Analysis Of Related Factors Of Ureteral Stricture After Holmium Laser Lithotripsy

Objective: Analyze the related factors of ureteral stricture after ureterolithiasis treated by intracavity holmium laser lithotripsy,to provide reference for prevention or reduction of ureteral stricture after holmium laser lithotripsy.Methods: To collect the clinical indicators of ureteroscopic holmium laser lithotripsy(URHL)and percutaneous nephrolithotripsy with holmium laser(PCNL)performed by the same specialist in our department from January 2018 to December 2019.A total of 123 patients with ureteral stricture were excluded.there were 106 cases in URHL group and 17 cases in PCNL group.The patients were followed up for 1-2 months by color Doppler ultrasound and computed tomography(CT)to monitor the hydronephrosis.The complication of ureteral stricture after holmium laser lithotripsy is defined as follows: during the follow-up period,the hydronephrosis increased progressively,and finally diagnosed by ureteroscopy for ureteral stricture or atresia.The risk factors of ureteral stricture after holmium laser lithotripsy were found by statistical method.To compare the characteristics of the corresponding cases with holmium laser lithotripsy after percutaneous nephrolithotomy,and analyze the deep seated factors of ureteral stricture after holmium laser lithotripsy.In the further analysis,we randomly monitored the data related to the temperature change during the operation of 15 cases of ureteral calculi treated by intracavitary holmium laser lithotripsy in the past year,including 13 cases of urhl13 and 2 cases of PCNL.The influence of two kinds of holmium laser lithotripsy on ureteral temperature during operation was recorded and analyzed,and the correlation between temperature factors and ureteral stricture after holmium laser lithotripsy was discussed.Results: In the URHL group 6 cases developed into ureteral strictures,stenosis rate(5.7%,6/106),and PCNL group had no ureteral stricture after operation(0%,0/17).Ureteral stricture and perforation were not found in 106 cases before and during ureteroscopic holmium laser lithotripsy.Logistic regression analysis of patients with ureteroscopic holmium laser lithotripsy showed that stone size(P=0.022),incarceration position(P=0.026),operation time(P=0.007),and water consumption(P=0.002)were significantly related to postoperative ureteral stenosis,Gender,age and stone location were not related to postoperative ureteral stricture(P>0.05).Case-control analysis of the two groups showed that the patients in PCNL group had the above-mentioned risk factors(P<0.01),but no ureteral stenosis occurred after operation,which was statistically significant.The thermal injury of holmium laser lithotripsy may be related to ureteral stricture,Clinical monitoring data confirm that during the URHL operation,the temperature of the outlet nearest to the operative area averaged 9.5? higher than the backwater temperature,higher than that of the perfusion fluid 10.3?.After low perfusion and long time striking,the temperature of the return water and the outlet will increase significantly.The temperature of the outlet can reach 35.7? under the condition of no perfusion with 20 W holmium laser for about 60 seconds striking.For those patients with the above risk factors,the average return water temperature which close to the operative area was only 1.6? higher than that of the perfusion fluid when undergoing PCNL operation.The same power of holmium laser continued gravel for about 350 seconds and the backwater temperature was only 25.1?.Conclusion:The risk of ureteral stricture after ureteroscopic holmium laser lithotripsy increased with the increase of stone position,stone diameter,operation time and water consumption.The stone size is highly related to the occurrence of ureteral stricture,because of the positive correlation between operation time,water consumption and stone size in ureteroscopic holmium laser lithotripsy.Especially in the treatment of large stones in the upper ureter,in order to prevent stones from moving upward and returning to the kidney,ureteroscopy is placed in a high position with a low perfusion circulation.During the treatment,local high temperature in the operation area is more likely to occur,which will damage the ureteral mucosa and lead to ureteral stenosis.However,percutaneous nephrolithotripsy with holmium laser has no such limitation.During the operation,the perfusion rate is constant,and the high temperature in the operation area will not appear after a long time of holmium laser percussion.Therefore,in the treatment of large upper segment stones,narrow operation space and insufficient circulating water flow,as well as long-term holmium laser percussion leading to local ureteral thermal injury,may be one of the main reason for the increased incidence of ureteroscopic holmium laser lithotripsy stenosis.It is suggested that percutaneous nephroscopy should be used to reduce or avoid the complications in these cases.