Normal negative pressure gastric drainage fluid can be the color of gastric contents, and when there are no gastric contents, it is transparent and colorless gastric juice; when bleeding, gallstones and other diseases occur, the color of drainage fluid will be abnormal. The drainage of negative pressure gastric drainage is gastric contents, mainly food residue; after the food is removed from the stomach, the drainage fluid is mainly gastric juice, which consists of hydrochloric acid, pepsin, and other substances, which are usually transparent, colorless, and tasteless. In the event of digestive disease, the color of the drainage fluid may change. When bile reflux occurs, the gastric drainage fluid may be dark green or grass green; when gastric bleeding occurs, the gastric drainage fluid may be coffee-colored, or red when the bleeding is rapid. It is recommended to inform your physician if the color of the gastric drainage fluid is abnormal.