Clinical and anatomical basis for the classification of the structural parts of liver

Progress of diagnostic human's liver imaging (ultrasound, computerized tomography, magnetic nuclear resonance, etc.) stimulates development of modern liver surgery. Therefore, before and during the operation, surgeons and radiologists can determine the site and extent of liver damage, its relationship with blood vessels and ascertain which part of the liver should be resected. For this reason, physicians have to know anatomical and clinical peculiarities of the liver. Naming of the parts of this complex inner organ is still highly varied: parts, halves, lobes, divisions, sectors, segments, and subsegments. Our understanding and explanation of liver composition are still defined differently among anatomists, surgeons, and radiologists, thus not only confusing less experienced specialists, but also increasing probability of mistakes. Such lack of communication aggravates the design of an operation plan and its documentation, which frequently may even result in undesirable legal consequences. Unified terms among surgeons and radiologists are of importance not only in clinical settings of one country, but also on the international level (e.g. when comparing results of surgery). The smallest parts of the liver are defined using C. Couinaud's segmentation system, allowing for a precise identification of the site of liver damage, as well as to plan methods of segment resection that would protect the remaining hepatic tissue. The classification that best meets the needs of surgeons and radiologists was the one proposed by H. Bismuth. We suggest that this classification should also be used by our physicians who are engaged in diagnostics and treatment of hepatic diseases in their practice. We also discuss other classifications used worldwide (those proposed by J. Healey and P. Schroy, N. Goldsmith and R. Woodburne, C. Couinaud, and H. Bismuth) and present recommendations of global societies of anatomists and surgeons.