Elderly people’s stomach suddenly hard and bulging is usually digestive diseases, peritonitis, peritoneal fluid, prostate hyperplasia caused by urinary retention and so on. 1. Digestive tract diseases: for example, acute intestinal obstruction, intestinal perforation, acute gastritis, intestinal flatulence, constipation, indigestion and other causes, can lead to the elderly stomach suddenly hard and bulging, need to do timely abdominal examination, stool examination. 2. Peritoneal diseases: for example, acute peritonitis, peritoneal fluid, etc., can cause the stomach of the elderly suddenly hard and bulging. 3. Urinary retention: urinary retention caused by prostate hyperplasia can cause a hard and bulging stomach, the location of the hard and bulging stomach is usually in the lower abdomen, if it is urinary retention is usually relieved by catheterization. Elderly people who have a sudden hard and bulging stomach need to consult a doctor in time to avoid delaying their condition.