Hospital admission for treatment of complications after extracorporeal shock wave lithotripsy for renal stones: a study of risk factors.

The objective of this study was to determine risk factors of hospital admission for treatment of complications after extracorporeal shock wave lithotripsy (SWL). The electronic files and images of all patients who underwent SWL for treatment of renal stones between January 2011 and December 2015 were retrospectively reviewed. All patients underwent SWL with the same electromagnetic lithotripter (Dornier Lithotripot S). The data of those who needed hospital admission for treatment of complications within 30 days after SWL were compared with patients who did not require hospital admission. Compared data included patients' demographics (age, gender, BMI, ASA score, and pre-SWL stenting), renal characters (side, hydronephrosis, and solitary kidney), and stone characters (site, length, density, and previous treatment). Univariate and multivariate statistical analyses were used to identify risk factors. The study included 1179 patients. Complications that required hospital admission were observed in 108 patients (9.2%). They included obstructing steinstrasse in 91 (7.7%), peri-renal hematoma in 3 (0.25%), and fever (>38.0 °C) in 14 (1.2%). Independent risk factors on multivariate analysis were solitary kidney (OR 2.855, P = 0.017), pre-SWL stenting (RR 2.03, P = 0.044), ASA II (OR 1.965, P = 0.007), hydronephrosis (RR 1.639, P = 0.024), and stone length (RR 1.083, P < 0.001). Patients with medical co-morbidities, pre-SWL ureteral stents, large stones and those with obstructed and/or solitary renal unit are more liable to post-SWL complications that need hospital admission. The probability of hospital admission has to be explained to patients with these risk factors.