MS-DRG · FY 2026 v43.0
MS-DRG 816 – Reticuloendothelial and Immunity Disorders without CC/MCC
A Medical DRG in MDC 16 (Diseases & Disorders of Blood, Blood Forming Organs, Immunologic Disorders). Inpatient cases group to DRG 816 when the ICD-10-CM principal diagnosis is one of the 137 codes listed below and no secondary diagnosis on the CC or MCC lists is present. Its FY 2026 relative weight is 0.6320 with a geometric mean length of stay of 2.0 days.
Medical DRG – assigned by principal diagnosis✓ Official CMS v43.0 dataset
0.6320
Relative Weight
2.0
Geometric Mean LOS (days)
2.3
Arithmetic Mean LOS (days)
137
Principal Diagnosis Codes
Severity family
DRG 814with MCCWeight 2.1267 · GMLOS 4.7 daysDRG 815with CCWeight 1.0140 · GMLOS 2.9 daysDRG 816without CC/MCCWeight 0.6320 · GMLOS 2.0 days
How a case is assigned to DRG 816
The grouper first assigns the case to MDC 16 from the principal diagnosis and finds no qualifying operating-room procedure (this is a Medical DRG; ICD-10-PCS codes do not drive assignment here), then applies the severity split from secondary diagnoses: with MCC → 814; with CC → 815; without CC/MCC → 816.
ICD-10-CM
Principal Diagnosis Codes 137 codes · 30 categories
137 of 137 shown
A18 Tuberculosis of other organs2 codes
A28 Other zoonotic bacterial diseases, not elsewhere classified1 code
- A28.1 Cat-scratch disease
D15 Benign neoplasm of other and unspecified intrathoracic organs1 code
- D15.0 Benign neoplasm of thymus
D18 Hemangioma and lymphangioma, any site1 code
- D18.1 Lymphangioma, any site
D36 Benign neoplasm of other and unspecified sites1 code
- D36.0 Benign neoplasm of lymph nodes
D3A Benign neuroendocrine tumors1 code
- D3A.091 Benign carcinoid tumor of the thymus
D47 Other neoplasms of uncertain behavior of lymphoid, hematopoietic and related tissue3 codes
D68 Other coagulation defects7 codes
D72 Other disorders of white blood cells21 codes
- D72.10 Eosinophilia, unspecified
- D72.110 Idiopathic hypereosinophilic syndrome [IHES]
- D72.111 Lymphocytic Variant Hypereosinophilic Syndrome [LHES]
- D72.118 Other hypereosinophilic syndrome
- D72.119 Hypereosinophilic syndrome [HES], unspecified
- D72.12 Drug rash with eosinophilia and systemic symptoms syndrome
- D72.18 Eosinophilia in diseases classified elsewhere
- D72.19 Other eosinophilia
- D72.810 Lymphocytopenia
- D72.818 Other decreased white blood cell count
- D72.819 Decreased white blood cell count, unspecified
- D72.820 Lymphocytosis (symptomatic)
- D72.821 Monocytosis (symptomatic)
- D72.822 Plasmacytosis
- D72.823 Leukemoid reaction
- D72.824 Basophilia
- D72.825 Bandemia
- D72.828 Other elevated white blood cell count
- D72.829 Elevated white blood cell count, unspecified
- D72.89 Other specified disorders of white blood cells
- D72.9 Disorder of white blood cells, unspecified
D73 Diseases of spleen9 codes
D75 Other and unspecified diseases of blood and blood-forming organs7 codes
- D75.0 Familial erythrocytosis
- D75.1 Secondary polycythemia
- D75.838 Other thrombocytosis
- D75.839 Thrombocytosis, unspecified
- D75.89 Other specified diseases of blood and blood-forming organs
- D75.9 Disease of blood and blood-forming organs, unspecified
- D75.A Glucose-6-phosphate dehydrogenase (G6PD) deficiency without anemia
D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissue3 codes
D77 Other disorders of blood and blood-forming organs in diseases classified elsewhere1 code
- D77 Other disorders of blood and blood-forming organs in diseases classified elsewhere
D80 Immunodeficiency with predominantly antibody defects7 codes
- D80.0 Hereditary hypogammaglobulinemia
- D80.1 Nonfamilial hypogammaglobulinemia
- D80.2 Selective deficiency of immunoglobulin A [IgA]
- D80.3 Selective deficiency of immunoglobulin G [IgG] subclasses
- D80.4 Selective deficiency of immunoglobulin M [IgM]
- D80.5 Immunodeficiency with increased immunoglobulin M [IgM]
- D80.7 Transient hypogammaglobulinemia of infancy
D82 Immunodeficiency associated with other major defects5 codes
- D82.2 Immunodeficiency with short-limbed stature
- D82.3 Immunodeficiency following hereditary defective response to Epstein-Barr virus
- D82.4 Hyperimmunoglobulin E [IgE] syndrome
- D82.8 Immunodeficiency associated with other specified major defects
- D82.9 Immunodeficiency associated with major defect, unspecified
D83 Common variable immunodeficiency5 codes
- D83.0 Common variable immunodeficiency with predominant abnormalities of B-cell numbers and function
- D83.1 Common variable immunodeficiency with predominant immunoregulatory T-cell disorders
- D83.2 Common variable immunodeficiency with autoantibodies to B- or T-cells
- D83.8 Other common variable immunodeficiencies
- D83.9 Common variable immunodeficiency, unspecified
D84 Other immunodeficiencies6 codes
D89 Other disorders involving the immune mechanism, not elsewhere classified18 codes
- D89.0 Polyclonal hypergammaglobulinemia
- D89.2 Hypergammaglobulinemia, unspecified
- D89.3 Immune reconstitution syndrome
- D89.40 Mast cell activation, unspecified
- D89.41 Monoclonal mast cell activation syndrome
- D89.42 Idiopathic mast cell activation syndrome
- D89.43 Secondary mast cell activation
- D89.44 Hereditary alpha tryptasemia
- D89.49 Other mast cell activation disorder
- D89.831 Cytokine release syndrome, grade 1
- D89.832 Cytokine release syndrome, grade 2
- D89.833 Cytokine release syndrome, grade 3
- D89.834 Cytokine release syndrome, grade 4
- D89.835 Cytokine release syndrome, grade 5
- D89.839 Cytokine release syndrome, grade unspecified
- D89.84 IgG4-related disease
- D89.89 Other specified disorders involving the immune mechanism, not elsewhere classified
- D89.9 Disorder involving the immune mechanism, unspecified
E32 Diseases of thymus4 codes
I88 Nonspecific lymphadenitis3 codes
I89 Other noninfective disorders of lymphatic vessels and lymph nodes2 codes
L04 Acute lymphadenitis6 codes
Q89 Other congenital malformations, not elsewhere classified2 codes
R16 Hepatomegaly and splenomegaly, not elsewhere classified1 code
- R16.1 Splenomegaly, not elsewhere classified
R59 Enlarged lymph nodes3 codes
R75 Inconclusive laboratory evidence of human immunodeficiency virus [HIV]1 code
- R75 Inconclusive laboratory evidence of human immunodeficiency virus [HIV]
R76 Other abnormal immunological findings in serum4 codes
S36 Injury of intra-abdominal organs9 codes
- S36.00XA Unspecified injury of spleen, initial encounter
- S36.020A Minor contusion of spleen, initial encounter
- S36.021A Major contusion of spleen, initial encounter
- S36.029A Unspecified contusion of spleen, initial encounter
- S36.030A Superficial (capsular) laceration of spleen, initial encounter
- S36.031A Moderate laceration of spleen, initial encounter
- S36.032A Major laceration of spleen, initial encounter
- S36.039A Unspecified laceration of spleen, initial encounter
- S36.09XA Other injury of spleen, initial encounter
T80 Complications following infusion, transfusion and therapeutic injection1 code
- T80.82XA Complication of immune effector cellular therapy, initial encounter
ICD-10-PCS
Procedure Codes
Procedure codes do not drive assignment for this DRG. DRG 816 is a Medical DRG, assigned from the principal diagnosis above.
Frequently Asked Questions
What is MS-DRG 816?
MS-DRG 816 (Reticuloendothelial and Immunity Disorders without CC/MCC) is a medical DRG in MDC 16 (Diseases & Disorders of Blood, Blood Forming Organs, Immunologic Disorders). Its FY 2026 relative weight is 0.6320 with a geometric mean length of stay of 2.0 days.
What is the difference between DRG 814, 815, 816?
All 3 share the same base category; the severity of secondary diagnoses separates them: 814 (with MCC), 815 (with CC), 816 (without CC/MCC). A major complication or comorbidity (MCC) places the case in the highest-weighted DRG of the family; a CC in the middle; neither in the lowest.
How many diagnosis codes group to DRG 816?
137 ICD-10-CM principal diagnosis codes group to this DRG, spanning 30 three-character categories.
What is the relative weight of DRG 816?
The FY 2026 relative weight of this DRG is 0.6320, meaning reimbursement of roughly 0.63 times the average Medicare inpatient case. Multiply by a hospital's blended base rate for the approximate payment.
← PreviousDRG 815 – Reticuloendothelial and Immunity Disorders with CCNext →DRG 817 – Other Antepartum Diagnoses with O.R. Procedures with MCC
Source: CMS ICD-10 MS-DRG v43.0 Definitions Manual and the FY 2026 IPPS Final Rule (Table 5), effective October 1, 2025 through September 30, 2026. We publish the DRG assignments as CMS defines them and add the navigation, search, and code links.
