The presence of “gas” in the drainage tube after breast surgery is usually nothing to worry about and does not flow into the body. Drainage tubes are usually placed under the skin after breast surgery to drain blood and tissue fluid from the wound. Since the drain is buried under the skin, it is not directly connected to the pleural cavity or blood vessels. In addition, what appears to be “gas” in the drain tube is actually a vacuum caused by the absence of blood or fluid from the wound, or less exudation, and the absence of fluid in the tube, and is not really gas. Therefore, there is no need to worry about “gas” entering the body for patients who have indwelling drains after breast surgery. After breast surgery, patients should pay attention to the local care, do not move too early which may lead to wound dehiscence and dislodgement of the drain. If any abnormality occurs during the period of indwelling drainage tube, consult your doctor in time and do not do anything on your own to avoid serious consequences.