FAILED PERCUTANEOUS BALLOON DILATION FOR RENAL ACCESS: INCIDENCE AND RISK FACTORS ANDREW B. JOEL, JONATHAN N. RUBENSTEIN, MICHAEL H. HSIEH, TOM CHI, MAXWELL V. MENG, AND MARSHALL L. STOLLER ABSTRACT Objectives. To present our experience using balloon dilation and discuss secondary techniques to establish a percutaneous tract when balloon dilation fails. Balloon dilation is a safe and effective method to achieve percutaneous renal access, but it is not uniformly successful. Also, the failure rate and risk factors have not been well documented. Methods. We retrospectively reviewed our last 99 consecutive percutaneous renal procedures using a balloon system as our initial dilation modality. In all cases, the urologist achieved needle access. We determined the balloon failure rate, relationship to prior renal surgery and other patient-related factors, and success rate using secondary techniques of tract dilation. Results. The balloon did not adequately dilate a tract in 17 (17% failure rate) of 99 cases. The risk factors for failure included a history of prior ipsilateral renal surgery (25% failure rate versus 8% without surgery) and subcostal compared with supracostal puncture (18% versus 9% failure rate). The failure rate was not increased when stratified by laterality, stone composition, stone size and location, or history of ipsilateral renal infection. Amplatz dilators were used in 16 refractory cases and were successful in 15. Metal Alken dilators were successfully used in 2 patients. Conclusions. The balloon dilation system is commonly used as the primary modality to establish percuta- neous renal access. Although safe and effective (83%), the success rate drops dramatically in patients with prior ipsilateral renal surgery. Knowledge and skill with alternative dilation systems, such as Amplatz or metal Alken dilators, are necessary to successfully gain entry into all renal collecting systems. UROLOGY 66: 29–32, 2005. © 2005 Elsevier Inc. P ercutaneous renal surgery has become the pre- ferred treatment method for a variety of renal conditions. The choice of the nephrostomy tract dilation technique is important to minimize the risk of complications such as bleeding and perfo- ration of the collecting system. Commonly used devices include flexible serial dilating Amplatz- type dilators, 1 reusable telescoping metal Alken- type dilators, 2 and high-pressure balloon sys- tems. 3,4 Balloon dilation is believed by many to be the most rapid, easiest to use, and safest tech- nique. 5 It can be performed in one step, resulting in decreased radiation exposure to the patient and physicians. By radially dilating, rather than relying on longitudinal vector forces such as in other methods, dilation can occur without repetitive trauma, decreasing the risk of collecting system injury and hemorrhage. 6 However, balloon dila- tion is not uniformly effective. The failure rate and risk factors for failure have not been well docu- mented. We reviewed the results of our last 99 consecutive percutaneous renal procedures to de- termine the success and failure rates of balloon dilation and the need to perform secondary tech- niques to establish percutaneous renal access when balloon dilation failed. MATERIAL AND METHODS We retrospectively reviewed the case logs from our last 99 consecutive percutaneous renal procedures on 91 patients performed by one surgeon for stone and nonstone indications. In all cases, surgeon-directed needle access was achieved into the desired calix under the same anesthetic. In each case, a balloon dilating system was used as the primary method for From the Department of Urology, University of California, San Francisco, School of Medicine, San Francisco, California Reprint requests: Marshall L. Stoller, M.D., Department of Urology, University of California, San Francisco, School of Med- icine, 400 Parnassus Avenue, A-610, San Francisco, CA 94143. E-mail: Mstoller@urol.ucsf.edu Submitted: December 8, 2004, accepted (with revisions): Feb- ruary 18, 2005 ADULT UROLOGY © 2005 ELSEVIER INC. 0090-4295/05/$30.00 ALL RIGHTS RESERVED doi:10.1016/j.urology.2005.02.018 29