Stones in the upper left ureter may be secondary to kidney stones, may be primary stones, and may also be caused by ureteral stenosis or cysts, medical factors. 1. Kidney stone: it may be related to metabolic abnormalities in the body and dietary factors. When kidney stone exists in the kidney, it may move downward and will get stuck in the upper ureter, and then the stone will exist in the upper ureter. 2. Ureteral stenosis or cysts: when the left side of the upper ureter is narrowed or cysts, the passage of urine will be impeded or the flow will be slow, resulting in crystallization of urine, which will be easy to form stones over time. 3. Medical factors: For example, if you have surgery on the upper ureter and use non-absorbable sutures during the surgery, you may form stones after the surgery. 4. Primary stones: Some metabolic abnormalities can lead to the development of stones in the body. After the symptoms of stones in the upper left ureter, it is recommended to consult a doctor for appropriate examination and treatment to avoid serious complications.