What is the ATOM (A, B, C, D, E) classification for bile duct injuries?

ATOM Classification of Bile Duct Injury

The ATOM classification is the most comprehensive and recent classification system for bile duct injuries, integrating Anatomical damage, Time of detection, and Mechanism of injury, and is recommended by the World Society of Emergency Surgery guidelines as the preferred classification system. 1

Anatomical Characteristics (A)

• Injuries are first categorized based on whether they involve the main biliary duct (MBD) or non-main biliary duct (NMBD) 2
• Main biliary duct (MBD) injuries are further classified by anatomical level (1-6) 2
• Each injury is described as complete (C) or partial (P) 2
• Loss of substance (LS) is noted when applicable 2, 3
• Vasculobiliary injury (VBI) is documented as present (VBI+) or absent (VBI-), with specific injured vessel noted (RHA, LHA, CHA, PV, MV) 2, 1

Time of Detection (T)

• Early intraoperative (Ei): detected during the initial operation 2, 3
• Early postoperative (Ep): detected in the immediate postoperative period 2, 3
• Late (L): detected after discharge or during follow-up 2, 3

Mechanism of Injury (M)

• Mechanical (Me): direct surgical trauma from instruments 2, 3
• Energy driven (ED): thermal injury from electrocautery or other energy devices 2, 3

Clinical Significance of ATOM Classification

• The ATOM classification guides appropriate management strategies based on injury characteristics 1
• For minor injuries (partial injuries without tissue loss), direct repair with or without T-tube placement may be considered 2
• For major injuries (complete transection or with tissue loss), hepaticojejunostomy is the treatment of choice 2
• Early repair (on-table up to 72h) may be considered with appropriate surgical expertise 2
• Complex vasculobiliary injuries should be delayed rather than attempted intraoperatively, even by expert HPB surgeons 2, 4

Advantages of ATOM Classification

• Integrates all information on bile duct injuries regardless of original classification used 3
• Facilitates epidemiologic and comparative studies 3
• Guides appropriate preventive measures 3
• Better directs therapeutic indications for iatrogenic bile duct injuries 3
• Includes vascular injury components, which are critical for management decisions 1, 4

Implementation in Clinical Practice

• The World Society of Emergency Surgery guidelines strongly recommend knowing both Strasberg's classification and the ATOM classification 1
• ATOM classification implementation should be promoted due to its comprehensive nature 1
• When describing bile duct injuries, operative reports must include detailed information about anatomical landmarks, variations, and vascular structures involved 1
• Studies have shown that the ATOM classification can describe the complexity of bile duct injuries more accurately than other classification systems 5

Comparison to Other Classification Systems

• The Bismuth classification (1982) was the first published system focused on biliary injury location 1
• The Strasberg classification (1995) is currently the most commonly used classification but lacks comprehensive vascular injury assessment 1, 6
• The Stewart-Way and Lau classifications include vascular injury components but are less comprehensive than ATOM 1
• The ATOM classification encompasses all aspects of bile duct injuries that other classifications may miss 7, 5