A small amount of pleural effusion after gastric cancer surgery usually doesn’t need to be treated and continue to be observed; however, a large amount of pleural effusion needs to be punctured and drained. Gastric cancer surgery will stimulate the diaphragm, and even the larger scope of surgery will spread to the chest cavity, so some patients will have pleural effusion. A small amount of pleural effusion will not have obvious effect on patients, and it will be gradually absorbed after a period of time, so it does not need special treatment, and it needs to continue observation. If there is more fluid, obvious compression symptoms, or the fluid is combined with infection, patients should consult doctor for timely drainage and anti-infection treatment. Therefore, pleural effusion after gastric cancer surgery is relatively common and most of them do not need treatment, while special cases need puncture and drainage.