Factors affecting the operation time in percutaneous nephroli̇thotomy

Objective: To analyze parametres influential on operative times in patients who underwent unilateral PNL because of renal stone in detail, and predict complications that might occur during prolonged operations. Material and Methods: This study was performed on 251 patients who had hospitalized, and undergone PNL operations between January 2012, and December 2012 in the Dicle University Faculty of Medicine, Department of Urology with the indication of renal stones. During the study period 198 patients who complied with the eligibility criteria, and whose medical records were regularly kept were included in the study. Age, gender, previous surgery (if any), height, body weight, stone burden, and location, operative, and scopy times, renal access site, type of dilator used, expertise of the surgeon, caliber of the nephroscope used, diameter of the nephrostomy tract, dwell time of the nephrostomy tube, number of pneumatic shock waves delivered, perioperative stone-free state, postoperative complications, and length of hospital stay were recorded, and evaluated. Results: Study population consisted of 105 male (53%), and 93 female (47 %) patients with a mean age of 33.8±2112 years, and BMI of 24.15±5.77. Preoperatively, double-J stents were implanted in 31 patients (15.7). Mean hospital stay was 4.07±2.54 days. Diameters of the postoperatively inserted nephrostomy tubes ranged between 0-24F (median, 17.47F). Mean nephrostomy tube dwell time was 2.05±0.98 days. Pre-, and postoperative Htc values were 38.64±4.97, and 36.66±4.56 percent, respectively. Mean number of delivered pneumatic shock waves were 648.41±988.80. Postoperative evaluation revealed complete stone clearance in 143 (72.2 %) patients, clinically insignificant residual fragments in 6 (3.1 %), and residual stones in 49 (24.7 %) patients. Mean operative time was 85.03 minutes. While it was 85.15 min for the right, and 84.73 min for the left kidney. A statistically significant difference was not found between both sides as for operative times. Median operative time for the patients without preoperative renal ectasia was 61.75 min, while it was 76,77 min, 90.23 min, 101.11min, and 90.56 min for patients with Grade 1,2,3,and 4 renal ectasias, respectively. Relatively prolonged operative times were observed in patients with grade 2, 3, and 4 renal ectasias. Average operative times were estimated for patients (n=21) with a single calyceal stone (60 min), pelvic stone (n=32 patients, 67.34 min), single calyceal, and a pelvic stone ( n=74; 71.82 min), multiple calyceal, and pelvic Stones (n= 56; 107.05 min), and staghorn stones (n=15; 140.67 min). As is indicated, operative times were statistically significantly longer in patients with staghorn or multiple pelviocalyceal stones when compared with stones in other locations. Stone-free status was achieved in 19 of 20 (95 %) patients without preoperative hydronephrosis, in 102 out of 132 (77.3 %) cases with grade 1-2, and in 60.9 % (28/46) of the patients with grade 3-4 renal ectasias. Preoperatively higher grade hydronephrosis led to statistically significantly lower stone clearance rates. Conclusion: In our study, we have observed that increased stone burden, presence of staghorn stones, multiple calyceal stones, increased hydronephrosis statistically significantly prolonged operative times. PNL achieved lower stone-free rates in patients with hydronephrotic collecting systems, and previous renal surgery led to an increase in complication rates. Besides, operative, and scopy times were directly proportional. Longer operative times was not associated with higher complication rates.