Myoglobinuria after laparoscopic radiofrequency ablation of liver tumors.

BACKGROUND: There are scant data in the literature about myoglobinuria after radiofrequency ablation (RFA) of liver tumors. The aim of this study is to analyze the incidence and identify the risk factors involved in this complication after RFA. PATIENTS AND METHODS: An initial case of myoglobinuria and acute kidney injury (AKI) during laparoscopic liver RFA after 10 years of the liver ablation program led to the design of this study. Prospective data were collected on 41 consecutive patients undergoing laparoscopic RFA at our institution over a 9-month period. Urine myoglobin, serum creatinine kinase, and serum creatinine levels were obtained preablation and postablation. Variables were compared between patients to identify possible risk factors that might be related to this rare complication. Data are expressed as mean +/- standard error of the mean.
RESULTS: Two patients were excluded from the study due to preoperative myoglobinuria of unknown etiology. Of the remaining 39 patients, three developed dark urine with significant myoglobinuria on postoperative day 1. Two of these patients had carcinoid liver metastases; the remaining patient had a metastatic colorectal lesion. The number of tumors ablated in these patients was 14, 11, and 3 vs. 2.4 +/- 0.4 in the rest of the patients. Cumulative tumor volume was larger in the group of patients that developed the complication vs. those who did not (127.9 +/- 59.5 vs. 48 +/- 3 cm(3)). Two grounding pads were used in the three patients that had a complication vs. four pads in the rest of the patients. Dark urine was identified promptly intraoperatively and treated aggressively. All of these patients required intensive care unit (ICU) admission and had a prolonged hospital stay. Marked elevation of transaminases and creatinine kinase as well as a drop in hematocrit and platelet count was observed in patients with myoglobinuria. In our retrospective review of 706 patients that underwent liver RFA in the past 10 years, we detected 27 patients (3.8%) with ten or more lesions (11.9 +/- 0.4). None of these patients had significant elevation of serum creatinine postoperatively. In the whole series of 706 patients, 22 (3.2%) were found to have elevated creatinine after liver RFA, with return to baseline in all but seven patients in follow-up.
CONCLUSION: Myoglobinuria after liver RFA is a rare but potentially devastating complication that may lead to AKI with significant morbidity and prolonged hospital stay. Patients with large tumor volumes requiring longer ablation times need to be monitored closely for the development of this complication. The fact that this was not observed in other patients with similar tumor characteristics suggests that individual patient-related factors might play an important role.