Immediate unplanned hospital admission after outpatient ureteroscopy for stone disease.

PURPOSE: Medicare recently changed reimbursement for ureteroscopy, encouraging migration to ambulatory surgical centers. To our knowledge the risk of immediate unplanned hospital admission, which may discourage ureteroscopy at ambulatory surgical centers, is unknown. We determined the rate of immediate unplanned hospital admission, identified factors associated with admission and developed a risk stratification tool to assist with location selection for outpatient ureteroscopy. MATERIALS AND METHODS: We retrospectively reviewed the records of 1,798 consecutive outpatient ureteroscopic procedures for urolithiasis performed from 1998 to 2008 at our institution. Patients requiring immediate hospital admission were matched 1 to 3 by provider, gender and date with controls who did not require admission. Patient demographics, comorbid conditions, stone history and burden, and operative technique were assessed for impact on admission by bivariate and multivariate logistic regression. A scoring system was developed and estimated admission rates were calculated. RESULTS: There were 70 immediate unplanned admissions (3.9%). Based on multivariate analysis the factors associated with unplanned admission were any previous admission related to stones (p <0.001), history of psychiatric illness (p = 0.016) and bilateral procedure (p = 0.019). Patients with distal ureteral stones were less likely to require admission (p = 0.026). One point was added for each positive factor and 1 was subtracted for a distal ureteral stone. A risk factor score of 2 or greater in 9% of the cohort was associated with an estimated 20.0% admission rate while lower scores in 91% of the cohort were associated with a 2.9% admission rate. CONCLUSIONS: Readily identifiable factors can stratify the risk of unplanned hospital admission and help guide the selection of the most appropriate facility for outpatient ureteroscopy.