A new look on liver anatomy: Needs and means to go beyond the Couinaud scheme

Abstract

The paper by Majno et al. [1], in this issue of the journal, makes the interesting proposal that we should retain the Couinaud’s division of the liver into 8 segments but that we should be ready to break free from it when, as radiologists and surgeons, we perform the complex procedures that the modern treatment of surgical liver diseases requires. Claude Couinaud, a late colleague and friend, wrote an almost illegible book detailing the anatomy of the liver and its variations [2]. Hidden in this book, there was the overarching conclusion that in most cases one could extract a simplified general pattern, in which 8 portal segments could be recognized (for the working summary of this representation, see the paper of Majno et al. in this issue, and a recent proposal for modification) [1,3]. Couinaud’s system was popularized by two articles that I wrote in the early ‘80s, at the dawn of modern liver surgery, offering a more accessible description of Couinaud’s work, and showing that liver surgery could and should be practiced having the segmental units in mind [4,5]. In the article I stressed that the main landmarks were the three hepatic veins and the portal bifurcation. Axial imaging such as CT and MRI has lent itself beautifully to the use of Couinaud’s coordinates, because the three hepatic veins and the portal bifurcation are so easy to recognise. Focal lesions can be described according to this system regardless whether the portal branches beyond the portal bifurcation follow it or not. But does modern liver surgery fit to the Couinaud’s scheme? Majno et al. based on the literature and their experience as surgeons and anatomists (the readers are encouraged to study in detail the additional material) show that it does not [1]. This may mean practicing the principles of segmental surgery on smaller units than Couinaud’s 8 segments (on units that we could call subsegments), but also on larger units corresponding to branches that do not follow the pattern of Couinaud, hence their more neutral denomination of ‘‘tailored territorial liver resections’’, implying that these units do not need to be systematised, only recognised and respected. I agree with this