Historically, the role of endoscopy in hepatology has been limited to intraluminal and bile duct interventions, primarily for the management of varices and biliary strictures. Recently, endoscopic ultrasound (EUS) has broadened the range of endoscopic treatment by enabling transluminal access to the liver parenchyma and associated vasculature. In this review, we will address recent advances in the expanding field of endohepatology.
Endoscopic-ultrasound guided liver biopsy
Liver biopsies are a critical tool in the diagnostic evaluation and management of patients with liver disease. Conventional approaches for obtaining liver tissue have been most commonly through the percutaneous or vascular approaches. In 2007, the first EUS-guided liver biopsy (EUS-LB) was described.1 EUS-LB is performed by advancing a line-array echoendoscope to the duodenal bulb to access the right lobe of the liver or proximal stomach to sample the left lobe. Doppler is first used to identify a pathway with few intervening vessels. Then a 19G or 20G needle is passed and slowly withdrawn to capture tissue (Figure 1). Careful evaluation with Doppler ultrasound to evaluate for bleeding is recommended after EUS-LB and if persistent, a small amount of clot may be reinjected as a blood or “Chang” patch akin to technique to control oozing postlumbar puncture.2
While large prospective studies are needed to compare the methods, it appears that specimen adequacy acquired via EUS-LB are comparable to percutaneous and transjugular approaches.3-5 Utilization of specific needle types and suction may optimize samples. Namely, 19G needles may provide better samples than smaller sizes and contemporary fine-needle biopsy needles with Franseen tips are superior to conventional spring-loaded cutting needles and fork tip needles.6-8 The use of dry suction has been shown to increase the yield of tissue, but at the expense of increased bloodiness. Wet suction, which involves the presence of fluid, rather than air, in the needle lumen to lubricate and improve transmission of negative pressure to the needle tip, is the preferred technique for EUS-LB given improvement in the likelihood of intact liver biopsy cores and increased specimen adequacy.9
There are several advantages to EUS-LB (Table 1). When compared with percutaneous liver biopsy (PC-LB) and transjugular liver biopsy (TJ-LB), EUS-LB is uniquely able to access both liver lobes in a single setting, which minimizes sampling error.3 EUS-LB may also have an advantage in sampling focal liver lesions given the close proximity of the transducer to the liver.10 Another advantage over PC-LB is that EUS-LB can be performed in patients with a large body habitus. Additionally, EUS-LB is better tolerated than PC-LB, with less postprocedure pain and shorter postprocedure monitoring time.4,5
Rates of adverse events appear to be similar between the three methods. Similar to PC-LB, EUS-LB requires capsular puncture, which can lead to intraperitoneal hemorrhage. Therefore, TJ-LB is preferred in patients with significant coagulopathy. While small ascites is not an absolute contraindication for EUS-LB, large ascites can obscure a safe window from the proximal stomach or duodenum to the liver, and thus TJLB is also preferred in these patients.11 Given its relative novelty and logistic challenges, other disadvantages of EUS-LB include limited provider availability and increased cost, especially compared with PC-LB. The most significant limitation is that it requires moderate or deep sedation, as opposed to local anesthetics. However, if there is another indication for endoscopy (that is, variceal screening), then “one-stop shop” procedures including EUS-LB may be more convenient and cost-effective than traditional methods. Nevertheless, rigorous comparative studies are needed.