Q05.5
BillableCervical spina bifida without hydrocephalus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Q05.5 an HCC code?
Yes. Q05.5 maps to Spinal Cord Disorders/Injuries under the CMS-HCC V28 risk adjustment model (and Spinal Cord Disorders/Injuries under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for Q05.5
For Q05.5 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed Q05.5 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
Q05.5 is the ICD-10-CM diagnosis code for cervical spina bifida without hydrocephalus. A birth defect where the spine doesn't close properly in the neck area, without fluid buildup in the brain. Q05.5 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering congenital malformations of the nervous system (q00-q07).
Under the CMS-HCC V28 risk adjustment model, Q05.5 maps to Spinal Cord Disorders/Injuries (HCC 182) with a community, non-dual, aged base RAF weight of 0.282. Under the older V24 model, Q05.5 mapped to the same category but with a base RAF weight of 0.464 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Confirm that hydrocephalus is explicitly absent or not present; if hydrocephalus exists, use Q05.0 instead. Because Q05.5 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q05.5 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm that hydrocephalus is explicitly absent or not present; if hydrocephalus exists, use Q05.0 instead
- •Document the cervical location clearly to distinguish from other spinal levels
Clinical Significance
Cervical spina bifida without hydrocephalus represents a serious congenital anomaly affecting the neck region of the spine, often associated with significant neurological deficits including potential respiratory compromise. Early recognition and appropriate management are essential for optimizing functional outcomes and preventing complications.
Documentation Requirements
- ✓Specific identification of cervical spine involvement
- ✓Absence of hydrocephalus confirmed by imaging
- ✓Neurological examination findings and deficits
- ✓Respiratory function assessment if applicable
- ✓Surgical history including spinal closure procedures
- ✓Current functional status and mobility assessment
- ✓Associated anomalies or complications
- ✓Ongoing care plan and specialist involvement