Percutaneous Microwave Ablation of Hepatic Tumors: Prospective Evaluation of Postablation Syndrome and Postprocedural Pain

PurposeTo prospectively investigate the frequency and severity of postablation syndrome (PAS) and postprocedural pain in a cohort of patients undergoing hepatic microwave ablation.Materials and MethodsFrom March 2009 to November 2011, 54 consecutive patients undergoing microwave ablation for liver tumors were enrolled. A questionnaire was administered to investigate PAS and pain at 1, 7, and 40 days after ablation. Four patients did not complete all three questionnaires and were excluded from the analysis. Additionally, laboratory tests with results known to significantly increase or decrease after ablation were performed, and ablation parameters were recorded. Potential predictors of PAS and pain at 1 and 7 days were evaluated by a logistic regression model.ResultsFifty patients underwent a single microwave ablation session, 33 for hepatocellular carcinoma (HCC) and 17 for liver metastasis. Median ablation volumes on computed tomography were 31 cm³ for HCC and 42 cm³ for metastasis. Sixty percent of patients experienced PAS in the first week. Aspartate aminotransferase (AST) levels after ablation were significantly associated with PAS during postprocedure days 1–7. Median visual analog scale scores for pain at the puncture site were 1 and 0.24 at 1 and 7 days, respectively. The risk of having at least moderate pain in the first week was significantly related to ablation volume and time and postablation increase in AST level.ConclusionsThe incidence and severity of PAS with hepatic microwave ablation is similar to that reported for radiofrequency ablation, with the best predictive factor being postablation AST level elevation. Postablation pain was best predicted by total ablation volume and AST level.