Pyelonephrosis is an enlargement of the renal pelvis and calyces accompanied by atrophy of the renal tissue due to urinary tract obstruction. Urinary tract obstruction can occur anywhere in the urinary tract, either unilaterally or bilaterally. The degree of obstruction can be complete or incomplete and can cause hydronephrosis after a certain period of time. The narrowing or obstruction of the ducts in any part of the urinary tract and the normal dysfunction of the neuromuscles can cause obstruction to the passage of urine, resulting in urinary flow obstruction. The pressure in the part above the obstruction gradually increases due to poor urine discharge, and the lumen expands, eventually leading to hydronephrosis, dilatation, thinning of the renal parenchyma, and decreased renal function, and serious consequences of uremia if bilateral obstruction occurs. (I) Routine blood tests In the case of secondary infection, the total blood leukocyte count and neutrophils increase. (ii) Urine examination Red and white blood cells and pus cells can be detected in the urine plating. Urine culture is positive. （Ultrasound is the preferred method to differentiate from renal cysts and renal parenchymal tumors, and is useful for understanding the urinary tract. (4) X-ray examination 1.Dry abdominal film can be seen in different degrees of kidney shadow enlargement, and at the same time can understand whether there are stones or kidney calcification. 2.IVU can understand the function of the hydronephrosis kidney and the contralateral kidney, if the kidney is functional, the dilatation of the renal pelvis and calyces on that side can be observed. If the image is not clear, high-dose delayed excretion urography is feasible. 3, pyelogram Under aseptic operation and infection prevention measures, retrograde pyelogram is performed to clarify the cause and site of obstruction and hydronephrosis. (v) Other Such as CT periprocedural tired kidney map, renal scan, ECT, etc., have the site of obstruction, the size of the kidney, and the amount of renal function can provide important clues. (vi) Symptomatic examination Patients are often asymptomatic for a long period of time until they develop abdominal masses and a feeling of distension in the lower back before being noticed. The masses are mostly found unintentionally and are usually cystic in nature. Pain is usually mild or even completely painless. However, in cases of intermittent hydronephrosis (caused by ectopic vascular compression or renal prolapse), renal colic may occur, with severe pain radiating along the rib cage and ureteral pathways. It is mostly accompanied by nausea, vomiting, abdominal distension and scanty urination. The pain is usually relieved within a short time or a few hours, followed by the discharge of a large amount of urine. On examination, an enlarged kidney may be palpated. In the case of massive hydronephrosis, the tension may not be very high. If the hydronephrosis is complicated by infection, there is purulent urine and systemic toxic symptoms, such as chills, fever, headache and gastrointestinal disorders. Some patients have urinary tract infection as the initial symptom. Any patient who has poor treatment effect on urinary tract infection must pay attention to the presence of obstructive factors. In severe obstruction, inflammatory exudate cannot be excreted through the urine, and there are no white blood cells in the urine, but local pain and pressure are more pronounced in such cases. Distended hydronephrosis is more susceptible to trauma and may rupture and bleed with minor injury. The flow of urine into the retroperitoneal space or peritoneal cavity causes severe reactions, including pain, tenderness, and systemic symptoms.