Any part of the urinary system is completely or partially obstructed, acutely or chronically, due to intraluminal or extraluminal causes. If the obstruction is not removed in time, it will eventually lead to hydronephrosis and impair renal function. In the upper urinary tract, where the pelvis and ureter are obstructed, hydronephrosis develops quickly, but often one side is damaged; in the lower urinary tract, where the bladder and urethra are obstructed, the kidney damage develops slowly at first because the bladder is used as a buffer, but often the kidneys are damaged bilaterally. What are the examination methods of urinary tract obstruction? 1, urine examination In case of co-infection, there can be white blood cells and pus cells in the urine. There is non-specific bacterial growth in the urine culture. In case of coexisting stones, there are red blood cells in the urine. 2.Cystoscopy In case of lower urinary tract obstruction, cystoscopy can reveal prostatic hyperplasia, bladder neck contracture, bladder stones and lesions such as trabeculae, small rooms and diverticulae in the bladder. 3.Urography In case of coexisting stones, the plain film may show opaque stone shadows. In case of upper urinary tract obstruction, there is often hydronephrosis on the affected side. Severe hydronephrosis often leads to renal function deficit and does not appear. Ureteral hydrocele may show enlargement and tortuosity. In the case of lower urinary tract obstruction, the bladder rotunda is irregular and the size and location of the diverticulum can be shown when there is a diverticulum. Cystourethrography can show lesions such as urethral strictures and valves. 4.B-type ultrasonography When the upper urinary tract obstruction, the affected kidney can often be detected in the liquid flat segment, suggesting hydronephrosis. In case of coexisting stones, stones and their acoustic shadow can be detected. In the case of lower urinary tract obstruction, residual urine of different degrees can be measured in the bladder. CT scan can also detect stones and sometimes tumors of the renal pelvis and ureter. 6.Renal function test In the early stage of obstruction, renal function often does not change. Unilateral upper urinary tract obstruction often leads to decreased renal function on the affected side, which can be suggested by indocyanin test, isotope renogram and intravenous urography. Long-term bilateral upper urinary tract obstruction and lower urinary tract obstruction may lead to renal insufficiency on both sides, with elevated urea nitrogen and creatinine. Isotope nephrogram can show impaired kidney function or obstructive nephrogram. 7.Urodynamic examination In the case of lower urinary tract obstruction, the maximum urinary flow rate is reduced (<10ml/sec) and the intra-vesical pressure is significantly increased during voiding (>70cm water column). Urological X-ray and ultrasound scan have the potential to detect the cause and the degree and location of obstruction. CT and MRI are performed if necessary. Treatment needs to be considered in the context of the etiology and the general condition of the patient. Functional obstruction in pediatric patients can be observed and waited for. The cause should be removed to keep the urinary tract open. If the cause cannot be removed, a fistula above the obstruction can be performed in case of emergency to drain the urine to reduce the damage to the kidney. The clinical manifestation of upper urinary tract obstruction is back pain on the affected side. If the hydronephrosis is obvious, a mass may be palpable in the upper abdomen. If the obstruction is intermittent, the mass may be large or small. In case of co-infection, there may be fever, pyuria and some symptoms such as frequent and urgent urination. Hematuria may occur when stones are present. Bilateral severe hydronephrosis can lead to chronic renal insufficiency, such as loss of appetite, nausea, vomiting and anemia. Anuria may occur in the case of bilateral upper urinary tract obstruction.