What symptoms appear in hydronephrosis are related to the degree of hydronephrosis and the time of hydronephrosis formation: 1. Acute obstruction caused by hydronephrosis is often accompanied by significant back pain. The sharp increase in pressure in the renal pelvis due to hydronephrosis can cause strong stimulation of pain receptors on the renal envelope, which can produce severe pain. The most common clinical condition is kidney stones or ureteral stones, which can produce severe pain after causing hydronephrosis, called renal colic; 2. Chronic hydronephrosis causes lumbago or lumbar distension. In the early stage, a small amount of hydrocele can have no conscious symptoms, and with the gradual increase of the amount of hydrocele, it can lead to lumbar distress and lumbar distension, but often there is no obvious severe pain; 3. The more severe the degree of hydrocele, the greater the possibility of the above symptoms. A small amount of hydrocele will not produce any conscious symptoms, and patients are often found during an occasional physical examination. If there is prolonged lumbar distress and swelling, it is often accompanied by more than moderate hydronephrosis.