What is the role of endoscopic ultrasound (EUS) in the workup of biliary obstruction?

Updated: Oct 16, 2019
  • Author: Jennifer Lynn Bonheur, MD; Chief Editor: Vinay Kumar Kapoor, MBBS, MS, FRCS, FAMS  more...
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Answer

EUS combines endoscopy and US to provide remarkably detailed images of the pancreas and biliary tree. It uses higher-frequency ultrasonic waves compared to traditional US (3.5 MHz vs 20 MHz) and allows diagnostic tissue sampling via EUS-guided fine-needle aspiration (EUS-FNA). [11]

Although endoscopic retrograde cholangiography is the procedure of choice for biliary decompression in obstructive jaundice, biliary access is not always achievable, in which case, interventional endoscopic ultrasound-guided cholangiography (IEUC) may offer an alternative to percutaneous transhepatic cholangiography (PTC). Maranki et al reported their 5-year experience with IEUC in patients who had unsuccessful treatment with ERCP. [12] The investigators used either a transgastric-transhepatic or transenteric-transcholedochal approach to the targeted biliary duct, then advanced a stent over the wire into the biliary tree. [12]

Of the 49 patients who underwent IEUC, the cause of biliary obstruction was a malignancy in 35, whereas 14 had a benign etiology. [12] Forty-one of the 49 patients (84%) had successful overall therapy with IEUC, with an overall complication rate of 16%. Resolution of obstruction had an 83% success rate (n = 29). The transenteric-transcholedochal approach was used in 14 patients, with successful biliary decompress in 86% (n = 12). [12] No procedure-related deaths were reported. Thus, overall, the intrahepatic approach was successful in 73% (29/40) of cases, and the extrahepatic approach was successful in 78% (7/9) cases. [12]

An international multicenter retrospective analysis found comparable short-term outcomes between EUS-guided biliary drainage and ERCP in 208 patients with&malignant distal common bile duct obstruction who required the placement of self-expandable stents. [13] Ninety-seven of 104 patients (94.23%) who underwent EUS-guided biliary drainage and 98 of 104 patients (93.26%) who underwent ERCP had successful stent placement (P = 1.00); each group had an 8.65% frequency of adverse events, and the mean procedural times were similar (35.95 mins vs 30.10 mins, respectively; P = 0.05). However, the rates of postprocedure pancreatitis were higher in the ERCP group (4.8% vs 0%, P = 0.059). [13]

EUS has been reported to have up to a 98% diagnostic accuracy in patients with obstructive jaundice. This makes ERCP unnecessary in patients who are found to not have extrahepatic obstruction. In addition, those patients who may require operative biliary drainage are reliably identified and similarly need not undergo ERCP for further evaluation. [14]

EUS provides highly detailed imaging of the pancreas. The sensitivity of EUS for the identification of focal mass lesions has been reported to be superior to that of CT scanning, both traditional and spiral, particularly for tumors smaller than 3 cm in diameter.

Compared to MRCP for the diagnosis of biliary stricture, EUS has been reported to be more specific (100% vs 76%) and to have a much greater positive predictive value (100% vs 25%), although the two have equal sensitivity (67%).

Neither transabdominal US nor CT scanning can help reliably exclude the presence of choledocholithiasis. ERCP is highly accurate for this diagnosis but, because of the associated risk of pancreatitis, is generally reserved for patients with known common duct stones. EUS has been reported to have sensitivity approximately equal to both ERCP and MRCP for the detection of common duct stones, with minimal risks directly associated with the procedure.

EUS is more portable than ERCP or MRCP and is useful for patients in the intensive care unit. EUS (if performed in the fluoroscopy suite) can be followed immediately by therapeutic ERCP, which saves time.

The positive yield of EUS-FNA for cytology in patients with malignant obstruction has been reported to be as high as 96%.


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