Major Diagnostic Category


The Major Diagnostic Categories are formed by dividing all possible principal diagnoses into 25 mutually exclusive diagnosis areas. MDC codes, like diagnosis-related group codes, are primarily a claims and administrative data element unique to the United States medical care reimbursement system. DRG codes also are mapped, or grouped, into MDC codes.
The diagnoses in each MDC correspond to a single organ system or cause and, in general, are associated with a particular medical specialty. MDC 1 to MDC 23 are grouped according to principal diagnoses. Patients are assigned to MDC 24 with at least two significant trauma diagnosis codes from different body site categories. Patients assigned to MDC 25 must have a principal diagnosis of an HIV Infection or a principal diagnosis of a significant HIV related condition and a secondary diagnosis of an HIV Infection.
MDC 0, unlike the others, can be reached from a number of diagnosis/procedure situations, all related to transplants. This is due to the expense involved for the transplants so designated and because these transplants can be needed for a number of reasons which do not all come from one diagnosis domain. DRGs which reach MDC 0 are assigned to the MDC for the principal diagnosis instead of to the MDC associated with the designated DRG.

List of Major Diagnostic Categories

MDCDescriptionMS-DRG
0Pre-MDC001 - 017
1Diseases and Disorders of the Nervous System020 - 103
2Diseases and Disorders of the Eye113 - 125
3Diseases and Disorders of the Ear, Nose, Mouth And Throat129 - 159
4Diseases and Disorders of the Respiratory System163 - 208
5Diseases and Disorders of the Circulatory System215 - 316
6Diseases and Disorders of the Digestive System326 - 395
7Diseases and Disorders of the Hepatobiliary System And Pancreas405 - 446
8Diseases and Disorders of the Musculoskeletal System And Connective Tissue453 - 566
9Diseases and Disorders of the Skin, Subcutaneous Tissue And Breast573 - 607
10Diseases and Disorders of the Endocrine, Nutritional And Metabolic System614 - 645
11Diseases and Disorders of the Kidney And Urinary Tract652 - 700
12Diseases and Disorders of the Male Reproductive System707 - 730
13Diseases and Disorders of the Female Reproductive System734 - 761
14Pregnancy, Childbirth And Puerperium765 - 782
15Newborn And Other Neonates 789 - 795
16Diseases and Disorders of the Blood and Blood Forming Organs and Immunological Disorders799 - 816
17Myeloproliferative DDs 820 - 849
18Infectious and Parasitic DDs 853 - 872
19Mental Diseases and Disorders876 - 887
20Alcohol/Drug Use or Induced Mental Disorders894 - 897
21Injuries, Poison And Toxic Effect of Drugs901 - 923
22Burns927 - 935
23Factors Influencing Health Status and Other Contacts with Health Services939 - 951
24Multiple Significant Trauma955 - 965
25Human Immunodeficiency Virus Infection969 - 977
MDC Category Missing981 - 989; 998,999