Endoscopic Ultrasound-Guided Liver Biopsy
Enad Dawod, MD
Jose M. Nieto, DO, AGAF, FACP, FACG, FASGE
Liver pathology falls on a very wide spectrum, which makes it difficult to distinguish specific pathologies based on clinical presentation, serologic markers, or imaging alone. Liver biopsy (LB) plays a vital role in liver disease management through establishing a specific underlying etiology, determining the severity of liver damage, determining prognosis, and preventing missing fibrosis or cirrhosis that would be otherwise missed on laboratory or imaging evaluation. The need for LB also varies by the etiology of liver disease as the emergence of noninvasive markers for hepatitis C and fibrosis decreased the need for histological evaluation. However, with other etiologies such as autoimmune hepatitis and nonalcoholic hepatosteatosis, the need for liver sampling still persists.1,2,3 More importantly, LB has a role in altering treatment in many patients based on histopathological findings.4
Percutaneous liver biopsy (PC-LB) is the conventional and most commonly used method for liver sampling. This method, however, does come with its own set of limitations, high cost, and procedure-related adverse events, which makes PC-LB an unfeasible method of monitoring patients in the long run.5 PC-LB is limited by the absence of mass visualization, high rates of sampling error, and failure to obtain samples adequate enough for histological evaluation.6 The high rate of procedural-related adverse events is attributed to the invasive nature of the procedure and they include severe pain, intraperitoneal and subcapsular hemorrhage, unintentional sampling of adjacent organs, pneumothorax, marked hypotension, and discomfort to the patient.7,8 The rate of adverse events in the PC method may be up to 60% in the first 2 hours after the procedure.4,9 When there are contraindications for the PC method, such as ascites or coagulopathy, a transjugular fluoroscopy-guided approach is used.10
Endoscopic ultrasound (EUS)-guided LB is an emerging approach that provides an alternative to the conventional method. The EUS-guided approach could be utilized during the evaluation of both focal and parenchymal liver disease. Several studies have been published that have demonstrated safety and efficacy of EUS in liver sampling in addition to its ability to obtain tissue adequate for establishing histopathological diagnosis.8,11,12,13 EUS-LB could decrease the time to diagnosis and help avoid the need for a second procedure to reach a diagnosis when an EUS is performed in the evaluation of abnormal imaging, unexplained liver tests, or other pancreatobiliary disease.
TECHNIQUE
EUS-FNA and EUS-FNB for Focal Liver Lesions
1. EUS examinations are usually performed in the left lateral decubitus position with a linear echoendoscope.
2. All patients undergo moderate/deep sedation, which in the United States is administered by a staff anesthesiologist or a registered nurse.
3. The cytology aspiration is performed using an EUS-FNA needle and for tissue acquisition, an EUS-FNB needle (25G and 22G are more commonly used, than 19G FNA/FNB needles for focal lesions).
4. The left lobe of the liver is accessed with the echoendoscope in the proximal stomach, distal to the gastroesophageal junction. The right lobe of the liver is accessed with the echoendoscope positioned in the duodenal bulb and torqued counterclockwise, beyond the view of the portal vein and the gallbladder (if present).
5. Doppler is used to identify an area of liver parenchyma in the expected trajectory of the needle that is clear of blood vessels or bile ducts.
6. After initial puncture is made into the lesion or liver parenchyma, 7 to 14 actuations (back-and-forth motions of the needle) are made per pass and a “fanning” technique is used to maximize tissue sampling. This technique involves changing the trajectory of the needle with each back-and-forth movement. Negative pressure can be applied using suction with a 10 to 20 mL syringe or the stylet can be slowly withdrawn from the needle after it enters the target lesion. Suction is released by closing the syringe lock, and the needle could then be finally removed. Aspiration specimens are expelled onto glass slides by reinserting the stylet. The aspiration could be repeated until enough specimens are obtained, as deemed adequate by gross inspection (Fig. 31.1).
FIG. 31.1 Live view of parenchymal tissue obtained via EUS.
7. When on-site evaluation is performed, the specimen samples are smeared on glass slides for cytological examination, fixed in 95% ethanol, and stained with hematoxylin and eosin stain (Fig. 31.2).
EUS for Parenchymal Disease
The use of EUS is more established in focal liver lesions than in parenchymal liver disease. However, the use of a newer flexible core needles have made it possible to obtain parenchymal cores.11,15 Quick-Core (Cook Medical Inc, Bloomington, IN) was the first FNB needle designed for obtaining core biopsy specimens by means of a spring-loaded tru-cut mechanism.16 EUS-modified liver biopsy sampling (EUS-MLB) for obtaining a parenchymal core uses a novel 19-gauge needle (Sharkcore; Medtronic, Sunnyvale, CA) or the Acquire (Franseen tip Needle, Boston, MA) with a modified 1-pass 1-actuation wet suction technique. The 19-gauge needle has a modified tip design containing
six cutting edge surfaces and an opposing bevel to catch tissue as it is sheared off.11 The introduction of other biopsy needles into the market place is expected.
six cutting edge surfaces and an opposing bevel to catch tissue as it is sheared off.11 The introduction of other biopsy needles into the market place is expected.
 FIG. 31.2 Histological view of the parenchymal tissue sampled via EUS. |
EUS-Modified Liver Biopsy Sampling
1. All patients undergo moderate/deep sedation, which in the United States is administered by a staff anesthesiologist or a registered nurse. A complete EUS examination for the primary procedure indication is performed.
2. Echoendoscopy is performed using a standard linear-array echoendoscope. In addition, complete EUS surveillance of the visualized liver and upper abdominal region was done to ensure the absence of varices or tumor.
3. EUS-MLB under real-time US guidance is performed by using a 19-gauge needle (Sharkcore; Medtronic) or (Acquire, Boston Scientific). Although FNB needles are used, 19G FNA needles can also be used.
4. The needle is primed with saline solution, and maximal suction is applied via a syringe after 7 cm of the needle had entered the liver under direct US guidance, being careful to avoid large vessels using Doppler.
5. A rapid-puncture one 7-cm actuation technique is used to sample each lobe for a total of 1 actuation per lobe. The 8-cm 19-gauge core needle is then passed into the liver and approximately 1 cm passed through stomach or duodenal wall. The other 7 cm was passed into the liver parenchyma. The left lobe is accessed by the transgastric route and the right lobe by the transduodenal route.
6. Wet suction is used to indicate tissue acquisition into the bore of the needle by displacing the saline solution into the syringe; this notifies the endoscopist to turn off the suction11(Figs. 31.1, 31.2, 31.3 and 31.4).
7. Some endoscopists employ a slow-pull capillary suction technique and multiple passes for FNB as per solid lesions.15Related posts:
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