Stone volume is best predictor of operative time required in retrograde intrarenal surgery for renal calculi: implications for surgical planning and quality improvement

Abstract

Retrograde intrarenal surgery (RIRS) is highly successful at eliminating renal stones of various sizes and compositions. As urologists are taking on more complex procedures using RIRS, this has led to an increase in operative (OR) times. Our objective was to determine the best predictor of OR time in patients undergoing RIRS. We retrospectively reviewed the records of patients undergoing unilateral RIRS for solitary stones over a 10 year time span. Stones were fragmented and actively extracted using a basket. Variables potentially affecting OR time such as patient age, sex, BMI, lower pole stone location, volume, Hounsfield units (HU), composition, ureteral access sheath (UAS) use, and pre-operative stenting were collected. Multivariable linear and stepwise regression was used to evaluate the predictors of OR time. There were 118 patients that met inclusion criteria. The median stone volume was 282.6 mm (IQR 150.7-644.7) and the mean OR time was 50 min (±25.9 SD). On univariate linear regression, stone volume had a moderate correlation with OR time (y = 0.022x + 38.2, r = 0.363, p< 0.01). On multivariable stepwise regression, stone volume had the strongest impact on OR time, increasing time by 2.0 min for each 100 mm increase in stone volume (p < 0.001). UAS added 13.5 (SE 3.9, p = 0.001) minutes and renal lower pole location added 9 min (SE 4.3, p = 0.03) in each case they were used. Pre-operative stenting, HU, calcium oxalate stone composition, sex, and age had no significant effect on OR time. Amongst the main stone factors in RIRS, stone volume has the strongest impact on operative time. This can be used to predict the length of the procedure by roughly adding 2 min per 100 mm increase in stone volume.

Factors affecting the operating time for complete cyst excision and Roux-en-Y hepaticojejunostomy in paediatric cases of congenital choledochal malformation: a retrospective case study in Southeast China

“… 14 15 Sorokin et al reported that increased postoperative complications were associated with the prolonged operating time. 16 Qiao et al reported similar findings on assessing 956 paediatric cases with CCM, in which all the patients had undergone complete cyst excision and Roux-en-Y hepaticojejunostomy. 11 The mean operating time in the said study was 3.52 hours (range 2.21–5.75 hours).…”

Correlation of Operative Time with Outcomes of Ureteroscopy and Stone Treatment: a Systematic Review of Literature

“…Whilst URS is well known to be a safe and effective way of treating renal and ureteral stones, longer operative times are associated with an increased risk of fever, bleeding, and ureteral perforation [17,27]. This could be explained by larger stone volume and complex stones [34] demanding a more difficult and lengthy procedures [35]. Ito et al examined operative times of 407 procedures, reviewing the total operative time and subdividing this into times before and after fragmentation [23].…”

Threshold Point of the Total Stone Volume Matter on Decision of Flexible Ureteroscopy

“…Although the guidelines maintain this accustomed inaccuracy; a few previous studies used a volumetric measurement to evaluate the kidney stone. 26 Ito et al studied that larger stone volume prolonged the operative time. 27 Another research of the same group mentioned that stone volume is independent predictors of SFR.…”