Postprocedure complications haunt liver RFA

Interventional radiologists need to keep a careful eye on patients undergoing radiofrequency ablation of liver tumors and to monitor some ablation devices to keep the risk of abscess low, according to a study published in the June issue of the American Journal of Roentgenology.

RFA has established a reputation in clinical practice for efficacy and safety with limited complications. Liver abscesses, however, could lead to fatal episodes.

Radiologists Dr. Dongil Choi and colleagues at the Sungkyunkwan University School of Medicine's Samsung Medical Center in Seoul looked into the frequency and risks associated with liver abscess formation after liver RFA. They enrolled over a four-year period 603 patients with 831 hepatocellular carcinomas 5 cm or smaller.

They found that liver abscesses particularly affected patients with previous biliary conditions and those with tumors treated by other means. Some patients treated with a specific type of RFA probe could also be at risk.

Thirteen patients developed liver abscesses in 14 ablated tumors. Analysis showed potential risk factors associated with liver abscess formation included biliary abnormalities leading to ascending biliary infection, tumor with retention of iodized oil from previous transcatheter arterial chemoembolization, and treatment with an internally cooled electrode system. The association was statistically significant (p = 0.0088, p = 0.040, and p = 0.016, respectively).

Most complications related to liver RFA - intraperitoneal hemorrhage, hemobilia, pleural effusion, and liver abscess - are treated conservatively with limited morbidity and mortality. But the clinical literature reports consistently on the preeminence of liver abscess and its related risks.

Though the condition's genesis post-RFA remains obscure, bacterial contamination in the zone of coagulation necrosis may be one of the culprits. Thermal injury may connect the ablation zone with the bile ducts, easing the invasion of enteric bacteria from the gallbladder.

Decreased blood flow during embolization-assisted RFA procedures and the oil content in tumors may enhance thermal destruction. But the same oil content may induce infection. And there is reason to suspect the greater generator power of the internally cooled probes could increase risks.

Physicians could resort to the prophylactic use of antibiotics in high-risk patients, as well as a meticulous aseptic protocol and closer monitoring during and after RFA for prevention or early detection of abscesses, investigators said.

The study has several design limitations, including possible underestimation of the frequency of liver abscesses after RFA.

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