The role of intraductal ultrasound in endoscopic biliary brushing for sampling in patients with malignant biliary strictures: a bicentric retrospective study

Abstract

Background Endoscopic biliary brushing is the first line modality for sampling in patients with indeterminate biliary stricture (BS); however, its sensitivity is limited. Endoscopic intraductal ultrasound (IDUS) is also a useful approach for the diagnosis of biliary malignancies. However, whether IDUS can guide the sampling by biliary brushing has not been reported.

Methods We retrospectively analyzed patients who underwent endoscopic retrograde cholangiopancreatography for BS in 2 tertiary care hospitals and assessed the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of IDUS and brush cytology.

Results The study involved 530 patients with BS, including 333 in the IDUS group and 197 in the non-IDUS group. Both groups exhibited similar baseline characteristics. The diagnostic ability of IDUS imaging was as follows: sensitivity 70.7%, specificity 82.4%, PPV 81.5%, NPV 72.0%, and accuracy 76.3%. Brush cytology alone demonstrated an overall sensitivity of 45.2%, with specificity 98.2%, PPV 97.2%, NPV 56.0%, and accuracy 67.2%. The sensitivity was similar in patients with or without IDUS, whereas it was significantly higher in patients with biliary mucosal invasion indicated by IDUS (55.1% vs. 30.3%, P=0.003).

Conclusion Although IDUS cannot improve the detection rate of biliary brushing for malignancy, it helps identify patients with malignant BS to be sampled more easily by brushing.

Keywords Endoscopic retrograde cholangiopancreatography, biliary stricture, intraductal ultrasound, brush cytology

Ann Gastroenterol 2025; 38 (2): 208-213