Linear endoscopic ultrasound for clinically suspected bile duct stones : Journal of the Chinese Medical Association

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Original Article

Linear endoscopic ultrasound for clinically suspected bile duct stones

Lin, Lien-Fu*; Huang, Pi-Teh

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Journal of the Chinese Medical Association: June 2012 - Volume 75 - Issue 6 - p 251-254
doi: 10.1016/j.jcma.2012.04.006


    1. Introduction

    Conventional endoscopic retrograde cholangiopancreatography (ERCP) is supposed to be the gold standard for detection of common bile duct stones (CBDS) but it can yield negative results in 38–80% of cases with unconfirmed CBDS.1,2 Furthermore, ERCP carries a risk of pancreatitis of up to 2%. EUS is a less invasive imaging modality for evaluation of CBDS with accuracy comparable to that of ERCP.3 Patients classified as high risk of suspected CBDS were found to have stones in only two-thirds of cases.4,5 It is reasonable to perform EUS in all clinically suspected unconfirmed cases of CBDS. Most of the reports in the literature focused on radial EUS, with few reports involving linear EUS for CBDS.6 We report our experience of linear EUS for clinically suspected CBDS where stones were not detected by prior transabdominal ultrasonography (TAU) or computed tomography (CT) imaging.

    2. Methods

    This is a retrospective analysis of prospectively collected data. From December 2009 to June 2011, a total of 30 patients with suspected CBDS were enrolled for a linear EUS study. The inclusion criteria were: (1) acute upper abdominal pain and abnormal liver function test (with or without fever, with gall bladder (GB) in situ or post-cholecystectomy, with or without biliary dilation); and (2) CBDS not detected by TAU or CT. The exclusion criteria were: (1) a linear EUS endoscope could not be inserted into the duodenum; and (2) Billroth II gastrectomy. Negative CBDS on linear EUS was defined as no CBDS found on linear EUS, relief of biliary colic, improvement in liver function test (LFT), and a follow-up period of at least 3 months. An abnormal LFT was defined as elevation of aspartate transaminase, alanine transaminase, bilirubin, and r-glutamine transpeptidase (rGT) above normal upper limits. Suspected CBDS was classified as high or intermediate risk according to standard guidelines,7 but without CBDS detected in TAU or CT images. High-risk predictors according to the guidelines include CBDS observed by TAU or clinical ascending cholangitis or bilirubin >4 mg/dL or both dilated CBD on TAU and bilirubin of 1.8–4 mg/dL.7 Patients with abnormal LFT other than bilirubin, or >55 years of age or with clinical gallstone pancreatitis were classified as intermediate risk. After written informed consent was obtained, conscious sedation (demerol, midazolam) was administered to the patient and EKG, blood pressure, and pulse oximetry were monitored during linear EUS (GF-UCT2000, EUC2000 unit, Olympus, Tokyo, Japan) of the stomach, duodenal bulb, and descending duodenum (Fig. 1A–C). In cases with positive CBDS, ERCP or endoscopic sphincterotomy (EST) was performed (Fig. 2A–C). For patients who tested negative for CBDS on linear EUS, LFT was performed on the second and fourth days, and then followed for at least for 3 months (at OPD or by phone).

    Fig. 1:
    Common bile duct stones detected by linear endoscopic ultrasound in (A) the stomach, (B) the duodenal bulb and (C) the descending duodenum.
    Fig. 2:
    (A) Common bile duct stone detected in the stomach and confirmed by (B) endoscopic sphincterotomy and (C) stone extraction.

    3. Results

    The results are shown in Chart 1. There were 17 male and 13 female patients with a mean age of 53 (±17.6) years. Sixteen cases were classified as high risk for CBDS (3 had mild intra-hepatic duct dilation) and 14 as intermediate risk. Linear EUS detected CBDS in 12 cases (10 in the high-risk group, 2 in the intermediate-risk group). EST was performed in 10 cases and one case underwent surgery because of multiple large CBDS. The false-positive CBDS was a case of GB neck cancer with invasion of the common hepatic duct (CHD). The echogenic lesion was mistaken for a stone (Fig. 3A), but ERC revealed a malignant CHD stricture (Fig. 3B), CT showed low density in the GB region (Fig. 3C), and histological analysis using endoscopic retrograde brush cytology and a transpapillary biopsy revealed adenocarcinoma (Fig. 3D–F). Together, these findings led to a pre-operative diagnosis of GB cancer with invasion of the CHD. Among 18 cases of negative EUS findings for CBDS, one had an intra-operative cholangiogram performed during laparoscopic cholecystectomy. The median follow-up duration for the remaining 17 cases was 9 months (range 3–12). In these 17 cases, 15 had no biliary colic, no biliary dilation, and normal LFT during the follow-up period. One had pancreatitis due to alcohol with no CBDS observed on a second EUS examination, and the remaining case had mild elevation of rGT due to consumption of herbs. The overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 100%, 94.7%, 91.7%, 100%, and 96.7%, respectively. CBDS was positive in 56% (9/16) of the high-risk patients, with one false-positive case, and 14.3% (2/14) of the intermediate-risk patients.

    Fig. 3:
    (A) Echogenic lesion mistaken for a common bile duct stone. (B) Malignant common hepatic duct stricture on endoscopic retrograde cholangiography (ERCP). (C) Low-density lesion of the gall bladder demonstrated by computed tomography. (D) Endoscopic retrograde brushing cytology during ERCP. (E) Endoscopic transpapillary biopsy during ERCP. (F) A moderately differentiated adenocarcinoma was found.

    4. Discussion

    EUS is relatively non-invasive compared with ERCP but has high accuracy in predicting CBDS. In a meta-analysis of radial EUS, the overall pooled sensitivity was 0.94 (95% CI 0.93–0.96) and the specificity was 0.95 (95% CI 0.94–0.96), with an area under the curve of 0.98.3 However, very few linear EUS studies to assess CBDS have been reported.8–10 In our series, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for CBDS detection were 100%, 94.7%, 91.7%, 100%, and 96.7%, respectively. We had one false-positive case mistaken for CBDS, which was later identified as GB cancer with invasion of the common hepatic duct by ERCP and trans-papillary brushing cytology and biopsy. A review of the images indicates that the echogenic lesion (Fig. 3A) could be sludge or a tumor in the bile duct. Lachter et al reported four false positives out of 50 cases using linear EUS,8 but higher specificity of 93% was reported by Kohut et al.9

    We found a CBDS-positive rate of 56% in the high-risk group and 14.3% in the intermediate-risk group. According to the literature, the CBDS-positive rate ranges from 10% to 50% in intermediate-risk groups and is greater than 50% in high-risk groups.7 We saved 44% of our high-risk and 85.7% of our intermediate-risk patients an ERCP procedure. According to guidelines,7 ERCP is recommended for high-risk patients, but CBDS observed by TAU is included in the criteria for high-risk patients. We excluded patients with CBDS observed by TAU or CT from our high-risk group, and therefore EUS was worthwhile for the high-risk group in our series.

    We did not use ERCP as a confirmation test for negative CBDS on linear EUS. Kohut et al did not use ERCP either, but their clinical follow-up for negative CBDS on linear EUS was of longer duration.10 The limitation of our study is the shorter follow-up period in some cases of negative CBDS, although the median follow-up duration was 9 months.

    In conclusion, linear EUS should be considered sensitive for the detection of CBDS and can be useful in intermediate-and high-risk patients when CBDS is not detected by prior TAU or abdominal CT imaging.


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    common bile duct stone; endoscopic retrograde cholangiogram; linear endoscopic ultrasound

    © 2012 by Lippincott Williams & Wilkins, Inc.