Many patients have to have their spleen removed because of cirrhosis, hypersplenism or hematologic disorders. After spleen removal, postoperative splenic fever often occurs, and the patient’s fever lasts longer than the usual response time after major surgery, lasting 1 to 2 weeks, or even more than a month or longer, often referred to as “post-splenectomy fever”. This often delays the patient’s recovery, prolongs the patient’s hospital stay, and increases the patient’s costs. This is a serious concern for splenectomy patients and clinicians. So, what is splenic fever all about? (1) Hematoma formed by bleeding in the splenic fossa; (2) Infection under the diaphragm or in the abdominal cavity; (3) Reactive fluid or infection formation in the left side of the thoracic cavity above the diaphragm or pleurisy, especially in splenectomy with a combined thoracoabdominal incision; (4) Splenic vein thrombophlebitis; (5) Pancreatic tail injury; (6) Infection in any part of the body due to decreased immunity of the body after splenectomy; (7) Sepsis. Diagnosis: (1) Ultrasound or CT to rule out subdiaphragmatic fluid or infection, pneumonia, pulmonary atelectasis, pleural effusion, portal vein thrombosis. (2) Routine blood count: white blood cells and neutrophils are normal or slightly high, with no leftward nuclear shift of neutrophils. (3) The use of non-steroidal antipyretic and analgesic drugs is effective, such as anti-inflammatory pain. Some pyrogenic substances, especially endogenous pyrogens (mainly endogenous pyrogens produced by lymphokines stimulating large monocytes), cannot be inactivated and excluded effectively and completely, which can act on the thermoregulatory center and make the temperature adjustment point rise. In addition, the formation of specific antibodies and immunoglobulins is reduced after splenectomy, and the production and action of modulators are affected, resulting in fever. It can be seen that splenic fever has the following characteristics: i. persistent and fluctuating ii. exclusionary: various infectious factors are excluded. iii. Self-healing: often resolves on its own, independent of the application of antibiotics. The cause is often unclear and is often associated with splenic fossa exudation, absorption fever, splenic vein thrombosis, immune deficiency, and abnormal liver function.