If the foreign body is swallowed by mistake by some small babies, and these foreign bodies are relatively small and round, and do not release some harmful and irritating substances, they usually do not show special symptoms. However, if it is a button battery that releases toxic or irritating substances, it is very dangerous and can cause intestinal perforation and life-threatening infectious shock. The symptoms of abdominal pain are generally not expressed by small infants, usually with a curled abdomen and irritable state. If an infant is seen to have a curled abdomen, afraid to straighten its waist, and if its abdomen is pressed, it can also appear to be crying and restless, which may be a manifestation of abdominal pain. There will also be diarrhea, nausea and vomiting, which are all signs of irritants and toxic substances stimulating the gastrointestinal tract. If the foreign body is relatively sharp, it may damage the mucosa and blood vessels of the esophagus, and there will be vomiting of blood, tarry black stools, or even blood in the stool.