The distension of the right side of the belly is caused by the following conditions: First, patients with gastroenteritis may have diarrhea, accompanied by nausea and vomiting, and in severe cases, edema of the intestinal canal, which may manifest as pelvic effusion. The patient will also show lower abdominal distension and pain with fever, laboratory tests have increased blood count and other abnormal performance, timely anti-infection treatment, intravenous fluid supplementation, the patient’s symptoms can gradually improve. Second, the common appendicitis, because the appendix is located in the right lower abdominal iliac fossa, so the typical symptoms are pain in the right lower abdomen, accompanied by fever, and in serious cases, there will be obvious rectal irritation symptoms, especially septic appendicitis. For appendicitis, early diagnosis should be promptly treated by surgery, which is usually performed under epidural anesthesia to remove the appendix, and postoperative anti-infection treatment is also required.