How is the severity of hydronephrosis classified? The severity of hydronephrosis can be classified into 3 levels: mild, moderate and severe. From the perspective of pathological anatomy, mild hydronephrosis means only the pelvis is hydronephrosis, moderate is hydronephrosis in both pelvis and calyces, and severe hydronephrosis is when the whole kidney is filled with urine and has lost its normal shape. Clinically, ultrasound examination is commonly used to determine: if the renal pelvis is dilated (expressed by the value of sinus separation on the examination report) more than 1 cm but less than 3 cm, the kidney size and shape are not obviously abnormal, and the thickness and echogenicity of the renal parenchyma are normal, it is mild hydronephrosis; if the renal pelvis is dilated by 3-100 px, the renal calyces are also obviously dilated, the kidney volume is mildly enlarged, the shape is full, the parenchyma is mildly thinned, and the renal column is not clear, it is moderate hydronephrosis. If the renal pelvis is dilated >100px, the kidney is large, the morphology is abnormal, the parenchyma is significantly thinner or cannot be displayed, and the whole kidney area is liquid dark area, it is severe hydronephrosis. If only a single calyx is hydronephrosis and the renal pelvis is normal (as caused by a calyx stone), it is usually classified as mild as well. How to treat hydronephrosis caused by kidney stones? From a professional point of view, hydronephrosis is not a disease, but a pathological change after the obstruction of the urinary tract, so the key to treat hydronephrosis is to release the obstruction of the urinary tract. For hydronephrosis caused by kidney stones, as long as the stones are cured, the hydronephrosis will be reduced or eliminated naturally. Depending on the size, location and time of obstruction of stones, different methods such as drugs, extracorporeal lithotripsy and surgery can be used to remove the stones. Sometimes, in urgent cases, such as acute urinary tract infection or renal insufficiency, in order to relieve the condition as soon as possible, the hydronephrosis can be treated first and the urine can be drained, while the stone can be left to be treated after the condition improves. The treatment methods are percutaneous renal puncture and drainage and transurethral ureteral built-in tube drainage. Can kidney function be restored after hydrocele is eliminated? Why? After the formation of hydronephrosis, the kidney function on the affected side is inevitably affected, and the degree of the effect depends on the obstruction site, the degree of obstruction, the duration and other factors. After the obstruction is removed, the hydronephrosis can be reduced or disappeared and the kidney function can be restored, but the amount of restoration depends on the time of obstruction, age and other factors. If the obstruction is incomplete, that is, partial obstruction, urine passage but not smooth, or just individual calyces fluid accumulation, then the impact on renal function is smaller, and renal function will recover faster after fluid elimination. On the contrary, if the obstruction is complete, it will have a greater impact on renal function. Studies have shown that after a few weeks of complete obstruction, irreversible damage to the kidney will occur, and even if the obstruction is lifted, the kidney function cannot be completely restored to normal. Therefore, once hydronephrosis occurs, the obstruction should be removed as soon as possible. In addition, the recovery of renal function is also related to the age of the patient, the younger the age, the easier the recovery of renal function.