**2. Post-transplant liver biopsy techniques**

Liver biopsies can be performed with various techniques, including a percutaneous ap‐ proach (with marking by percussion/palpation, marking by ultrasound (US), or under realtime US or computed tomography (CT) guidance), a transjugular approach, or a surgical/ laparoscopic approach. Although percutaneous liver biopsies on non-transplant patients can be done without the use of imaging, it is recommended that patients who have undergone any abdominal surgery (including liver transplantation) undergo biopsies aided by the use of US to avoid vascular or other structures [1]. While US marking followed by biopsy is suf‐ ficient in most post-transplant patients, in certain situations (such as split-liver recipients), biopsy under real-time US or CT guidance is preferred to avoid encountering intervening bowel loops. While specimens at least 1.5cm in length and containing at least 6-8 portal tri‐ ads are considered adequate for the diagnosis of chronic liver disease [2,3], some advocate a minimum length of 2.0 cm and at least 11 complete portal tracts for accurate grading and staging of liver disease [4].

© 2012 Limaye et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Percutaneous liver biopsy can be performed rapidly and safely in an outpatient setting with the appropriate monitoring equipment and staff availability [5]. After discharge, patients are typically instructed to avoid strenuous physical activity or driving for 24-48 hours, and are asked to contact the clinical provider in the event of concerning symptoms. In our institu‐ tion, a review of over 3,000 liver biopsies (including liver transplant patients) demonstrated that the majority of complications were discovered within the first hour after percutaneous liver biopsy, and that shortening the recovery time to 1-2 hours did not impact the frequen‐ cy of complications [6].

plications between 0.2% and 1.8% [13]. While early studies suggested an increased risk of post-biopsy sepsis in patients with Roux-en-Y choledochojejunostomy, subsequent studies

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617 191

Abnormalities in liver enzyme levels are often encountered in liver transplant patients, and can represent hepatocellular injury (reflected by the transaminases), biliary injury [reflected by alkaline phosphatase or gamma-glutamyl transferase (GGT)], or hepatic synthetic dys‐ function (reflected by the albumin or by coagulation abnormalities). While the use of serum blood tests (such as viral or autoimmune serologies) and imaging techniques (such as ultra‐ sound with Doppler, angiography, and magnetic resonance cholangiography) can be useful to determine the etiology of abnormal liver enzymes, liver biopsy is often necessary for a

The differential diagnosis of liver enzyme abnormalities varies with the amount of time which has passed since liver transplant. In the normal post-transplant course, liver enzymes typically rise immediately following transplant and become normal or near-normal within 3-5 days. If the enzymes fail to improve or normalize but soon rise again, it is likely that an early complication has occurred (Table 1). In the very early post-transplant period (within the first week), liver enzyme abnormalities can be related to primary graft nonfunction (PNF) or dysfunction, hepatic arterial insufficiency, small for size syndrome (SFSS), or portal

PNF and primary graft dysfunction are associated with prolonged ischemia time [15], and it is likely that preservation and reperfusion injury play a role. PNF is heralded by a precipi‐ tous rise in hepatic transaminases in the second or third postoperative day accompanied by signs of hepatic failure (encephalopathy and coagulopathy). Once hepatic artery thrombosis (HAT) has been ruled out by imaging, a liver biopsy confirms the diagnosis. Biopsies in this setting typically show centrilobular hepatocyte dropout due to hepatocellular necrosis, with

The clinical presentation of HAT is quite similar to that of PNF, with a dramatic increase in hepatic transaminases and bilirubin in the very early post-transplant period. A liver biopsy is typically not required, as the diagnosis can usually be confirmed with angiography. When

compensatory zone 2 hepatocyte proliferation and bile ductular proliferation [16].

show that the risk is similar to patients with a duct-to-duct anastomosis [14].

**4. Post-transplant liver enzyme abnormalities**

**5. Early post-transplant liver enzyme abnormalities**

definitive diagnosis.

venous thrombosis (PVT).

**5.1. Primary graft dysfunction**

**5.2. Hepatic artery thrombosis**

Percutaneous liver biopsy can be performed with suction needles (such as Jamshidi needle or Menghini needle), cutting needles (such as the Tru-Cut needle), or spring-loaded needle "guns". Specimens adequate for diagnosis, grading, and staging can usually be obtained by all of the biopsy needles used in current practice.

In patients with severe/uncorrectable coagulopathy, thrombocytopenia (typically platelet count < 50,000/mm3 ), large ascites, morbid obesity, or an inability to cooperate, a transjugu‐ lar liver biopsy (TJLB) is typically recommended [7]. In addition, TJLB is useful in patients for whom wedged hepatic venous pressure gradient (HVPG) measurement would be clini‐ cally useful. Miraglia et al reported on the safety of TJLB in liver transplant patients, with only one complication in 183 biopsies (0.5%) [8].

TJLB is typically performed with the use of automated needle systems, such as the Quick-Core needle and the Flexcore needle. It has been established that these automated needle systems often require multiple passes, and usually collect smaller core samples than those obtained by percutaneous liver biopsy [9]. Despite this fact, specimens ob‐ tained via TJLB are adequate for diagnosis, staging, and grading liver disease in greater than 90% of cases [10,11].

Surgical liver biopsies (either open liver biopsy or laparoscopic liver biopsy) are typically performed when patients require a surgical procedure for another indication. In liver trans‐ plant patients, this often involves repair of postoperative hernias. Biopsies in this setting can be performed with either automated needle systems or with a wedge resection, and the pro‐ cedure provides the advantage of direct visualization of the liver and the ability to immedi‐ ately diagnose and treat any bleeding which occurs.
