should be sutured and fixed after transplantation. It should be fixed with a “package pile”. Especially for the dorsal side of the hand, foot, and lower forearm, the implant bed is uneven, so in order to make the skin pieces adhere closely to the wound surface, using soft scrap gauze or gauze as the “package pile” is the ideal material to solve the problem of skin piece and bed adhesion. When the contact between the “packet pile” and the skin piece becomes hard due to the drying of the oozing blood after the operation, it has lost its soft and even effect on the skin piece compression, but has a hard pressure on the skin piece, then the “packet pile” should be removed in time, and the shaken gauze should be used instead. placed on the surface of the skin piece, and then dressing, bandage bandage. This bandage is called soft bandage, continue to play the role of “package pile”. Proper dressing fixation with proper tension is conducive to the capillary connection between the wound and the skin fragment. The implant area is generally wrapped with a pressure of about 20-25 mmHg. However, excessive compression is not conducive to capillary growth, such as in the occipital area, frontal area and front of the tibia, which can cause necrosis of the skin fragments that have begun to establish blood flow by compression. The area around the bony prominence should be padded with loose gauze, and the pressure of the bandage should be evenly distributed but not tight. The neck, hip, perineum and extremity implants should be splinted for joint fixation. To avoid dislocation of skin pieces. Wrapping the implant area with elastic bandage can achieve the effect of compression and restriction of activities. In addition, after the implantation of the face and neck, the whole liquid food or nasal feeding for 3~5 days and less talking are also used to reduce the movement and help the vascular reconstruction of the skin piece. 3.Infection Traumatic septic infection is also a common cause of implant failure. Therefore, aseptic operation must be strictly observed. Emergency wound debridement has become the top priority for infection prevention, including the removal of various kinds of dirt and foreign bodies, and the removal of inactivated tissues. Fresh wound implants have less chance of infection. In the case of granulation wound implantation, attention should be paid to every aspect, such as wet dressing, cleaning, drainage, proper application of antibacterial drugs, complete hemostasis during surgery and transplantation of thin skin pieces, etc. It should also be noted that the skin pieces should not be under excessive tension. Postoperative measures should also be taken to prevent infection, and prompt attention should be paid to reveal the wound if there are any signs of infection. Dressings should be changed in advance, and if infection is found to be septic, it should be drained promptly to avoid full failure due to extension of infection. Most skin patch infections do not occur within 24 hours postoperatively. Low fever, increased local odor and pain, and periwound erythema are signs of infection. In case of traumatic streptococcal infection, especially Streptococcus b haemolyticus, fibrinolytic enzymes can be produced to dissolve the fibrous adhesions between the skin slice and the skin-receiving wound and separate them from each other. Staphylococcal infections can cause skin fragments to lyse, or the wound surface can become septic and form abscesses, causing the skin fragments to float. These are serious obstacles to the survival of skin fragments, while Pseudomonas aeruginosa has less impact on the survival of skin fragments. It is important to pay attention to local treatment, such as removal of necrotic tissue, wet dressing with antibiotics to enhance drainage, etc. After infection occurs, we cannot simply hope for systemic antibiotics. Supplementary implantation should be carried out as early as possible after the infection is controlled and the wound surface is closed. 4.Improper selection of indications and transplantation methods The survival of skin slice transplantation depends entirely on the good vascular bed of the recipient skin wound. If the recipient skin wound is poor in blood flow, or there is a bloodless area larger than 1cm×1cm, and it cannot be covered by the tipped transfer of adjacent soft tissue, it is not an indication for skin slice transplantation. Forced suturing will lead to failure. Skin grafting on granulation wounds should be performed after the infection is controlled and the granulation tissue that meets the conditions for implantation is cultivated to ensure the survival of the skin piece. If the granulation condition is still poor, the infection is also serious, and the secretion is more, but the condition requires urgent skin implantation, a thinner stamp-like or mesh-like skin implant should be used in general. If a large thicker skin graft is used, it is easy to cause partial or total inactivation due to poor drainage of pus under the skin sheet. If the area of skin grafting on exposed bone cortex or tendon exceeds 1 cm in diameter, it may affect the survival of the skin slice, and local skin flap or tissue flap can be transferred to cover the exposed tendon and bone before skin grafting. Even if the periosteum is intact and the deep tissue of the tendon lining is exposed, although it can be viable, the wound will still need to be repaired with a second-stage flap after healing because it is easy to produce pain and tendon adhesions. For palmar tendon membrane and metatarsal fascia exposed trauma, it is better to remove palmar tendon membrane and metatarsal fascia and then make free skin flap graft. For lower limb varicose vein calf ulcers, chronic ulcers in the middle of extensive scarring, longer decubitus ulcers, or ulcers and decubitus ulcers after nerve paralysis, etc., local scarring, poor blood supply, the presence of infection or loss of neurotrophic parts, free skin flaps are difficult to grow and should be given full attention. 5, systemic reasons anemia, hypoproteinemia, chronic failure, malnutrition, etc. are not conducive to the survival of skin fragments. In case of burn sepsis, the skin graft may fail. Diabetic patients should first control their blood sugar before skin grafting can be successful. Therefore, the overall comprehensive examination before skin grafting surgery should not be neglected. 6.Donor area treatment The main principle is to prevent infection and avoid mechanical damage. The postoperative care of the donor area is very important after the removal of the thick, medium-thick or full-thick skin slice. Improper treatment can cause infection, delayed healing and scar growth in the donor area, bringing new pain to the patient and increasing the patient’s hospitalization cost. After the skin slice is cut from the donor area, firstly, avoid unnecessary wiping and hemostasis of the donor area, and secondly, often cover with meticulous petroleum jelly gauze or ulcer oil thickening and 12-14 layers of implant gauze, exceeding the wound edge by 3-5 cm, and then wrap it with bandages under pressure to prevent its movement. If the skin donor area is in the thigh or lower abdomen, rest in bed for 10-14 days, with the knee joint padded and in a slightly flexed position. The dressing should also be checked for loosening, displacement, oozing or infection at any time. The first dressing change time for the skin donor area is usually 5 to 7 days. When changing dressings in the skin supply area, the inner layer of petroleum jelly or ulcer oil is thickly retained, and if the inner layer is removed prematurely, the new epithelium will be torn, causing pain and bleeding. When operating, remove the outer wet dressing, replace it with a new sterile dressing and continue to apply pressure to the dressing. In case of infection, the inner wet dressing can be cut, cleaned, and wet or semi-exposed. The donor area can be greased after healing to prevent the new epithelium from drying out and thus splitting. The thick cut skin donor area should also be wrapped with an elastic bandage for more than 3 to 6 months to prevent scar growth or other changes. The donor area after excision of full-thickness skin and skin containing subdermal vascular network is usually closed by suturing. The donor area after excision of the dissected skin slice is proliferated by the residual epithelial cells and appendages that migrate and fuse with each other on the wound surface. Generally, the donor area heals within 10 days for thick-edged skin pieces and within 14-21 days for medium-thick skin pieces. The donor area after skin removal is a sterile wound and is mostly bandaged with sterile gauze under pressure. It was found that the donor area heals slower with exposure therapy, how to bake dry the donor area with light bulb or hot blowing air will slow down the epithelial growth and dryness, making the patient feel discomfort and pain, keeping the donor area wound moist can make the donor area heal faster. Most of the delayed healing in the donor area is due to infection or over-thickness of the skin slice, and if there is no hope of self-healing after treatment, the skin can be implanted with a thick skin slice. After healing, the recipient area and the donor area need to be bandaged elastically to avoid mechanical injury and to reduce local scar proliferation reaction.