I. Vesicoureteral reflux The anti-reflux mechanism of the vesicoureter is released after the stent tube is placed, and long-term retention may cause passive dilatation of the end of the ureter. Under the effect of pressure difference in the vesicoureter, urine in the bladder may reflux to the upper urinary tract along the stent tube. This can cause pain and discomfort in the lower back and abdomen, pyelonephritis, and in the long term, impaired kidney function. Increase the frequency of urination and empty the bladder in a timely manner. Slowly increase the bladder pressure and avoid sudden increases in bladder pressure caused by forceful coughing and defecation as well as abdominal pressure urination. Routinely leave the catheter in place for 3~5 days after surgery to reduce the intra-vesical pressure. Ureteral stent tube syndrome Ureteral stent tube syndrome, also known as ureteral stent tube related symptoms, includes urinary frequency, urinary urgency, dyspareunia, hematuria, suprapubic pain and low back pain, and its incidence is more than 80%. α-blocker tamsulosin has been shown to significantly improve lower urinary tract symptoms and improve quality of life. When a patient develops ureteral stent tube syndrome with unsatisfactory results by conservative treatment, the stent tube needs to be removed promptly. Infection is a common complication, and the incidence of infection was 7.1%, 23.6% and 47.1% for stent tubes left in place for 20 d-30 d, 30 d-90 d and >90 d, respectively. Quinolones and aminoglycosides can be absorbed by biofilm and can play a role in preventing and controlling infections. The fundamental solution is to shorten the retention time of the stent tube, remove it as early as possible or replace it at the right time. Fourth, peritubular scaling Scaling and bacterial infection are mutually reinforcing. Among them, the retention time is the most important, and the scaling rates of <6 w, 6 w-12 w and >12 w are 9.2%, 47.5% and 76.3%, respectively. V. Displacement Displacement was divided into upward and downward displacement, with an overall incidence of 1.7% to 9.5% and an incidence of 2% for upward displacement. Inadequate relief of obstruction or re-infarction For extraluminal tumor compression obstruction, such as retroperitoneal tumor and pelvic tumor, the success rate of the first cannulation is 72%-92%, and the failure rate of distant drainage can be 16%-53%. The main reasons for failure may be severe encapsulation around the stent tube, filling of the lateral holes with ureteral mucosa, and blockage of the lumen by necrotic tissue and blood clots. Radiotherapy can cause local ischemia of the ureter and promote erosion. The proximity of pulsating arterial blood walls, arterial patches, and pseudoaneurysms to ureters with long-term indwelling stent tubes is a condition for the formation of ureteroarterial fistulas.