The pain in the abdomen after urination, then the possible causes: 1, acute and chronic cystitis, when the bladder inflammation, bacterial invasion of the bladder mucosa epithelium and lead to mucosal congestion, edema, and the appearance of mucosal erosion. The normal bladder mucosa has a layer of aminosaccharide on its surface, which is used to block urine from coming into direct contact with the bladder mucosa. When infection occurs, the amino sugar layer is destroyed and urine comes into direct contact with the bladder mucosa and submucosa, causing pain in the bladder area, i.e. pain in the small abdomen. 2. Bladder stones, patients with stones can have microdamage to the mucosa due to stone irritation, and pain can occur when urine comes into contact with the damaged area. During urination, the stones float with the urine, which aggravates the irritation factor, so the pain in the small abdomen will increase after urination. The stone may also obstruct the urethra and cause sudden interruption of urination. Further ultrasound examination is needed to confirm the diagnosis.