Risk factors for perinephric hematoma formation after shockwave lithotripsy: a matched case-control analysis

To determine the incidence of and evaluate the potential risk of a symptomatic perinephric hematoma (PNH) after shockwave lithotripsy (SWL) with the Storz Modulith SLX-F2 device.

Patient and treatment-related data from 6172 SWL treatments for proximal ureteral and kidney stones were collected prospectively from April 2006 to August 2010. Patients in whom signs or symptoms of a PNH developed after SWL were investigated with imaging studies. Each patient identified with a PNH was matched with four controls using sex, age (±5 years), shockwave rate, energy and number, and no SWL within the previous 6 months as the matching variables. The baseline characteristics of the 21 cases and 84 controls were compared using the Student t test. The independent variables of hypertension (intraoperative value >140/90 mm Hg), anticoagulant/antiplatelet drugs, obesity (body mass index ≥30), and diabetes were compared using a conditional logistic regression analysis. The dependent variable was hematoma.

A PNH developed after SWL with the Storz Modulith SLX-F2 device in 21 (0.34%) adult patients (19 men, 2 women) with a mean age of 55.2 years. Significant risk factors identified included intraoperative hypertension (hazard ratio [HR] 3.302, 1.066-10.230, P=0.0384) and anticoagulant/antiplatelet medications (HR 4.198, 1.103-15.984, P=0.0355). Diabetes (P=0.1043) and obesity (P=0.1021) were not associated with PNH.

A clinical PNH occurred in less than 1% of our population. This is consistent with reports from earlier generation devices. Risk factors identified for hematoma formation were intraoperative hypertension and the use of anticoagulant/antiplatelet drugs.