A New Quantitative Classification of the Extrahepatic Biliary Tract Related to Cystic Duct Implantation

Matteo Renzulli,Stefano Brocchi,Giovanni Marasco,Daniele Spinelli,Caterina Balacchi,Massimo Barakat,Irene Pettinari,Rita Golfieri

doi:10.1007/s11605-020-04852-8

Matteo Renzulli, Stefano Brocchi + Show 6 more

Open Access

https://doi.org/10.1007/s11605-020-04852-8

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Abstract

BackgroundKnowledge regarding biliary anatomy and its variations, including the cystic duct (CD), is important in the pre-surgical setting and for predicting biliary diseases. However, no large series has focused on CD evaluation using a quantitative analysis. The primary aim of this prospective study was to create a ‘taxonomic’ classification of CD anatomy in a large cohort of subjects who underwent magnetic resonance cholangiopancreatography (MRCP). The secondary aim was to evaluate the correlations between extrahepatic bile duct (EHBD) variants and biliary diseases. MethodsWe enrolled patients who underwent MRCP for different clinical indications from January 2017 to May 2019. Demographical, anatomical and clinical data were evaluated using statistical analyses, as appropriate. The anatomical assessment of EHBD was performed using the standard classification for CD in low, medium, and high insertions, and the lengths of CD to the duodenal papilla (DP), and EHBD was determined to conduct a new quantitative analysis. ResultsThe final study population comprised 1004 subjects. A new classification for EHBD as per the percentile distribution of the ratio CDDP/EHBD was designed, and the following categories were obtained: type 1 (below the 25th percentile) for CDDP/EHBD ratio ≤ 50%; type 2 (25th to 75th percentile) for CDDP/EHBD ratio 51–75% and type 3 (above the 75th percentiles) for CDDP/EHBD ratio > 75%. Type 1 of the new classification of CD implantation was significantly superior in terms of the detection of low, medial and intra-pancreatic CD that was significantly correlated with a high risk of choledochal lithiasis in comparison with the standard classification (P < 0.001). ConclusionsThe new classification of CD implantation enables identification of the vast majority of intra-pancreatic CDs that are correlated with a high risk of choledochal lithiasis in a single category (type 1) that is easy to identify using imaging.

Highlights

Considering the arrangement of the segmental bile ducts, the ‘classical’ anatomy of the intra-hepatic biliary tree includes the right posterior duct (RPD) draining the liver segments VI and VII and the right anterior duct (RAD) draining the liver segments V and VIII to join the right hepatic duct (RHD)
Type 1 of the new classification of cystic duct (CD) implantation was significantly superior in terms of the detection of low, medial and intra-pancreatic CD that was significantly correlated with a high risk of choledochal lithiasis in comparison with the standard classification (P < 0.001)
The new classification of CD implantation enables identification of the vast majority of intra-pancreatic CDs that are correlated with a high risk of choledochal lithiasis in a single category that is easy to identify using imaging

Summary

Introduction

Considering the arrangement of the segmental bile ducts, the ‘classical’ anatomy of the intra-hepatic biliary tree includes the right posterior duct (RPD) draining the liver segments VI and VII and the right anterior duct (RAD) draining the liver segments V and VIII to join the right hepatic duct (RHD). The RHD and LHD join in the common hepatic duct (CHD) at the hepatic hilus.[1,2] After the confluence of the cystic duct (CD), the CHD forms the common bile duct (CBD) that drains the bile into the duodenum through the papilla of Vater.[1,3] This normal biliary anatomy of the intra-hepatic ducts is present in 58–64.5% of the population.[2,4] Many anatomic variations of the intra-hepatic ducts have been described in the literature, RPD that is more often described in its different insertions.[1,4,5] In addition, with respect to the extrahepatic biliary ducts (EHBDs), the described normal anatomy is present in only approximately 53% of the population. The secondary aim was to evaluate the correlations between extrahepatic bile duct (EHBD) variants and biliary diseases

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