Right upper quadrant pain can originate from the liver, cholecystic duct, gallbladder, pancreas, or surrounding organs. Peritonitis in the right upper quadrant of the abdomen can be caused by lesions in these organs as well as the adjacent organs, such as the kidney and colon. The kidneys are surrounded by Gerota's fascia and fat; therefore, mild local inflammation may not cause peritonitis. Herein, we report the case of a 72-year-old woman with right-sided abdominal pain who was diagnosed with urinary extravasation due to a ureteral stone. Urinary extravasations can present with peritonitis. For effective diagnosis, prompt physical examination and abdominal ultrasound are essential, with the extent of extravasation being key to effective management. Therefore, general physicians should consider urinary extravasation, which is typically caused by kidney and urinary stones, in patients with right upper quadrant pain.