RESUMEN
This study was done to determine the effect of stenting on the histology of the ureter and the reversibility of these changes and to assess the importance of stenting on ureteral healing after different surgical procedures, with clinical evaluation of the use of short stents to replace the traditional long ones, especially because most reports concerned with ureteral healing and the stent dated back to the late fifties, with controversial results with some later reports. The experimental part included 12 dogs, in which a segment of the ureter 2 cm long and including two thirds of the circumference of the ureter was excised, the ureter was stented across the site of the defect using long stents, i.e. from the kidney to the bladder in six cases, in the other six cases short stents were applied just enough to bridge the ureteral defect. Intravenous urography was done for follow up of the dogs after removal of the stents to evaluate the state of the involved renal unit, while histopathological examination of the healed segment, the ureter above and below the healed segment was done after sacrificing of the dogs. It was concluded that proper ureteral healing after excision of part of the ureteral wall can occur around a stent whether it is short or long and that the use of short stent avoids the harmful effect of the stent on the whole ureter. Application of short stents in the human ureter was extremely beneficial and prevents the possibility of stent migration and avoid the necessity of endoscopic extraction of the stent when it is only required to divert urine for short time