Heparin is usually injected subcutaneously and does not enter the abdominal cavity, so it does not injure the intestine. If the pain is in the stomach, it is recommended to actively look for the cause, which is not necessarily related to the heparin injection. If the skin at the local injection site of the stomach is painful, and there is local bruising, it may be due to local bleeding after the heparin injection without good pressure, which can be slowly absorbed and recovered. In addition, the main side effect of subcutaneous injection of low molecular heparin is bleeding, and there is no side effect of abdominal pain.