Malignant liver tumors: treatment with percutaneous microwave ablation--complications among cohort of 1136 patients.

PURPOSE To report the complications for percutaneous microwave (MW) ablation for the treatment of malignant liver tumors and the possible risk factors for complications in a large series of patients. MATERIALS AND METHODS The study was approved by the institutional review board; informed consent was waived because of the retrospective design. Over a 13-year period, 1136 patients with 1928 malignant liver tumors underwent ultrasonographically guided percutaneous MW ablation (583 with a noncooled-shaft antenna and 553 with a cooled-shaft antenna). A total of 3697 MW ablation sessions (average, 1.8 sessions per patient) were performed. Mortality and treatment-related major and minor complications were documented. Data were subsequently analyzed to determine whether the major complication rate was related to antenna type, tumor size, tumor location, or number of MW sessions. RESULTS Two deaths not directly attributable to MW ablation were encountered. Major complications occurred in 30 (2.6%) patients and included liver abscess and empyema (n = 5), bile duct injury (n = 2), perforation of the colon (n = 2), tumor seeding (n = 5), pleural effusion requiring thoracentesis (n = 12), hemorrhage requiring arterial embolization (n = 1), and skin burn requiring resection (n = 3). Minor complications included fever; pain; asymptomatic pleural effusion, gallbladder wall thickening, and arterioportal shunt; small stricture of the bile duct; and skin burn requiring no treatment. Use of noncooled-shaft antenna and an increased number of MW ablation sessions were associated with a higher rate of major complications (P < .05). CONCLUSION MW ablation is a well-tolerated technique with an acceptably low rate of major complications for treatment of malignant liver tumors. Use of a cooled-shaft antenna, as well as fewer MW sessions, may help minimize major complications.