If you have a pain in your belly when you urinate, it is recommended to go to the hospital for examination, the possible causes are as follows: 1, cystitis, when inflammation occurs, the bladder mucosa is congested and edematous with inflammatory erosion reaction, so that when urinating or holding urine, there can be pain in the small abdomen, can be accompanied by urinary frequency, urinary urgency, serious patients may be accompanied by urinary bleeding phenomenon, need to go to the hospital for urine laboratory tests to further confirm the diagnosis. 2, bladder stones, in the process of stone flow with urine, can cause local irritation and small abdominal pain, some patients can be accompanied by interruption of urination, urinary frequency, urinary urgency and other symptoms. A small number of patients may have hematuria, which requires further ultrasound examination of the urinary tract to confirm the diagnosis. 3. Tumors of the urinary tract, often seen in elderly patients, may have symptoms of hematuria if there is a tumor in the early stage, and later may have pain in the small abdomen when urinating, which requires further ultrasound, CT, or cystoscopy of the urinary tract to further rule out.