Endourology and Stones Incidence and Predictors for Ipsilateral Hydronephrosis Following Ureteroscopic Lithotripsy Meredith L. Barbour and Jay D. Raman OBJECTIVE PATIENTS AND METHODS
RESULTS
CONCLUSION
To review our experience in using ureteroscopy (URS) with lithotripsy for renal or ureteral calculi to determine the incidence and predictors of postprocedural ipsilateral hydronephrosis. Records of 324 URS cases for renal or ureteral calculi with imaging performed 4-12 weeks postprocedure were reviewed. Ipsilateral hydronephrosis was determined by computed tomography scan or renal ultrasound. Univariate and multivariate analyses determined the factors associated with hydronephrosis. 176 men and 148 women with a median age of 50 years were included. Median stone size was 6 mm and operative duration was 60 minutes; 30% of patients had multiple calculi; and 35% had undergone a prior ipsilateral URS. Overall, 49 of 324 patients (15%) had evidence of hydronephrosis, with 65% of these patients having symptoms and 40% requiring ancillary procedures. On multivariate analysis, increasing stone diameter (odds ratio [OR] 8.9, 95% confidence interval [CI] 1.9-23.8, P ¼ .03), prior ipsilateral URS (OR 7.7, 95% CI 1.8-28.2, P ¼ .006), longer operative duration (OR 6.5, 95% CI 1.8-16.3, P ¼ .02), and renal colic symptoms (OR 48.3, 95% CI 14.7-71.4, P 2 months. Intraoperative perforation or extravasation was noted in 7 patients (2%) with median stent duration postprocedure being 7 days (range, 4-31). Mean stone size of largest target stone was 6.7 mm and 30% of patients had multiple stones. The stone-free rate on follow-up imaging was 73.4% (238 of 324 patients). Overall, 49 of 324 patients (15%) had evidence of ipsilateral hydronephrosis between 4 and 12 weeks following stent removal. For obtaining imaging, 32 of these 49 patients (65%) had symptoms as the impetus. Identified causes of post-URS abnormal imaging included suspected edema (without anatomic obstruction) in 26 patients, obstructing residual stone fragments in 21, and stricture disease in 2. Of the patients with suspected edema, the median interval from URS to imaging was 67 weeks, with all patients documenting resolution of hydronephrosis on imaging performed 6 months thereafter. The 2 patients with stricture disease were persistently symptomatic postprocedure with subsequent URS confirming anatomic narrowing. Univariate Analysis of Variables Associated with Abnormal Imaging The association between categorical variables of interest and hydronephrosis is highlighted in Table 2. When considering clinical and demographic factors, a history of ipsilateral stricture (OR 3.3, P ¼ .02) or prior ipsilateral ureteroscopy (OR 2.2, P ¼ .01) was associated with hydronephrosis. Conversely, other clinical or demographic factors including gender, race, age (10 year increments), body mass index (5 kg/m2 increments), and prior ipsilateral stone procedure were not associated with hydronephrosis on imaging. Regarding stone factors, the presence of multiple calculi (OR 2.55, P ¼ .004) and the maximum diameter of the largest stone (5 mm increments, OR 5.1, P ¼ .008) were both associated with hydronephrosis while additional variables including location, composition, and impaction at time of procedure failed to correlate with abnormal imaging. Furthermore, duration of impaction was also not associated with postoperative hydronephrosis (7/44 [16%] impacted 2 months vs 5/17 [29%] impacted for >2 months [P ¼ .29]). Longer operative duration (30 min increments, OR 1.01, P ¼ .001), use of laser lithotripsy (OR 2.5, P ¼ .04), failure to use basket extraction (OR 2.6, P ¼ .04), and longer stent duration (1 day increment, OR 1.02, P ¼ .03) were all associated with hydronephrosis. When UROLOGY
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(-), 2015
Table 1. Demographic, operative, and stone characteristics in 324 patients undergoing URS Variable of Interest Clinical/Demographic Mean age (yrs) SD Gender Male Female Mean BMI SD Race Caucasian Non-Caucasian History of prior ipsilateral stone procedure No Yes History of prior ipsilateral ureteroscopy No Yes History of ipsilateral stricture No Yes Operative Mean OR time (min) SD Type of ureteroscope Rigid alone Flexible alone Combination Ureteral dilation No Yes Access sheath No Yes Laser lithotripsy No Yes Basket extraction No Yes Complication (perforation or extravasation) No Yes Stone Mean maximum diameter largest calculi (mm) SD Location of stones (kidney vs ureter) Kidney Ureter Both Impacted stone No Yes Pre-URS hydronephrosis No Yes Number of calculi Single Multiple Primary stone composition Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Other
No. (%) 50.2 15.4 176 (54) 148 (46) 32.8 10.3 295 (91) 29 (9) 99 (31) 225 (69) 206 (65) 111 (35) 304 (94) 20 (6) 61.5 32.7 121 (38) 132 (41) 69 (21) 222 (69) 101 (31) 248 (77) 73 (22) 87 (27) 237 (73) 27 (8) 297 (92) 317 (98) 7 (2) 6.7 3.1 98 (30) 203 (63) 23 (7) 263 (81) 61 (19) 230 (71) 94 (29) 227 (70) 96 (30) 135 25 67 14 4
(55) (10) (27) (6) (2)
BMI, body mass index; OR, odds ratios; SD, standard deviation; URS, ureteroscopy.
UROLOGY
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(-), 2015
considering URS fragmentation technique, 198 patients had fragmentation with complete extraction vs 126 with fragmentation and extraction of some fragments with expected spontaneous stone passage. Using these criteria, 26/198 (13%) with fragmentation and/or complete extraction vs 23/126 (18%) with fragmentation and/or incomplete extraction had postprocedure hydronephrosis (P ¼ .26). Additionally, other intraoperative variables including type of ureteroscope, ureteral dilation, use of an access sheath, intraoperative perforation or extravasation, and use of a stent did not correspond to ipsilateral postprocedure hydronephrosis. Finally, symptomatic presentation at the time of imaging (OR 50.0, P
RESULTS
CONCLUSION
To review our experience in using ureteroscopy (URS) with lithotripsy for renal or ureteral calculi to determine the incidence and predictors of postprocedural ipsilateral hydronephrosis. Records of 324 URS cases for renal or ureteral calculi with imaging performed 4-12 weeks postprocedure were reviewed. Ipsilateral hydronephrosis was determined by computed tomography scan or renal ultrasound. Univariate and multivariate analyses determined the factors associated with hydronephrosis. 176 men and 148 women with a median age of 50 years were included. Median stone size was 6 mm and operative duration was 60 minutes; 30% of patients had multiple calculi; and 35% had undergone a prior ipsilateral URS. Overall, 49 of 324 patients (15%) had evidence of hydronephrosis, with 65% of these patients having symptoms and 40% requiring ancillary procedures. On multivariate analysis, increasing stone diameter (odds ratio [OR] 8.9, 95% confidence interval [CI] 1.9-23.8, P ¼ .03), prior ipsilateral URS (OR 7.7, 95% CI 1.8-28.2, P ¼ .006), longer operative duration (OR 6.5, 95% CI 1.8-16.3, P ¼ .02), and renal colic symptoms (OR 48.3, 95% CI 14.7-71.4, P 2 months. Intraoperative perforation or extravasation was noted in 7 patients (2%) with median stent duration postprocedure being 7 days (range, 4-31). Mean stone size of largest target stone was 6.7 mm and 30% of patients had multiple stones. The stone-free rate on follow-up imaging was 73.4% (238 of 324 patients). Overall, 49 of 324 patients (15%) had evidence of ipsilateral hydronephrosis between 4 and 12 weeks following stent removal. For obtaining imaging, 32 of these 49 patients (65%) had symptoms as the impetus. Identified causes of post-URS abnormal imaging included suspected edema (without anatomic obstruction) in 26 patients, obstructing residual stone fragments in 21, and stricture disease in 2. Of the patients with suspected edema, the median interval from URS to imaging was 67 weeks, with all patients documenting resolution of hydronephrosis on imaging performed 6 months thereafter. The 2 patients with stricture disease were persistently symptomatic postprocedure with subsequent URS confirming anatomic narrowing. Univariate Analysis of Variables Associated with Abnormal Imaging The association between categorical variables of interest and hydronephrosis is highlighted in Table 2. When considering clinical and demographic factors, a history of ipsilateral stricture (OR 3.3, P ¼ .02) or prior ipsilateral ureteroscopy (OR 2.2, P ¼ .01) was associated with hydronephrosis. Conversely, other clinical or demographic factors including gender, race, age (10 year increments), body mass index (5 kg/m2 increments), and prior ipsilateral stone procedure were not associated with hydronephrosis on imaging. Regarding stone factors, the presence of multiple calculi (OR 2.55, P ¼ .004) and the maximum diameter of the largest stone (5 mm increments, OR 5.1, P ¼ .008) were both associated with hydronephrosis while additional variables including location, composition, and impaction at time of procedure failed to correlate with abnormal imaging. Furthermore, duration of impaction was also not associated with postoperative hydronephrosis (7/44 [16%] impacted 2 months vs 5/17 [29%] impacted for >2 months [P ¼ .29]). Longer operative duration (30 min increments, OR 1.01, P ¼ .001), use of laser lithotripsy (OR 2.5, P ¼ .04), failure to use basket extraction (OR 2.6, P ¼ .04), and longer stent duration (1 day increment, OR 1.02, P ¼ .03) were all associated with hydronephrosis. When UROLOGY
-
(-), 2015
Table 1. Demographic, operative, and stone characteristics in 324 patients undergoing URS Variable of Interest Clinical/Demographic Mean age (yrs) SD Gender Male Female Mean BMI SD Race Caucasian Non-Caucasian History of prior ipsilateral stone procedure No Yes History of prior ipsilateral ureteroscopy No Yes History of ipsilateral stricture No Yes Operative Mean OR time (min) SD Type of ureteroscope Rigid alone Flexible alone Combination Ureteral dilation No Yes Access sheath No Yes Laser lithotripsy No Yes Basket extraction No Yes Complication (perforation or extravasation) No Yes Stone Mean maximum diameter largest calculi (mm) SD Location of stones (kidney vs ureter) Kidney Ureter Both Impacted stone No Yes Pre-URS hydronephrosis No Yes Number of calculi Single Multiple Primary stone composition Calcium oxalate monohydrate Calcium oxalate dihydrate Calcium phosphate Uric acid Other
No. (%) 50.2 15.4 176 (54) 148 (46) 32.8 10.3 295 (91) 29 (9) 99 (31) 225 (69) 206 (65) 111 (35) 304 (94) 20 (6) 61.5 32.7 121 (38) 132 (41) 69 (21) 222 (69) 101 (31) 248 (77) 73 (22) 87 (27) 237 (73) 27 (8) 297 (92) 317 (98) 7 (2) 6.7 3.1 98 (30) 203 (63) 23 (7) 263 (81) 61 (19) 230 (71) 94 (29) 227 (70) 96 (30) 135 25 67 14 4
(55) (10) (27) (6) (2)
BMI, body mass index; OR, odds ratios; SD, standard deviation; URS, ureteroscopy.
UROLOGY
-
(-), 2015
considering URS fragmentation technique, 198 patients had fragmentation with complete extraction vs 126 with fragmentation and extraction of some fragments with expected spontaneous stone passage. Using these criteria, 26/198 (13%) with fragmentation and/or complete extraction vs 23/126 (18%) with fragmentation and/or incomplete extraction had postprocedure hydronephrosis (P ¼ .26). Additionally, other intraoperative variables including type of ureteroscope, ureteral dilation, use of an access sheath, intraoperative perforation or extravasation, and use of a stent did not correspond to ipsilateral postprocedure hydronephrosis. Finally, symptomatic presentation at the time of imaging (OR 50.0, P
