Liver biopsy

This position paper has been approved by the AASLD and represents the position of the association. These recommendations provide a data-supported approach. They are based on the following: (1) formal review and analysis of the recently published world literature on the topic; (2) American College of Physicians Manual for Assessing Health Practices and Designing Practice Guidelines1; (3) guideline policies, including the AASLD Policy on the Development and Use of Practice Guidelines and the American Gastroenterological Association Policy Statement on Guidelines2; and (4) the experience of the authors in the specified topic. Intended for use by physicians, these recommendations suggest preferred approaches to the diagnostic, therapeutic, and preventive aspects of care. They are intended to be flexible, in contrast to standards of care, which are inflexible policies to be followed in every case. Specific recommendations are based on relevant published information. To more fully characterize the quality of evidence supporting recommendations, the Practice Guidelines Committee of the AASLD requires a Class (reflecting benefit versus risk) and Level (assessing strength or certainty) of Evidence to be assigned and reported with each recommendation (Table 1, adapted from the American College of Cardiology and the American Heart Association Practice Guidelines3).4 AASLD, American Association for the Study of Liver Diseases; AIH, autoimmune hepatitis; ALF, acute liver failure; ALT, alanine aminotransferase; ANA, antinuclear antibody; CT, computed tomography; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; HVPG, hepatic venous pressure gradient; IgG, immunoglobulin G; INR, international normalized ratio; NAFLD, nonalcoholic fatty liver disease; PBC, primary biliary cirrhosis; PSC, primary sclerosing cholangitis; PT, prothrombin time; US, ultrasound. Histological assessment of the liver, and thus, liver biopsy, is a cornerstone in the evaluation and management of patients with liver disease and has long been considered to be an integral component of the clinician's diagnostic armamentarium. Although sensitive and relatively accurate blood tests used to detect and diagnose liver disease have now become widely available, it is likely that liver biopsy will remain a valuable diagnostic tool. Although histological evaluation of the liver has become important in assessing prognosis and in tailoring treatment, noninvasive techniques (i.e., imaging, blood tests) may replace use of liver histology in this setting, particularly with regard to assessment of the severity of liver fibrosis.5, 6 Several techniques may be used to obtain liver tissue; a table including/defining specific terms has been provided in an effort to standardize terminology (Table 2). All liver biopsy techniques require specific training so as to ensure appropriate-sized specimen retrieval and the lowest rate of complications. Although liver biopsy is often essential in the management of patients with liver disease, physicians and patients may find it to be a difficult undertaking because of the associated risks. The purpose of this practice guideline is to summarize the current practice of liver biopsy and make recommendations about its performance. This guideline deals exclusively with liver biopsy as it relates to adult liver disease. Historically, liver biopsy was used almost exclusively as a diagnostic tool.7, 8 However, as the result not only of new natural history data and the introduction of many new therapies for patients with liver disease, liver biopsy and histological assessment of the liver has now taken on an important role in clinical management. Therefore, as of 2009, liver biopsy currently has three major roles: (1) for diagnosis, (2) for assessment of prognosis (disease staging), and/or (3) to assist in making therapeutic management decisions. For many diseases, clinical and/or blood-based tests suffice to establish a diagnosis (typical examples include hepatitis B [HBV] or hepatitis C virus [HCV] infection). Nonetheless, liver biopsy is often a critical component in establishing the diagnosis of many (other) forms of liver disease. Although histological assessment alone may be able to make a diagnosis on occasion (i.e., a florid duct lesion in primary biliary cirrhosis [PBC]), liver histology is typically and most appropriately considered in conjunction with the full gamut of clinical and laboratory data. Acute and chronic hepatitis, cholestatic disorders, fatty liver disease, vascular diseases, infiltrative or storage diseases, some infectious and granulomatous diseases, and other disorders may be associated with characteristic histological abnormalities that are helpful in diagnosis.9 Liver biopsy is particularly useful in patients with atypical clinical features. For example, liver histology can help distinguish between autoimmune hepatitis (AIH) and nonalcoholic fatty liver disease (NAFLD) in an obese patient with elevated levels of alanine aminotransferase (ALT), raised immunoglobulin G concentration (IgG), and/or a positive antinuclear antibody (ANA) titer. Liver histology may also be very helpful in patients with coexisting disorders such as steatosis and HCV or hemochromatosis10, 11 or an “overlap” syndrome of PBC with AIH.12 It is likely that liver biopsy will always play a role in the management of the patient with a diagnostic dilemma. This includes the patient with abnormal liver tests of unknown etiology (see below) or the patient in whom a specific liver disease has been considered, but has not yet been confirmed. Examples include patients with a variety of possible diseases, including, but not limited to hereditary disorders such as Wilson disease, alpha-1-antitrypsin disease, glycogen storage diseases, tyrosinemia, Niemann-Pick disease, amyloidosis, and others.13-26 Liver histology may also be helpful diagnostically in patients with apparent systemic diseases in which the liver appears to be involved. Microscopic examination of the liver in patients with suspected hereditary hemorrhagic telangiectasia is rarely necessary, and should probably be performed via the transvenous route, concomitant with measurement of the portosystemic pressure gradient.15 Liver histology may provide important diagnostic information in patients with acute liver failure (ALF).27 For example, liver biopsy is helpful in making a specific diagnosis in specific settings (e.g., herpes virus infection, Wilson disease, AIH, and malignancy),27, 28 which in turn may guide more specific therapy. Liver histology in patients with hepatomegaly or apparent diffuse disease may help establish a diagnosis, but whether it is clinically useful or cost effective is unknown. Examples of diffuse diseases include amyloidosis,29, 30 granulomatous hepatitis caused by any of a number of processes, and a host of other miscellaneous disorders. A further important use of liver biopsy is in assessing disease severity, notably fibrosis, which, as a precursor to cirrhosis, may predict the emergence of complications of portal hypertension and also liver-related morbidity and mortality. Evidence in the area of HCV emphasizes the role of fibrosis assessment in determining prognosis. For example, alcohol consumption, increased hepatic iron concentration, and/or hepatic steatosis, all of which are associated with more rapid fibrosis progression in patients with chronic HCV,10, 31-33 are currently assessed best by histology.34 Further, specific evidence links fibrosis and prognosis; an example of this logical relationship is that in patients with HCV infection after liver transplantation, mortality was increased in those with advanced compared to minimal fibrosis.35 Also, progression of NAFLD and eventual liver-related mortality appear to be related to the initial fibrosis stage.36 Evidence that fibrosis assessment is important in prognosis also exists in PBC; in a long-term cohort study of 160 patients with PBC, for every stage increase of fibrosis identified (on a 1–4 point fibrosis scale) on initial liver biopsy, there was a twofold increase in future complications or death (relative risk 2.4; 95% confidence interval [CI]: 1.6–3.6).37 In cases of genetic hemochromatosis, survival in patients without cirrhosis is similar to the normal control population, while mortality in those with advanced fibrosis/cirrhosis is significantly increased38 and patients with cirrhosis are at increased risk of hepatocellular cancer (HCC),38 and should be screened. Liver histology in patients with AIH may also provide prognostic information; the overall outcome for those with cirrhosis appears to be poorer than that for those without cirrhosis.39 Finally, patients with fibrosis regression may actually be protected from developing clinical complications.40 Thus, accurate assessment of liver fibrosis by histological analysis clearly provides important prognostic information. Assessment of liver histology may be particularly beneficial in patients with human immunodeficiency virus and HCV who have persistently normal ALT levels, because these patients may have significant fibrosis, which may be of prognostic importance. This allows the clinician to determine the extent of liver fibrosis and, consequently, to assess suitability for treatment.41 Currently, liver biopsy is used more than ever to develop treatment strategies. As previously emphasized, this has evolved because of the many new therapies available for patients with a variety of liver diseases. Not only can a treatment plan be instituted in a patient after a specific diagnosis is made (i.e., steroids in the setting of AIH), but among those with established liver disease, treatment may be predicated on the specific histological lesion. In the latter circumstance, therapy is usually directed at the patient with a more advanced histological stage. For example, histological analysis of the liver in patients with HCV provides information about the grade (degree of inflammation), which in turn presumably reflects to what extent the liver disease injury remains ongoing. In patients with chronic HCV-induced liver disease, treatment is often advocated for those with at least moderate to severe stages of fibrosis, but may be withheld when fibrosis is minimal or absent.42 Liver histology is also commonly used in disease monitoring of patients with AIH. First, the portal plasma cell score (a measure of portal-based plasma cell infiltrate) may predict relapse,43 and second, liver biopsy is often obtained prior to steroid dose reduction and/or discontinuation of immunosuppressive therapy altogether because the incidence of relapse is substantial in patients with evidence of residual interface hepatitis.44 Finally, there is evidence that patients with PBC with advanced fibrosis at diagnosis may respond less well to ursodeoxycholic acid than do patients with minimal or mild fibrosis, thus placing them at risk of more rapid disease progression and premature death/requirement for liver transplantation.45 For further information on the role of histological analysis in the management of individual liver diseases, please see guidelines for HCV,46 HBV,47 hemochromatosis,48 PBC,49 AIH,44 and Wilson disease.50 The diseases and situations in which liver biopsy may be indicated are listed in Tables 3 and 4. It is important to emphasize that the role of histological analysis of the liver in the management of patients with liver disease is likely to evolve over time, particularly as noninvasive modalities for assessment of fibrosis (and perhaps inflammation) are positioned more in the mainstream.5, 6 Further information on the role of liver biopsy and histological analysis in specific liver diseases is highlighted below and in published AASLD guidelines referred to above.44, 46-49 Liver biopsy has long been regarded as an important diagnostic adjunct in the evaluation of abnormal liver tests of unclear etiology—that is, after a thorough history, physical examination, biochemical, serological, and imaging investigation have failed to elucidate a diagnosis. Available data indicate that liver histology will, in a proportion of patients, point to a specific diagnosis51 and lead to a change in patient management.52, 53 In one study, histological findings were examined in 354 patients who underwent liver biopsy to investigate abnormal liver tests; 64% of biopsies revealed an element consistent with NAFLD, while other diagnoses included cryptogenic hepatitis, drug-induced liver injury, primary and secondary biliary cirrhosis, AIH, alcohol-related liver disease, primary sclerosing cholangitis (PSC), hemochromatosis, and amyloid and glycogen storage disease.53 Only 6% of patients had a normal liver biopsy, whereas 26% were found to have some degree of fibrosis and 6% of patients had cirrhosis. Patient management was modified in 18% of patients after liver biopsy, and three families were entered into a screening program for heritable liver disease.53 Thus, it was concluded that the finding of abnormal liver tests in the absence of diagnostic serology may indicate significant liver disease and histological analysis provides meaningful information. Conversely, in another study, asymptomatic adult patients with persistent (≥ 6 months) liver test abnormalities were examined (patients with a strong suspicion for a specific liver disease were excluded).52 In this study of 36 patients, a presumptive diagnosis and a preliminary management plan were documented before liver biopsy; prebiopsy diagnoses included nonalcoholic steatohepatitis (NASH; 24 patients), AIH (3 patients), PBC (2 patients), PSC (2 patients), and others (5 patients). Histological findings after liver biopsy changed the diagnosis in only 14% of cases. Thus, although the liver biopsy appeared to help confirm the diagnosis, biopsy findings infrequently altered the suspected prebiopsy diagnosis, and even more rarely altered management.52 Liver histology may also be helpful in the establishment of an unsuspected diagnosis, such as alcoholic liver disease.54, 55 Particularly in the setting of abnormal liver tests of unclear etiology, the risks and benefits of a liver biopsy should be carefully weighed, and the decision to perform a liver biopsy must be individualized. Cryptogenic cirrhosis or cirrhosis of unknown etiology is found to be the assigned diagnosis in 3%–30% of patients with cirrhosis.56, 57 Cryptogenic cirrhosis has several putative causes including NASH, silent or “burnt out” AIH, occult viral infection, and covert alcoholism. Based on well-documented serial biopsy reports demonstrating progression of prior histological NASH to cirrhosis without any continuing definitive evidence of NASH58-60 and based on extensive epidemiological data, NASH is considered one of the leading causes of cryptogenic cirrhosis in many western countries,61-63 although autoimmune disease appears to be a more common underlying disease in some parts of Europe.64, 65 Classification schemes for cryptogenic cirrhosis have been proposed on the basis of the clinical setting and on so-called residual histological findings such as foci of autoimmune-like inflammatory infiltrates versus NASH-like foci of steatosis, cellular ballooning, and glycogenated nuclei.66, 67 Indeed, a recent serial biopsy study of patients with cirrhosis who had antecedent biopsies revealing NASH support the use of these parameters as markers for prior NASH.68 Assessment of liver histology following orthotopic liver transplantation is an essential component of management in this patient population. It is often important to make a specific diagnosis in the setting of liver test abnormalities early after transplantation to investigate allograft rejection, preservation or reperfusion injury, drug-induced liver injury, (usually recurrent) viral infection, or bile duct injury. Liver biopsy is also often helpful in the setting of late allograft dysfunction,69 including to investigate the possibility of recurrence of the original disease.70 Some liver transplant programs perform liver biopsy on a protocol basis after transplantation (e.g., annually), even in those patients with normal liver tests, although compelling evidence to support this approach is lacking. In contrast, there is good evidence suggesting that fibrosis progression may be predicted by using liver histology in patients following transplantation.35, 71 In one study, liver histology obtained at 1 year after transplantation in patients with HCV infection allowed identification of patients with rapid fibrosis progression (donor age > 55 years was associated with rapid fibrosis progression and development of cirrhosis).71 In another study, patients with more advanced fibrosis stages had a greater likelihood of clinical decompensation than those with minimal or no fibrosis.35 In addition, histological assessment appears to be critical in evaluation of the donor liver immediately before it is transplanted. Macrovesicular steatosis, (occult) fibrosis, and inflammation have all been associated with poorer graft function after liver transplantation, especially in older recipients and those with chronic HCV liver disease. Some experts have recommended that donor livers with suspicious clinical histories be evaluated by sampling at least two sites.72 Importantly, while liver ultrasound has high specificity for exclusion of steatosis in apparently normal livers, both its sensitivity and negative predictive value are very low, thus limiting its utility in the diagnosis of a fatty liver.73 Liver biopsy and evaluation of hepatic histology in evaluation of healthy living related donors is controversial.74-76 In a study of 144 donor candidates who underwent liver biopsy as part of the pretransplant donor evaluation, 31 (21%) had at least one histological finding precluding liver donation (21 had steatosis and 10 had other diseases, including non–A-D hepatitis in six cases, diffuse granulomatosis in two, schistosomiasis in one, and cryptogenic fibrosis in one).74 Another study found that approximately half of presumably healthy donors had abnormal pathology results, including nearly one-third of patients with fatty changes.76 Thus, some experts believe that preoperative liver biopsy is a necessary component of the evaluation of potential living donors.74, 76 The use of liver biopsy for evaluation of focal liver disease (i.e., a lesion detected by imaging) is highly variable and difficult. Evaluation of focal liver disease is further complicated because lesions may be cystic, solid, or vascular (or combinations thereof) and because there is considerable overlap in the appearance between benign and malignant lesions. Further, use of liver biopsy almost always depends on the specific clinical scenario. For example, evaluation of mass lesions requires consideration of whether the patient has no known underlying liver disease or whether the patient has a known parenchymal liver process. Both categories of patient may require consideration of liver biopsy in establishing the correct diagnosis. Initially, cross-sectional imaging may confirm that the liver has an abnormal contour consistent with cirrhosis, and may demonstrate other features of portal venous hypertension such as splenomegaly and intra-abdominal varices. Moreover, the liver may be enlarged because of the presence of the lesion(s). In patients with underlying liver disease, especially cirrhosis, the overriding concern is with HCC. This diagnosis can be made in patients with a typical lesion (usually > 2 cm in size, with a typical vascular pattern seen with dynamic imaging techniques).77 In patients with smaller lesions, the use of liver biopsy (typically fine-needle aspiration biopsy) is controversial.78, 79 Arguments against biopsy sampling include: (1) sampling error may leave the diagnosis in doubt; (2) HCC recurrence rates after liver transplantation were significantly higher among patients with tumors larger than 3 cm, pathological tumor-node-metastasis (pTNM) I-III stage, Child class B or C cirrhosis, and alpha-fetoprotein >200 ng/mL who underwent biopsy;80 and (3) there appears to be a small, but finite risk of tumor seeding of the needle track through which the biopsy was procured (see below under contraindications).81-83 Conversely, the presence of HCC significantly alters the priority for liver transplantation, leading to the need to avoid false positive imaging studies; thus, histological confirmation may facilitate management by removing doubt. Uncertainty regarding these issues underlies the reported wide practice variation.84, 85 For specific recommendations about liver biopsy in patients with suspected HCC, see the AASLD practice guideline review on this subject.77 Part of the controversy about liver biopsy in patients with suspected HCC derives from previous limitations in therapeutic options and the lack of predictive utility of simple histological characteristics such as the degree of differentiation.86 This area is likely to change as new treatment modalities emerge (e.g., radioactive beads and anticancer biological agents) in conjunction with a better understanding of HCC biology, which might predict response. Another mass lesion that may develop in the setting of underlying liver disease is cholangiocarcinoma. Although isolated lesions may occur in otherwise normal livers, this lesion typically arises in the presence of chronic biliary tract disease, e.g., PSC or a choledochal cyst. It usually presents as a solitary lesion either involving the biliary hilum or within the hepatic parenchyma. The decision to biopsy such a lesion, assuming it is solitary, may be governed by whether surgical resection is considered feasible. If not, or the possibility of liver transplantation arises, then the lesion should be biopsied under image guidance. Any enlarged porta hepatis or other upper abdominal lymph nodes may be biopsied at the same time. It may not be possible to distinguish rare primary hepatic tumors from a more common primary lesion or a solitary metastasis solely on the basis of cross-sectional imaging and tumor markers, in which case image-guided biopsy is also necessary to confirm the diagnosis. The gastroenterologist and hepatologist, whether working in the community or in an academic setting, may anticipate referral of patients whose principal problem is the recent discovery of one or more focal hepatic lesions in the absence of underlying parenchymal/structural liver disease. This may arise after an imaging test due to specific symptoms or signs, or perhaps after imaging undertaken for reasons that may have nothing to do with the hepatic lesions. Patients who do not have parenchymal liver disease and in whom a focal hepatic lesion(s) is discovered will often have one of the abnormalities highlighted in Table 5. Virtually any of these lesions may be single or multiple, although overall, most are solitary. Generally, the most common lesions identified in patients without underlying liver disease include benign hepatic lesions, most often solitary, but on occasion multiple. For the most part, these should have sufficient distinguishing characteristics on high-quality cross-sectional imaging modalities such that liver biopsy is unnecessary. For example, a hemangioma has characteristic bright appearances on the T2-weighted magnetic resonance imaging and often displays dynamic enhancement with contrasted computed tomography (CT) imaging. Likewise, focal nodular hyperplasia is typically solitary and has a “central scar” of low attenuation. Alternatively, where hepatic adenomata are multiple and appear hypervascular on the arterial phase of triple contrast CT imaging, concern may arise for metastases from, e.g., thyroid cancer, thus making biopsy of one or more lesions mandatory. Pyogenic liver abscesses may be associated with air produced by gas-forming bacteria.87 Apparent metastatic lesion(s) without an obvious primary site may be hypoechoic either hyperattenuating or hypoattenuating (typically they are of low attenuation) on CT imaging, and should be biopsied under image guidance to confirm the diagnosis. If there is any doubt as to whether the patient has underlying parenchymal disease, then biopsy specimens should also be taken from site(s) distant from the lesion(s) also. The approach to patients with mass lesions will vary depending on the patient's overall clinical picture. Table 6 summarizes some of the more common liver lesions, and their imaging appearances. Because imaging plays a critical role in evaluating essentially all liver mass lesions, it is imperative that they be managed in close association with an experienced imaging expert. Recommendations 1. Liver biopsy should be considered in patients in whom diagnosis is in question, and when knowledge of a specific diagnosis is likely to alter the management plan (Class I, Level B). 2. Liver histology is an important adjunct in the management of patients with known liver disease, particularly in situations where (prognostic) information about fibrosis stage may guide subsequent treatment; the decision to perform liver biopsy in these situations should be closely tied to consideration of the risks and benefits of the procedure (Class I, Level B). The general approach to liver biopsy has changed substantially over the past 10–20 years. Currently, liver biopsy is typically undertaken on an outpatient or “same day” basis. Most often, the patient will have been seen in the clinic or office within the preceding month where a discussion about the indications for, benefits, and risks of liver biopsy will have occurred. Because it is well-appreciated that many patients undergoing liver biopsy experience significant anxiety about the procedure, the following practical points should also be discussed before the procedure: (1) by whom and where the biopsy will be performed, (2) whether sedation of any sort may be taken prior to the procedure, or will be available immediately beforehand, (3) what degree of pain may be anticipated during and after the procedure, and the measures available that might help minimize and/or attenuate it, (4) when the patient may return to their usual level of activity, and to work outside the home if applicable, and (5) when the result will be known, and by what means this information will be communicated to the patient. Being clear and precise about these pragmatic issues are important to facilitate performance of the procedure and instill in the patient a sense of confidence. Written informed consent, including risks, benefits, and alternatives, should be obtained prior to liver biopsy. Recommendations 3. Prior to performance of liver biopsy, patients should be educated about their liver disease and about investigations other than liver biopsy (if any) that may also provide diagnostic and prognostic information (Class I, Level C). 4. Prior to performance of liver biopsy, patients must be carefully informed about the procedure itself including alternatives (as above), risks, benefits, and limitations; written informed consent should be obtained (Class I, Level C). Common practice includes measurement of the complete blood count, including platelet count, prothrombin time (PT)/international normalized ratio (INR), in some institutions the activated partial thromboplastin time, and/or cutaneous bleeding time at a suitable juncture prior to the biopsy. Some experts recommend having a specimen of blood typed, so that blood could be made available at short notice in case of bleeding. Patients with previously documented abnormalities in laboratory tests may require these to be repeated closer to the time of biopsy; the time frame will vary depending on the specific clinical scenario and local policies. However, as highlighted below, the utility of these tests in predicting bleeding risk is uncertain and generally not supported by the available literature.88-91 Moreover, the prevalence of more complex hemostatic defects in patients undergoing biopsy, such as hyperfibrinolysis, which are undetectable by conventional tests, is unknown, although some 10%–15% of hospitalized patients with cirrhosis appear to have this particular problem.92-94 Hyperfibrinolysis should be suspected when there is late (hours) postprocedure bleeding, consistent with initial clot formation and premature clot dissolution thereafter. Additional studies are needed to assess the preprocedure utility of more global measures of hemostasis such as thromboelastography; this test assesses indices of hyperfibrinolysis and platelet function. Additionally, imaging reports should be reviewed to ensure that (1) no focal lesion exists in the right hepatic lobe, e.g., hemangioma; and (2) that biliary dilation is not present. Either of these conditions might give rise to an otherwise unsuspected (and avoidable) complication. Experts vary in their preference as to whether patients should be fasting prior to biopsy, and data to shed light on the best approach are not available. There is anecdotal evidence that a light snack 2–4 hours before transthoracic liver biopsy may help avoid a vasovagal response during or shortly after the procedure. Some experts ask patients to consume a light fatty breakfast so as to encourage gallbladder contraction (and thus presumably reduce the likelihood of gallbladder perforation). On the other hand, others have raised the possibility that postprandial hyperemia may increase portal blood flow, and could theoretically increase the risk of bleeding. Further, the nonfasting state may create difficulties in the event of a major complication. Nearly all recommendations regarding periprocedure restrictions lack definitive evidence because few recommendations (other than patient positioning immediately after biopsy; see below) have actually undergone comparative study. However, a numbe