0.4 is considered to be 0.4 cm. It is possible that a 0.4cm polyp found during gastroscopy that was not removed is not serious or has other contraindications. 1. not serious: gastric polyps are benign lesions on the surface of the gastric mucosa, which may be associated with Helicobacter pylori infection, medication, heredity, the environment, etc. 0.4cm gastric polyps are relatively small, and generally do not cause symptoms or lead to cancer, so it is possible that gastroscopy found that 0.4cm polyps have not been removed. 2. There are other contraindications: when the body has coagulation disorders, platelet lowering and other diseases, gastroscopic removal of polyps may lead to unstoppable bleeding, so gastroscopy found that 0.4cm polyps may not be removed. If there is a gastroscopy found 0.4cm polyp did not remove the situation, but also need to be based on the blood routine, coagulation function and other items of the results of judgment, you can also consult with the attending physician for reasons.