When a stone gets stuck in the middle segment of the ureter, it can block the urinary tract. This prevents the urine in the kidney from flowing smoothly through the ureter into the bladder, leading to hydronephrosis (kidney swelling due to urine accumulation).In general, for stones in the middle segment of the ureter, it's difficult to locate them using B - ultrasound during extracorporeal shock wave lithotripsy. This is because during a B - ultrasound examination, the presence of gas in the intestines often interferes, making it hard to visualize the stones in the middle segment of the ureter.Therefore, in this situation, treatment can only be achieved through minimally invasive surgery. Patients can visit the Department of Urology at their local hospital to undergo transurethral ureteroscopic holmium laser lithotripsy.During the procedure, a ureteroscope is inserted through the patient's urethra and advanced to the middle segment of the ureter. Once the stone is located, a holmium laser fiber is used to break it into smaller pieces, which can then be excreted from the body.