Endoscopic Ultrasound Guided Liver Biopsy Using a 19-gauge Fine Needle Biopsy Needle

Liver biopsy (LB) has historically been performed by percutaneous route without image guidance (blind biopsy). However, in the last several years there has been more reliance on image guidance ultrasound-guided (USG) or computed tomography (CT) to direct the needle into the liver with the hope of limiting complications 1. Other ways of performing liver biopsy are transjugular fluoroscopy guided approach when percutaneous route is deemed not safe because of coagulopathy or ascites 2. Surgical LB (either laparoscopic or open) is yet another way of obtaining liver tissue.

Endoscopic ultrasound guided liver biopsy (EUS-LB) is proposed as a newer method that may offer several potential advantages over existing techniques for attaining liver tissue 3-8. It can be performed in an outpatient setting and offers the comfort of sedation and analgesia. EUS-LB is a technically reproducible approach regardless of body habitus, because the needle only requires traversing the gastric or duodenal wall to reach hepatic parenchyma. It also offers the benefit of a comprehensive evaluation of the GI tract, including screening or surveying for esophageal varices. EUS provides high resolution images of left lobe of the liver and a good portion of the right lobe of the liver. This coupled with Doppler capability the biopsy needle can be safely directed into the liver for sampling under real time image guidance. Intervening structures such as pleura, bowel loops and gallbladder can be easily seen by EUS and thus avoided that further decreases the risk of adverse events. It has been recognized that sampling error can lead to diagnostic inaccuracy of a biopsy from a single site 9. As compared to USG or CT scan the EUS allows easy and safe biopsy of both left and right lobes of the liver during same setting, potentially addressing concerns about sampling error.

The cost of the endoscopic procedure is the main expense of EUS-LB. Thus, this approach is best used for patients requiring EUS for evaluation of elevated liver tests. If no obstructive lesion is identified by EUS that will require ERCP then it would cost-effective to perform EUS LB during the same setting without much additional time and risks. This approach can spare the patient the additional discomfort and expense of a second dedicated LB procedure by any of the other available techniques (percutaneous, transjugular etc.). In such setting the equipment costs for the EUS-LB will mainly include only the Fine Needle Biopsy (FNB) needle, which is similar in expense to the cost of needles for the transjugular or percutaneous approach.

The traditionally used transcutaneous LB needle is 16 gauge (G) while largest EUS biopsy needle is 19 gauge. The smaller size of the needle is expected to decrease the complications rate (mainly pain and bleeding) even further. Many studies using a 19 gauge Tru-cut biopsy or Fine Needle Aspiration (FNA) needle to acquire liver tissue have obtained specimens adequate for histologic diagnosis 3-7 but there has been a wide range of specimen adequacy (19-100%). Overall, there is limited data comparing the diagnostic yield of different FNA and FNB needles.

In a recently reported systematic review and meta-analysis 10, the insufficient specimen rate with 19 gauge FNA needle was 4% compared with 20% with 19 gauge core needles, with a p value of 0.03. FNA needle demonstrated a non-significant trend toward better diagnostic results (95.8% vs 92.7%, p=0.59) and a non-significant trend toward lower rates of adverse-events (0.9% vs 2.7%, p=0.28) when compared with the core biopsy needles. The 19-gauge FNA needle used was EchoTip (Wilson Cook Medical) in one study 6 and Expect (Boston Scientific) in rest two studies 8,11. The various types of core needles used were Quick-Core 12, Pro-Core 12, SharkCore 13,14, and the Acquire needle 15.