Crystal's Coding Hub

Recent Notes

G35.C2

Properties3
codeG35.C2
code_titleNon-active secondary progressive multiple sclerosis
statusActive ✅

11 min read

🧬 ICD-10 CM G35.C2 — Non-Active Secondary Progressive Multiple Sclerosis

Billable Code Confirmed

ICD-10 CM G35.C2 is a valid, billable 5-character ICD-10-CM code for FY2026. All required characters are present: G35 (category) + .C (secondary progressive phenotype) + 2 (non-active / without current disease activity). No additional characters are required.

Non-Billable Parent Codes — Never Submit These

  • ❌ G35 — 3-character header — missing phenotype and activity status
  • ❌ G35.C — 4-character header — missing activity status

Always submit G35.C2 (all 5 characters) when SPMS is documented and there is no current inflammatory disease activity.

Clinical Context: What "Non-Active" Means

ICD-10 CM G35.C2 captures secondary progressive MS in a state without current disease activity. “Non-active” means the patient has stable MRI — no new or enlarging T2/FLAIR lesions and no gadolinium-enhancing (Gd+) lesions — and no clinical relapse during the assessment period. Disability may still slowly accumulate (the defining feature of the progressive phase), but there is no superimposed inflammatory activity. Contrast this with G35.C1 (active SPMS), where new lesions or a clinical relapse are present, and G35.C0 (unspecified SPMS), where activity status is not documented.

Code Classification

ICD-10-CM Diagnosis Code — Fields for wRVU, assistant payable, and global period are not applicable. For associated inpatient profee and facility procedure coding, see the CPT Procedural Crosswalk and ICD-10-PCS Crosswalk sections below.

🔍 Code Description

ICD-10 CM G35.C2 classifies Non-active secondary progressive multiple sclerosis. It denotes secondary progressive MS (SPMS) in a phase of steady, gradual disability accumulation without current inflammatory activity — meaning no clinical relapses and no new or enhancing lesions on imaging since the prior evaluation.

SPMS is the phenotype that follows an initial relapsing-remitting (RRMS) course. Over time, the relapsing pattern transitions into a steadily progressive course in which disability worsens gradually, with or without occasional relapses. The “non-active” modifier indicates that, at the time of this assessment, the autoimmune inflammatory component is quiescent: the patient is not having a relapse and surveillance MRI shows no new Gd-enhancing or new/enlarging T2/FLAIR lesions. This is a clinically meaningful distinction because it documents stable inflammatory status while still capturing the progressive, disabling nature of the disease.

🌳 Code Tree / Hierarchy

G35 Multiple Sclerosis ❌ Non-billable
│
├── G35.A Relapsing-remitting multiple sclerosis (RRMS) ✅ Billable
│
├── G35.B Primary progressive multiple sclerosis (PPMS) ❌ Non-billable
│   ├── G35.B0 PPMS, unspecified ✅ Billable
│   ├── G35.B1 Active PPMS ✅ Billable
│   └── G35.B2 Non-active PPMS ✅ Billable
│
├── G35.C Secondary progressive multiple sclerosis (SPMS) ❌ Non-billable
│   ├── G35.C0 SPMS, unspecified ✅ Billable
│   ├── G35.C1 Active SPMS ✅ Billable
│   └── G35.C2 Non-active SPMS ◀ THIS CODE ✅ Billable
│
└── G35.D Multiple sclerosis, unspecified ✅ Billable

Specificity Drives Accurate Risk Capture

The FY2026 MS category requires coders to capture both the phenotype (RRMS / PPMS / SPMS) and the current activity status (unspecified / active / non-active). Coding G35.C2 correctly documents a patient in the secondary progressive phase whose disease is currently quiescent, which is clinically and actuarially distinct from active disease (G35.C1).

✅ Includes

The following clinical terms and scenarios map to G35.C2 when documented for an SPMS patient:

  • Non-active secondary progressive MS
  • SPMS with stable surveillance MRI (no new or enhancing lesions)
  • SPMS without clinical relapse during the assessment period
  • SPMS in a progressive phase with no current inflammatory activity

❌ Excludes

Excludes 1 — Cannot Be Coded Simultaneously with G35.C2

CodeDescriptionNote
G36.0Neuromyelitis optica [Devic]Mutually exclusive — NMO involves antibodies targeting aquaporin-4 (AQP4); pathophysiology is distinct from MS. Code G36.0 instead if NMO is confirmed.
G36.9Acute disseminated demyelinationADEM is typically a monophasic post-infectious process, unlike the chronic, progressive nature of SPMS.
G37.81MOGADMyelin oligodendrocyte glycoprotein antibody-associated disease is a distinct demyelinating syndrome with a different clinical course.

Excludes 1 Violation Risk

You cannot assign MS codes concurrently with other specified central demyelinating diseases like NMO or MOGAD. If a patient’s diagnosis is revised from MS to NMO based on autoantibody testing, use the NMO code exclusively.

Excludes 2 — May Be Coded in Addition if Separately Present

CodeDescriptionNote
G37.-Other demyelinating diseases of central nervous systemMay be coded additionally if a completely distinct condition is present.

📋 Clinical Overview

Phenotype & Activity Distinction — Understanding “Non-Active” SPMS

The FY2026 MS category requires coders to distinguish not only the phenotype but the current disease activity. For SPMS this distinction must be explicitly documented by the neurologist.

FeatureNon-Active (G35.C2)Active (G35.C1)Unspecified (G35.C0)
Clinical PresentationGradual baseline progression but no clinical relapse during the period.New or worsening neurological symptoms from a relapse superimposed on progression.Activity status not documented or not assessable.
Radiographic PresentationStable MRI — no new/enlarging T2/FLAIR lesions and no Gd-enhancing lesions vs. prior scan.New or enlarging T2/FLAIR lesions and/or active Gd-enhancing lesions.No MRI activity statement available.
Typical Documentation”SPMS, clinically and radiographically stable, no current activity.""SPMS with relapse” or “new enhancing lesion.""SPMS” with no activity qualifier.

CDI Query Trigger — Activity Not Documented

If the physician documents “SPMS” without addressing relapse or MRI activity, the default is G35.C0 (unspecified). If the record contains evidence one way or the other (a stable surveillance MRI, or conversely a new lesion/relapse), a CDI query is warranted to assign the precise code — G35.C2 for non-active or G35.C1 for active. If activity later appears, the code shifts to G35.C1.

Manifestations & Symptom Burden

Even without current inflammatory activity, SPMS patients typically carry a substantial chronic disability burden from prior accumulated damage, commonly including:

  • Progressive spastic paraparesis: Chronic stiffness and weakness in the lower extremities.
  • Chronic ataxia and balance impairment: Persistent fall risk.
  • Neurogenic bowel/bladder dysfunction: Retention or incontinence.
  • Cognitive impairment and fatigue: Stable but functionally limiting.

Coding Manifestations

Always code the documented manifestations to fully capture the patient’s complexity. These codes support the medical decision making (MDM) regarding chronic disability. Examples include:

  • R27.0 — Ataxia, unspecified
  • M62.838 — Other muscle spasm
  • N31.9 — Neuromuscular dysfunction of bladder, unspecified
  • R53.83 — Other fatigue
  • Z99.3 — Dependence on wheelchair

💰 HCC Risk Adjustment (CMS-HCC v28)

FieldDetail
CMS-HCC Model Versionv28
HCC Assignment✅ Mapped
HCC CategoryHCC 198 — Multiple Sclerosis
RAF Coefficient~0.45 - 0.65 (varies by demographic/status)

G35.C2 maps directly to an HCC and contributes significantly to the RAF score.

Capture Annually & Verify the Crosswalk

SPMS is a lifelong condition; it must be evaluated, documented, and coded at least once every calendar year to be calculated in the patient’s risk profile. The C2 (non-active) character reflects current quiescence but does not reduce the chronic disability burden. The HCC number shown reflects CMS-HCC v28 (HCC 198) — the older v24 model used a different HCC number. Always verify against the current CMS-HCC crosswalk for the applicable payment year.

🏥 MS-DRG Assignment

MDC 01 — Diseases and Disorders of the Nervous System

DRGTitleEst. Relative Weight*
DRG 058Multiple Sclerosis & Cerebellar Ataxia with MCC~1.30 - 1.50
DRG 059Multiple Sclerosis & Cerebellar Ataxia with CC~0.90 - 1.10
DRG 060Multiple Sclerosis & Cerebellar Ataxia without CC/MCC~0.65 - 0.80

Approximate. Verify against IPPS FY2026 Final Rule tables.

Sequencing and Complications

A patient with G35.C2 is still susceptible to inpatient admissions for complications of their chronic disability (e.g., severe UTI, falls/fractures, aspiration). When admitted for a complication, sequence the acute complication as the principal diagnosis. G35.C2 acts as a Comorbidity (CC) that accurately reflects the severe neurologic baseline.

🔗 Related ICD-10-CM Codes

Activity Variants (within G35.C — mutually exclusive)

CodeDescription
G35.C2Non-active secondary progressive MS ← This Code
G35.C1Active secondary progressive MS
G35.C0Secondary progressive MS, unspecified

Mutual Exclusivity

G35.C0, G35.C1, and G35.C2 are mutually exclusive — assign only one per encounter based on the documented activity status. If inflammatory activity (a relapse or a new/enhancing lesion) appears, the code shifts to G35.C1.

Phenotype Variants

CodeDescription
G35.ARelapsing-remitting multiple sclerosis (RRMS)
G35.BPrimary progressive multiple sclerosis (PPMS) — B0/B1/B2
G35.DMultiple sclerosis, unspecified

🛠️ Commonly Associated CPT Codes (Neurology / PM&R)

Outpatient and Profee Setting Context

The CPT codes below are frequently associated with surveillance and maintenance management of SPMS in profee and outpatient settings.

CPT CodeDescriptionProfee Coding Notes (Modifier 26)
70553MRI brain without contrast, followed by contrastSurveillance MRI confirming the absence of new Gd-enhancing lesions supports the “non-active” status. Append -26 if interpreting in a facility.
72156MRI cervical spine without and with contrastSpinal cord surveillance is important in SPMS. Append -26 for profee.
99214E/M established patient, moderate complexityStable SPMS follow-up commonly meets moderate MDM criteria.
96365Intravenous infusion, for therapy; initial, up to 1 hourUsed when a maintenance DMT (e.g., Ocrelizumab) is continued.
96366Intravenous infusion, each additional hourRequired for prolonged biologic infusions.

NCCI Bundling Considerations

  • Infusion services (96365) billed on the same day as an E/M visit (99214) require the E/M to be significant and separately identifiable. Modifier -25 must be appended to the E/M code.

🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)

When G35.C2 is an inpatient diagnosis, these PCS codes are relevant for interventions targeting the chronic disability.

PCS SectionBody SystemRoot OperationClinical Application
3 (Administration)E (Physiological Systems)0 (Introduction)Infusion of Disease-Modifying Therapy. Example: 3E033GC (Intro of Other Therapeutic Sub into Peripheral Vein).
0 (Medical & Surgical)0 (Central Nervous System)H (Insertion)Implantation of intrathecal baclofen pump for severe chronic spasticity. Example: 00H00MZ (Insertion of Infusion Device into Brain/Meninges).

💊 Coding Scenarios and Examples

Scenario 1 — Outpatient Neurology Evaluation: Stable Surveillance

Clinical Vignette: A 54-year-old female with a 20-year MS history that transitioned from RRMS to a secondary progressive course presents for her annual neurology follow-up. Her EDSS has been stable at 5.5 for the past two years. Recent brain and C-spine MRIs show no new T2/FLAIR lesions and no gadolinium-enhancing lesions compared with the prior study, and she has had no relapses. Impression: Secondary progressive MS, non-active. Continue current maintenance regimen.

CPT / HCPCS (Profee):

  • 99214 — Office or other outpatient visit, established patient, moderate complexity

ICD-10-CM:

  • G35.C2 — Non-active secondary progressive multiple sclerosis
  • R26.2 — Difficulty in walking, not elsewhere classified

Scenario 2 — Inpatient Admission for Dysphagia Complication

Clinical Vignette: A 62-year-old male with advanced non-active secondary progressive MS is admitted with severe aspiration pneumonia. His swallowing has gradually worsened over time due to chronic MS disability (no acute relapse and a stable recent MRI). He requires IV antibiotics and a speech therapy evaluation for a PEG tube.

Principal Diagnosis:

  • J69.0 — Pneumonitis due to inhalation of food and vomit (Reason for admission)

Secondary Diagnoses:

  • G35.C2 — Non-active secondary progressive multiple sclerosis (Captures the severe chronic baseline driving the dysphagia; acts as a CC)
  • R13.10 — Dysphagia, unspecified

MS-DRG Assignment: The aspiration pneumonia principal diagnosis groups this to MDC 04 (Respiratory System). The inclusion of G35.C2 as a CC elevates the DRG (e.g., DRG 194 — Simple Pneumonia and Pleurisy with CC).

Scenario 3 — CDI Query: Clarifying Activity Status

Clinical Vignette: A patient is seen in the outpatient infusion center. The clinic note states: “Patient with secondary progressive MS here for scheduled maintenance infusion. Clinically stable, no relapse since last visit.” A surveillance MRI report in the chart reads “no new or enhancing lesions.”

Action / Outcome: The documentation supports the absence of current disease activity. Rather than defaulting to G35.C0 (unspecified), the coder may query to confirm the non-active status, which the record clearly supports.

Query Response: The physician confirms “Secondary progressive MS, non-active — clinically and radiographically stable.”

Corrected ICD-10-CM Coding:

  • G35.C2 — Non-active secondary progressive multiple sclerosis

⚠️ Coding Pitfalls and Tips

Pitfall or Tip
❌Do not confuse G35.C2 (non-active SPMS) with G35.C1 (active SPMS). “Active” requires a relapse or new/enhancing MRI lesions. “Non-active” requires a stable MRI and no relapse. If activity appears, shift to C1.
❌Do not confuse SPMS (G35.C) with PPMS (G35.B). SPMS follows an initial relapsing-remitting course before becoming progressive; PPMS is progressive from onset. They are different fourth-character phenotypes.
❌Do not assign G35.C0, C1, and C2 together. They are mutually exclusive — only one per encounter based on documented activity.
✅Use the unspecified code only when activity is truly undocumented. If the record supports stable status, G35.C2 is more specific than G35.C0.
✅Sequence acute complications first for inpatients. If the patient is admitted for a fall or pneumonia secondary to chronic disability, code the acute condition first; G35.C2 is sequenced secondarily but remains critical for DRG CC/MCC capture.
✅Capture all manifestations. Documenting specific manifestations (dysphagia, ataxia, muscle weakness) paints a clear picture of MDM complexity and the chronic disability burden.

📚 Sources

  1. CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026.
  2. National Multiple Sclerosis Society. Types of MS: Secondary Progressive MS and Disease Activity.
  3. Lublin, F. D., et al. (2014). Defining the clinical course of multiple sclerosis: the 2013 revisions. Neurology, 83(3), 278-286. (Source for active/non-active and progressive course definitions).
  4. CMS. Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings. (Verify HCC 198 against the current crosswalk.)
  5. CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual. MDC 01 logic tables.
  6. AMA. CPT Professional Edition 2026. Neurology and Medicine subsections.

Graph View