M31.1
Thrombotic microangiopathy
Not billable — category only FY2026 2025-10-01 → 2026-09-30
Exclusions 11 never code together
M30-M36block
Excludes1
- autoimmune disease, single organ or single cell-type -code to relevant condition category
M00-M99chapter
Excludes2
- arthropathic psoriasis (L40.5-)L40.5-
- certain conditions originating in the perinatal period (P04-P96)P04-P96
- certain infectious and parasitic diseases (A00-B99)A00-B99
- compartment syndrome (traumatic) (T79.A-)T79.A-
- complications of pregnancy, childbirth and the puerperium (O00-O9A)O00-O9A
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Q00-Q99
- endocrine, nutritional and metabolic diseases (E00-E88)E00-E88
- injury, poisoning and certain other consequences of external causes (S00-T88)S00-T88
- neoplasms (C00-D49)C00-D49
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)R00-R94
Excludes1 — never code together. The excluded condition and this one are mutually exclusive.
Excludes2 — not included here, but the patient may have both. Code both when documented.
Instructional notes 5
M30-M36block
Includes
- autoimmune disease NOS
- collagen (vascular) disease NOS
- systemic autoimmune disease
- systemic collagen (vascular) disease
M00-M99chapter
Notes
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Index entries leading here filed at null
No alphabetic index entry points at this code.
Alongside this code 9 same parent — M31
M31.0 Hypersensitivity angiitis M31.2 Lethal midline granuloma M31.3 Wegener's granulomatosis category M31.4 Aortic arch syndrome [Takayasu] M31.5 Giant cell arteritis with polymyalgia rheumatica M31.6 Other giant cell arteritis M31.7 Microscopic polyangiitis M31.8 Other specified necrotizing vasculopathies M31.9 Necrotizing vasculopathy, unspecified
Subordinate codes 3
Additional references
AHA Coding Clinic® Licence required
Official coding advice for this code. Published by the American Hospital Association. Not included in this installation.