Endoscopy 2013; 45(03): 227
DOI: 10.1055/s-0032-1326012
Letters to the editor
© Georg Thieme Verlag KG Stuttgart · New York

The utility of duodenal endosonography examination in the diagnostic work-up of primary sclerosing cholangitis

Y. Ustundag
,
M. Eloubeidi
Further Information

Publication History

Publication Date:
27 February 2013 (online)

We read with interest the article by Lutz et al. which indicated high accuracy of endosonography (EUS) as a diagnostic tool for extrahepatic involvement of primary sclerosing cholangitis (PSC) [1]. The study included 33 patients with cholestatic hepatopathy and a history of inflammatory bowel disease and/or a positive perinuclear anti-neutrophil cytoplasmic antibodies test (pANCA). Magnetic resonance cholangiography (MRC), endoscopic retrograde cholangiography (ERC), or liver biopsy were also used to complete the diagnostic work-up. The authors set four EUS criteria of PSC with extrahepatic disease, and when two of them were present, sensitivity and specificity of predicting PSC were noted to be 76.4 % and 100 % with positive and negative predictive values of 100 % and 79 %, respectively.

Although ERC is the criterion standard test, it is an invasive procedure with an inherent risk for complications. Therefore, MRC has replaced ERC for diagnostic cholangiography in the diagnostic algorithm of patients with suspected PSC [2]. However, MRC can be inadequate for the delineation of intrahepatic involvement in patients with early PSC and shows only poor or moderate success in revealing extrahepatic involvement of this disease [3] [4]. Thus, the driving force of the prospective study by Lutz et al. seemed to be to suggest a new and reliable diagnostic tool such as EUS, which is less invasive and less risky compared with ERC for patients in whom MRC is suspicious or inadequate for the clear delineation of biliary lesions of PSC. However, the design of the study, which was reported to be a prospective one, is flawed and we would like to comment on this.

Only 9 of the 33 patients had the opportunity to undergo MRC examination; 14 underwent ERC and 17 underwent liver biopsy. Although this was a prospective study, it is difficult to understand why all the study patients did not undergo MRC examination first. It is also not acceptable for patients to undergo ERC or biopsy as the first diagnostic tool due to the invasiveness and potential risks associated with these procedures.

Another issue with this paper is that the bile duct wall on duodenal EUS usually appears as a single hypoechoic layer in most cases [5]. A two- or three-layered sonographic appearance is best appreciated on intraductal ultrasonography. In a two-layered structure, the outer hyperechoic layer represents fat in the subserosa, the serosa, and the interface area between the serosa and nearby organs. Thus, we believe that the measurements done on the two-layered appearance on duodenal EUS examination in this study seem to be unreliable. Additionally, any cholangitis, or even autoimmune pancreatitis, can produce EUS findings similar to those of PSC. Thus, EUS is not specific for PSC and will miss all cases of intrahepatic PSC.

We believe that MRC keeps its value as the first screening tool in the diagnostic algorithm of patients who have findings suspicious for PSC. Duodenal EUS examination with a good safety profile might be a useful tool for the diagnosis of PSC; however, more prospective studies are required to assess the duodenal EUS criteria for the diagnosis of PSC involving the extrahepatic biliary tree. Additionally, a prospective assessment comparing MRC and EUS may be also valuable in the evaluation of a patient with potential PSC. Until then, EUS findings need to be confirmed by another method such as ERC and/or liver biopsy in patients who have findings suspicious for PSC on MRC.

 
  • References

  • 1 Lutz HH, Wasmuth HE, Streetz K et al. Endoscopic ultrasound as an early diagnostic tool for primary sclerosing cholangitis: a prospective pilot study. Endoscopy 2012; 44: 934-939
  • 2 Beuers U, Boberg KM, Chapman MH et al. EASL Clinical Practice Guidelines: management of cholestatic liver diseases. J Hepatol 2009; 51: 237-267
  • 3 Moff SL, Kamel IR, Eustace J et al. Diagnosis of primary sclerosing cholangitis: a blinded comparative study using magnetic resonance cholangiography and endoscopic retrograde cholangiography. Gastrointest Endosc 2006; 64: 219-223
  • 4 Weber C, Kuhlencordt R, Grotelueschen R et al. Magnetic resonance cholangiopancreatography in the diagnosis of primary sclerosing cholangitis. Endoscopy 2008; 40: 739-745
  • 5 Mesenas S, Vu C, Doig L et al. Duodenal EUS to identify thickening of the extrahepatic biliary tree wall in primary sclerosing cholangitis. Gastrointest Endosc 2006; 63: 403-408