Pain and bloating in the middle of the abdomen is considered to be caused by acute gastroenteritis, but may also be caused by malignant tumors, urinary tract infections, urinary retention and other diseases. 1. Acute gastroenteritis: acute inflammation of gastrointestinal mucosa caused by unclean diet, mainly manifested as abdominal pain, diarrhea, vomiting and other symptoms. 2. Malignant tumor: when colon cancer grows and oppresses or invades surrounding tissues and metastasis occurs, abdominal pain and distension in the middle of abdomen can appear, and the location of pain is determined by the site of tumor growth. Bladder cancer can also present abdominal pain, abdominal distension and other symptoms. Most patients can have painless hematuria, frequent urination, urgency, pain in urination, difficulty in urination and other symptoms. 3. Urinary system infection: such as urethritis, cystitis, etc., which is mostly caused by bacteria and other retrograde infections. Patients may experience abdominal distension or tingling, often accompanied by bladder irritation symptoms such as frequent urination, urinary urgency, urinary pain, and even fever, hematuria and so on. 4. Urinary retention: mostly caused by mechanical obstruction such as urinary stones and power obstruction such as bladder nerve injury, may appear difficulty in urination, lower abdominal pain and discomfort, abdominal distension, urinary incontinence and other symptoms. It is recommended to consult a doctor in time to clarify the diagnosis and carry out targeted treatment.