ICD-10-CM/PCS MS-DRG v40.1 Definitions Manual
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Since patients can have multiple procedures related to their principal diagnosis during a particular hospital stay, and a patient can be assigned to only one surgical class, the surgical classes in each MDC are defined in a hierarchical order. Patients with multiple procedures are assigned to the highest surgical class in the hierarchy to which one of the procedures is assigned. Thus, if a patient receives both a D&C and a hysterectomy, the patient is assigned to the hysterectomy surgical class because a hysterectomy is higher in the hierarchy than a D&C. Because of the surgical hierarchy, ordering of the surgical procedures on the patient abstract or claim has no influence on the assignment of the surgical class and the MS-DRG. The surgical hierarchy for each MDC reflects the relative resource requirements of various surgical procedures. In some cases a surgical class in the hierarchy is actually an MS-DRG. For example, Arthroscopy is both a surgical class in the hierarchy and MS-DRG 509 in MDC 8, Diseases and Disorders of the Musculoskeletal System and Connective Tissue. In other cases the surgical class in the hierarchy is further partitioned based on other variables such as complications and comorbidities, or principal diagnosis to form multiple MS-DRGs. As an example, in MDC 5, Diseases and Disorders of the Circulatory System, the surgical class for permanent pacemaker implantation is divided into three MS-DRGs (242-244) based on whether or not the patient had no CCs, a CC or an MCC. Appendix D presents the surgical hierarchy for each MDC. Appendix D is organized by MDC with a list of the surgical classes associated with that MDC listed in hierarchical order as well as the MS-DRGs that are included in each surgical class. The names given to the surgical classes in the hierarchy correspond to the names used in the MS-DRG logic tables and in the body of the Definitions Manual.