1ml low molecular weight heparin is equivalent to 9500IU anticoagulant factor Xa. In prevention and treatment, low molecular weight heparin should be administered by subcutaneous injection. In hemodialysis, it is administered by intravenous injection. Can not be used for intramuscular injection. When subcutaneous injection is performed subcutaneously, the patient is prone to lie down, and the injection site is in the subcutaneous tissue of the anterolateral or posterolateral abdominal wall, alternating left and right. The injection needle should be inserted vertically and completely into the skin fold picked up by the injector's thumb and forefinger, rather than horizontally. During the whole injection process, skin wrinkles should be maintained. Preventive treatment The following recommendations are generally applicable to all patients undergoing surgery under general anesthesia. Patients undergoing surgery under epidural anesthesia may theoretically increase the possibility of epidural hematoma formation, so whether to inject before operation should be considered as appropriate. Frequency of use: once a day. Surgery with moderate risk of thromboembolism. For surgery with moderate risk of thromboembolism, and the patient does not show serious risk of thromboembolism, injection of 2850IU(0.3ml) a day can effectively play a preventive role. The first injection was made about 2 hours before operation. Surgery with high risk of thromboembolism: the dosage used in hip and knee surgery should be adjusted according to the patient's weight. The daily injection dose is: 38IU/kg-before operation, for example, before operation 12 hours-after operation, for example, after operation 12 hours-and then used daily until the third day after operation, and the dose is adjusted to 57IU/kg from the fourth day after operation. Dose can be determined according to the patient's weight range from the following table. Other conditions: For some operations (especially tumors) and/or patients (especially patients with a history of thromboembolism) with high risk of thromboembolism, 2850IU(0.3ml) of low molecular weight heparin is enough.