Radiofrequency Ablation, Liver


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Radiofrequency Ablation, Liver

Synonym/acronym: RFA, RF ablation.

Common use

To assist in treating tumors of the liver that are too small for surgery or have poor response to chemotherapy.

Area of application

Liver.

Contrast

Done without contrast.

Description

One minimally invasive therapy to eliminate tumors in organs such as the liver is called radiofrequency ablation (RFA). This technique works by passing electrical current in the range of radiofrequency waves between the needle electrode and the grounding pads placed on the patient’s skin. A special needle electrode is placed in the tumor under the guidance of an imaging method such as ultrasound (US), computed tomography (CT) scanning (with or without iodinated contrast), or magnetic resonance imaging (MRI). A radiofrequency current is then passed through the electrode to heat the tumor tissue near the needle tip and to ablate, or eliminate, it. The current creates heat around the electrode inside the tumor, and this heat spreads out to destroy the entire tumor but little of the surrounding normal liver tissue. The heat from radiofrequency energy also closes up small blood vessels, thereby minimizing the risk of bleeding. Because healthy liver tissue withstands more heat than a tumor, RFA is able to destroy a tumor and a small rim of normal tissue about its edges without affecting most of the normal liver. The dead tumor cells are gradually replaced by scar tissue that shrinks over time. This approach is used in destroying liver tumors that may have failed to respond to chemotherapy or have recurred after initial surgery. If there are multiple tumor nodules, they may be treated in one or more sessions. In general, RFA causes only minimal discomfort and may be done as an outpatient procedure without general anesthesia. The procedure can be performed percutaneously, laproscopically, or by open surgery. RFA is most effective if the tumor is less than 4 cm in diameter; results are not as good when RFA is used to treat larger tumors. Similar therapy is being used to treat tumors in the kidney, pancreas, bone, thyroid, breast, adrenal gland, and lung.

This procedure is contraindicated for

  • high alertPatients who are pregnant or suspected of being pregnant, unless the potential benefits of a procedure using radiation (if CT is performed with or without contrast) far outweigh the risk of radiation exposure to the fetus.
  • high alertPatients with conditions associated with adverse reactions to contrast medium (e.g., asthma, food allergies, or allergy to contrast medium). Although patients are still asked specifically if they have a known allergy to iodine or shellfish, it has been well established that the reaction is not to iodine, in fact an actual iodine allergy would be very problematic because iodine is required for the production of thyroid hormones. In the case of shellfish, the reaction is to a muscle protein called tropomyosin; in the case of iodinated contrast medium, the reaction is to the noniodinated part of the contrast molecule. Patients with a known hypersensitivity to the medium may benefit from premedication with corticosteroids and diphenhydramine; the use of nonionic contrast or an alternative noncontrast imaging study, if available, may be considered for patients who have severe asthma or who have experienced moderate to severe reactions to ionic contrast medium.
  • high alertPatients with conditions associated with preexisting renal insufficiency (e.g., renal failure, single kidney transplant, nephrectomy, diabetes, multiple myeloma, treatment with aminoglycosides and NSAIDs) because iodinated contrast is nephrotoxic.
  • high alertElderly and compromised patients who are chronically dehydrated before the test, because of their risk of contrast-induced renal failure.
  • high alertPatients with the presence of large or numerous tumors (studies show that RFA is most successful if fewer than 3 tumors are present and each lesion is not greater than 3 cm in size; ablation of tumors that occupy greater than 40% of the liver may not leave sufficient liver capacity to support normal function).
  • high alertPatients with metastasis to the bile duct or surrounding hepatic vessel.
  • high alertPatients with bile duct or major vessel invasion.
  • high alertPatients with significant extrahepatic disease.
  • high alertPatients with bleeding disorders who are receiving an arterial or venous puncture, because the site may not stop bleeding.

Indications

  • Ablation of metastases to the liver
  • Ablation of primary liver tumors, with hepatocellular carcinoma
  • Therapy for multiple small liver tumors that are too spread out to remove surgically
  • Therapy for recurrent liver tumors
  • Therapy for tumors that are less than 2 in. in diameter
  • Therapy for tumors that have failed to respond to chemotherapy
  • Therapy for tumors that have recurred after initial surgery

Potential diagnosis

Normal findings

  • Decrease in tumor size
  • Normal size, position, contour, and texture of the liver

Abnormal findings related to

    N/A

Critical findings

    N/A

Interfering factors

  • Factors that may impair clear imaging

    • Metallic objects (e.g., jewelry, rings, surgery clips) within the examination field, which may inhibit organ visualization and cause unclear images.
    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status.
  • Other considerations

    • Failure to follow dietary restrictions and other pretesting preparations before the procedure may cause the procedure to be canceled or repeated.
    • Consultation with a health-care provider (HCP) should occur before the procedure for radiation safety concerns regarding younger patients or patients who are lactating. Pediatric & Geriatric Imaging Children and geriatric patients are at risk for receiving a higher radiation dose than necessary if settings are not adjusted for their small size. Pediatric Imaging Information on the Image Gently Campaign can be found at the Alliance for Radiation Safety in Pediatric Imaging (www.pedrad.org/associations/5364/ig/).
    • Risks associated with radiation overexposure can result from frequent x-ray procedures. Personnel in the room with the patient should wear a protective lead apron, stand behind a shield, or leave the area while the examination is being done. Personnel working in the examination area should wear badges to record their level of radiation exposure.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in assessing liver function.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex, anesthetics, contrast medium, or sedatives.
  • Obtain a history of the patient’s hepatobiliary system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results, including barium examinations.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including anticoagulant therapy, aspirin and other salicylates, herbs, nutritional supplements, and nutraceuticals, especially those known to affect coagulation (see Effects of Natural Products on Laboratory Values online at DavisPlus). Such products should be discontinued by medical direction for the appropriate number of days prior to a surgical procedure. Note the last time and dose of medication taken.
  • Note that if iodinated contrast medium is scheduled to be used in patients receiving metformin (Glucophage) for non-insulin-dependent (type 2) diabetes, the drug should be discontinued on the day of the test and continue to be withheld for 48 hr after the test. Iodinated contrast can temporarily impair kidney function, and failure to withhold metformin may indirectly result in drug-induced lactic acidosis, a dangerous and sometimes fatal side effect of metformin related to renal impairment that does not support sufficient excretion of metformin.
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that a sedative and/or analgesia will be administered to promote relaxation and reduce discomfort prior to the needle electrode insertion. Explain that any discomfort with the needle electrode will be minimized with local anesthetics and systemic analgesics. Inform the patient that the procedure is performed in the radiology department by an HCP, with support staff, and takes approximately 30 to 90 min.
  • Explain that an IV line may be inserted to allow infusion of IV fluids such as normal saline, anesthetics, sedatives, contrast medium, or emergency medications.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined prior to the procedure.
  • This procedure may be terminated if chest pain or severe cardiac arrhythmias occur.
  • Instruct the patient to fast and restrict fluids for 8 hr prior to the procedure. Instruct the patient to avoid taking anticoagulant medication or to reduce dosage as ordered prior to the procedure. Protocols may vary among facilities.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.

Intratest

  • Potential complications:
  • Complications related to the ablation are rare but may include brief or long-lasting shoulder pain, inflammation of the gallbladder, damage to the bile ducts with resulting biliary obstruction, thermal damage to the bowel, thermal damage to surrounding tissue resulting in cellulitis, hemorrhage, or flu-like symptoms that appear 3 to 5 days after the procedure and last for approximately 5 days.

  • Establishing an IV site and injecting contrast medium by catheter are invasive procedures. Complications are rare but do include risk for allergic reaction related to contrast reaction; bleeding from the puncture site related to a bleeding disorder, or the effects of natural products and medications known to act as blood thinners; hematoma related to blood leakage into the tissue following needle insertion; or infection that might occur if bacteria from the skin surface is introduced at the puncture site.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure that the patient has complied with dietary, fluid, and medication restrictions and pretesting preparations.
  • Ensure that the patient has removed all external metallic objects from the area to be examined prior to the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Have emergency equipment readily available.
  • Administer ordered prophylactic steroids or antihistamines before the procedure if the patient has a history of allergic reactions to any substance or drug.
  • Instruct the patient to void and change into the gown, robe, and foot coverings provided.
  • Instruct the patient to cooperate fully and to follow directions. Instruct the patient to remain still throughout the procedure because movement produces unreliable results.
  • Record baseline vital signs and assess neurological status. Protocols may vary among facilities.
  • Establish an IV fluid line for the injection of saline, sedatives, contrast medium, or emergency medications.
  • Administer an antianxiety agent, as ordered, if the patient has claustrophobia. Administer a sedative to a child or to an uncooperative adult, as ordered.
  • Place electrocardiographic electrodes on the patient for cardiac monitoring. Establish baseline rhythm; determine if the patient has ventricular arrhythmias.
  • Place the patient in the supine position on an examination table. Cleanse the selected area, and cover with a sterile drape.
  • A local anesthetic is injected at the site, and a needle electrode is inserted under ultrasound, CT, or MRI guidance.
  • A radiofrequency current is passed through the needle electrode, and the tumor is ablated.
  • Instruct the patient to take slow, deep breaths if nausea occurs during the procedure. Monitor and administer an antiemetic agent if ordered. Ready an emesis basin for use.
  • The needle electrode is removed, and a pressure dressing is applied over the puncture site.
  • Observe/assess the needle electrode insertion site for bleeding, inflammation, or hematoma formation.
  • Monitor the patient for complications related to the procedure (e.g., allergic reaction, anaphylaxis, bronchospasm).

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Instruct the patient to resume usual diet, fluids, medications, and activity, as directed by the HCP.
  • Monitor vital signs and neurological status every 15 min for 1 hr, then every 2 hr for 4 hr, and as ordered. Take temperature every 6 hr for 24 hr. Compare with baseline values. Notify the HCP if temperature is elevated. Protocols may vary among facilities.
  • Observe for delayed allergic reactions, such as rash, urticaria, tachycardia, hyperpnea, hypertension, palpitations, nausea, or vomiting.
  • Instruct the patient to immediately report symptoms such as fast heart rate, difficulty breathing, skin rash, itching, chest pain, persistent right shoulder pain, or abdominal pain. Immediately report symptoms to the appropriate HCP.
  • Instruct the patient to immediately report bile leakage, inflammation, any pleuritic pain, persistent right shoulder pain, or abdominal pain.
  • Observe/assess the needle electrode insertion site for bleeding, inflammation, or hematoma formation.
  • Instruct the patient in the care and assessment of the site.
  • Instruct the patient to apply cold compresses to the puncture site as needed to reduce discomfort or edema.
  • Instruct the patient to maintain bed rest for 4 to 6 hr after the procedure or as ordered.
  • Recognize anxiety related to test results, and be supportive of impaired activity related to physical activity. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include angiography abdomen, AST, biopsy liver, CT liver, MRI abdomen, and US liver and biliary system.
  • Refer to the Hepatobiliary System table at the end of the book for related tests by body system.