Practiced since the late 19th century, liver biopsy remains the criterion standard in the evaluation of the etiology and extent of disease of the liver. Paul Ehrlich performed a percutaneous liver biopsy in Germany in 1883. In the late 1950s, Menghini developed a 1-second aspiration technique, which led to wider use of the procedure and broadened its applications.
Since Menghini, the evolution of liver biopsy has been extensive. At present, percutaneous biopsies are performed primarily by specialists in gastroenterology/hepatology or by radiologists.
A variety of approaches may be utilized for obtaining a liver tissue specimen. These include a blind percutaneous approach after percussion of the chest wall, biopsy under the guidance of ultrasonography or computed tomography (CT), intravascular tissue sampling via the hepatic vein, and intra-abdominal biopsy at laparoscopy or laparotomy.  An endoscopic ultrasound-guided approach has been described. 
The choice of one technique over another is based on availability, personal preference, and the clinical situation. Likewise, various needles are available for use, depending on the approach and on physician experience.
Some controversy remains as to what constitutes an adequate liver biopsy sample for accurate evaluation. In general, a sample that is 1.5 cm long and 1.2-2 mm in diameter and contains at least six to eight portal triads is considered adequate. This represents approximately 0.002% of the adult liver. Some hepatologists have advocated the use of 4-cm tissue samples to minimize sampling error, whereas others have found samples of 1 cm to produce minimal interobserver variability. 
Although liver biopsy is generally safe and is currently considered the criterion standard for the evaluation of hepatic inflammation and fibrosis, sampling error, rare complications, and, occasionally, significant patient anxiety do occur. These factors have led to keen interest in the development of noninvasive tests for hepatic fibrosis, [4, 5] some of which are now commercially available in the United States.
Although these tests hold promise for reducing the need for liver biopsy, most hepatologists feel that their clinical usefulness is limited at this time. The available tests appear to perform well at the extreme ends of the spectrum of chronic liver disease, but results vary considerably in the intermediate stages of disease frequently seen in clinical practice. Lack of validation of these tests in the community settings where they would most likely be used is also a potential shortcoming of the current testing methods.
Liver biopsy, in combination with history and physical examination data, is a powerful clinical tool for diagnosing and treating liver disease. Indications for obtaining a biopsy specimen, divided according to the type of clinical question framed, are as follows:
Evaluation of abnormal hepatic laboratory test results
Confirmation of diagnosis and prognostication
Suspected hepatic neoplasm
Diagnosis of cholestatic liver disease
Evaluation of infiltrative or granulomatous disease
Following a case of liver transplantation to evaluate and manage rejection
To evaluate unexplained jaundice or suspected drug reactions
The biopsy specimen may be used to identify or exclude possible etiologies for physical or laboratory abnormalities. Although various disease states may present similarly, diagnostic histologic patterns exist when used in the context of clinical presentation. For example, infiltration of the hepatic parenchyma by fat may exist in diseases due to alcohol abuse, hepatitis C, diabetes, obesity, or combinations thereof. For each disease state, histologic clues exist that distinguish one from the other. [6, 7, 8]
Liver biopsy plays little role in the determination of the organism responsible for systemic infection because blood cultures generally are revealing. The notable exceptions are intrahepatic tuberculosis and Mycobacterium avium complex (MAC).
Another indication for biopsy is the determination of the extent of histologic change present in a biopsy specimen. This involves scoring systems for the degrees of inflammation and fibrosis noted by the pathologist. Many systems exist for describing the microscopic findings, ranging from simplistic to complex. The majority of scoring systems report the degree of inflammation as the grade of the disease and the amount of fibrosis as the stage. An example here would be the finding of moderate inflammation (grade 3) in a specimen from a cirrhotic (stage 4) liver.
The third set of indications is the monitoring of the progression of disease or of treatment efficacy. For example, liver biopsy specimens frequently are used to evaluate and treat rejection following liver transplantation. Repeated biopsies are used less frequently to monitor progression of diseases such as primary biliary cirrhosis, chronic hepatitis C,  or alcoholic liver disease.
Regardless of the indication for the biopsy, identifying which information the procedure is anticipated to yield is important.
Contraindications to percutaneous liver biopsy are relatively few, but identifying contraindications is important to avoid the major complications associated with the procedure. Contraindications to liver biopsy include the following: