ICD-10 Code P90: Convulsions of newborn

Key Takeaways

ICD-10 Code P90 (Convulsions of newborn) is a billable, specific ICD-10-CM diagnosis code valid for the 2026 edition, effective October 1, 2025.

P90 applies to neonatal seizures and neonatal convulsions; it excludes benign myoclonic epilepsy in infancy and benign neonatal convulsions (familial), both coded separately under G40.3-.

Coding errors are common at the P90 vs G40.3- boundary: always confirm whether the documentation supports a familial/genetic origin before selecting G40.3-.

Pabau’s clinical documentation tools and claims management software help neonatal care teams assign and bill diagnosis codes accurately from a single platform.

ICD-10 Code P90 is the billable, specific ICD-10-CM diagnosis code for Convulsions of newborn. According to the CDC/NCHS ICD-10-CM coding tool, P90 is a valid, reportable code for the 2026 edition of ICD-10-CM, effective October 1, 2025.

A billable code means it can be used directly on a claim to indicate a diagnosis for reimbursement purposes without requiring a more detailed sub-code.

P90 sits within Chapter 16 of ICD-10-CM, which covers Certain conditions originating in the perinatal period (P00-P96). Within that chapter, it belongs to the P90-P96 block, Other disorders originating in the perinatal period.

The perinatal period is defined as before birth through the 28th day following birth under the CMS ICD-10-CM Official Guidelines for coding and reporting. P90 is used when convulsions or seizures occur in a newborn during this window and no more specific code applies.

Code details and classification

The table below shows the full ICD-10-CM hierarchy for P90 and its key administrative attributes, as maintained by the WHO ICD-10 browser and the CMS tabular list.

Synonyms and alternate terms for P90

Clinicians document neonatal seizure events using several terms that all map to ICD-10 Code P90. Using alternate terminology in a chart note does not require a different code, provided the documentation excludes a familial or genetic etiology. Coders should recognize all of the following as appropriate synonyms for P90, per the ICD List and AAPC guidance.

• Convulsions of newborn
• Neonatal convulsions
• Neonatal seizures
• Seizures of newborn
• Perinatal convulsions
• Neonatal epileptic activity (where documentation does not indicate familial origin)

If the attending physician uses any of these terms in the discharge summary or progress notes, P90 is the appropriate ICD-10-CM code to assign, assuming no Excludes1 conflict applies.

This holds whether the note originates from the NICU or a follow-up GP practice visit. See the section below on the P90 vs G40.3- distinction for when to route to a different code instead.

Excludes notes: What ICD-10 Code P90 does not cover

P90 carries two Excludes1 notes, the more restrictive of the two ICD-10-CM exclusion types. An Excludes1 means the excluded condition and P90 cannot be reported together on the same claim for the same encounter. Each excluded condition has its own specific code and must be coded separately when it applies.

The Excludes1 notes for P90 read:

• Excludes1: Benign myoclonic epilepsy in infancy (G40.3-)
• Excludes1: Benign neonatal convulsions (familial) (G40.3-)

This exclusion matters because both excluded conditions, benign myoclonic epilepsy in infancy and benign neonatal convulsions (familial), are recognized epilepsy syndromes. Both are distinct from convulsions caused by metabolic disturbance, hypoxia, infection, or structural brain injury.

When documentation confirms either diagnosis, G40.3- is the correct code. When origin is unclear or the seizures are attributable to perinatal insult, P90 applies instead. Never assign both P90 and G40.3- to the same newborn encounter.

P90 vs G40.3: Differentiating neonatal seizure codes

The P90 versus G40.3- distinction is one of the more frequently misapplied differentials in perinatal coding. G40.3- covers two conditions excluded from P90: benign myoclonic epilepsy in infancy and benign neonatal convulsions (familial). Both P90 and G40.3- describe convulsions in a newborn, but they arise from fundamentally different etiologies and cannot coexist on the same claim under the Excludes1 rule.

When origin is ambiguous, the coder should query the attending physician rather than assume a familial etiology. Upcoding to G40.3- on clinical suspicion alone, without documentation support, is a coding compliance risk. For a broader view of neonatal and perinatal neurology coding, the AAPC ICD-10-CM code browser provides full G40 subcode breakdowns alongside P90 perinatal codes.

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Related ICD-10 codes in the P90-P96 block

ICD-10 Code P90 is the first code in the P90-P96 block. Coders working in neonatal and perinatal settings should be familiar with all sibling codes in this block, as conditions like cerebral status disturbance (P91) or feeding problems (P92) frequently co-occur with convulsions and may need to be reported alongside P90.

Accurate capture of co-occurring conditions is critical for complete DRG and billing assignment in neonatal inpatient cases, alongside newborn care codes like 99460.

Clinical background: Neonatal convulsions

Neonatal convulsions coded under P90 are seizures occurring in newborns during the perinatal period, generally defined as before birth through the 28th day following birth. They represent one of the most common neurological emergencies that neonatology and OB-GYN practice teams manage in newborn care.

Unlike seizures in older children and adults, neonatal seizures often have identifiable acute causes: hypoxic-ischemic encephalopathy, electrolyte disturbances such as E16.1 or hypocalcemia, intracranial hemorrhage, meningitis, or structural brain anomalies.

Maternal substance exposure is another documented cause, and an H0001 assessment can help confirm it.

The distinction from benign familial neonatal convulsions (G40.3-) carries clinical weight beyond the paperwork, pointing to a different prognosis and treatment pathway. Perinatal convulsions coded P90 typically require investigation of the underlying cause and may indicate acute neonatal brain injury, occasionally requiring transfer under A0426 to a higher level of neonatal care.

Infection is one of the acute causes coders should watch for in the chart, alongside the hypoxic and metabolic causes already noted; see this meningitis care plan template for how that documentation is typically structured. Accurate coding of P90 helps neonatal units track case complexity and supports appropriate DRG assignment for resource-intensive neonatal stays.

Documentation requirements for assigning ICD-10 Code P90

P90 is a billable code, but billability does not mean it can be assigned without clinical support. According to the ICD-10-CM Official Guidelines for Coding and Reporting maintained by NCHS and CMS, perinatal diagnoses require physician documentation in the medical record.

The following elements should appear before P90 is assigned to a newborn inpatient claim. Structured clinical forms that capture these fields at admission reduce query burden later.

• Physician attestation: The attending or neonatologist must document convulsions or seizures explicitly in the medical record (progress notes, admission history, discharge summary, or problem list).
• Age confirmation: Documentation must support that the patient is within the perinatal period (before birth through the 28th day following birth). P90 does not apply to seizures diagnosed after day 28.
• Etiology note (or absence of familial basis): If an etiology is identified (hypoxia, metabolic, infectious), document it. If etiology is unknown, the absence of familial history should be noted to support P90 rather than G40.3-.
• No genetic/familial attribution: Confirm the record contains no language indicating KCNQ2/KCNQ3 mutation, family history of benign neonatal seizures, or a diagnosis of self-limited familial neonatal epilepsy.
• Clinical findings: EEG findings, imaging results, or clinical observation notes that describe seizure activity should be present, though specific thresholds vary by institution and specialist protocol.

When documentation is ambiguous, query the physician before assigning. Coders who assign P90 without adequate documentation risk a coding compliance finding on audit. Pabau’s structured clinical record tools help care teams capture the specific data points that support accurate ICD-10 code assignment at discharge.

Billing and MS-DRG mapping for ICD-10 Code P90

When P90 is assigned as the principal diagnosis on a Medicare or Medicaid inpatient claim, it maps to specific MS-DRGs through the CMS MS-DRG grouper. DRG assignment determines the fixed payment amount for an inpatient stay.

The specific MS-DRGs that P90 maps to depend on the MS-DRG version in effect for the fiscal year. Coders should verify the current DRG mapping using the CMS MS-DRG definitions manual for the applicable FY.

As a general reference, P90 as a neonatal neurological diagnosis typically groups within neonatal DRGs that account for complication and comorbidity (CC) or major complication and comorbidity (MCC) levels based on co-assigned codes, including prolonged ventilator support billed under E0466 after NICU discharge.

Properly capturing co-occurring conditions alongside P90, such as P91 for neonatal encephalopathy or codes for metabolic disturbances, can affect the DRG tier and therefore the reimbursement level. Pabau’s claims management software helps practice teams organize diagnosis code sets so that all relevant codes are captured before claim submission, reducing the risk of DRG downcoding.

Practices managing neonatal billing workflows can also explore digital clinical forms that pre-populate diagnosis fields from structured data captured at the point of care.

Present on admission (POA) reporting for P90

P90 is POA-exempt. It is not subject to Present on Admission (POA) indicator reporting on inpatient claims submitted to Medicare and Medicaid.

CMS treats the entire perinatal chapter (P00-P96) as exempt from POA reporting, since these conditions originate in the newborn. The present-on-admission concept was built to separate pre-existing conditions from hospital-acquired ones, a distinction that doesn’t apply to a diagnosis captured at or shortly after birth.

CMS publishes an annual list of POA-exempt diagnosis codes that includes the full P00-P96 perinatal chapter, so coders should not append a Y, N, W, or U indicator to P90 on the UB-04 or 837I claim. Billing software that flags P90 for a missing POA value is applying an outdated edit and should be reconfigured to reflect the exemption.

Because P90 sits within an exempt chapter, hospitals don’t need to make a payer-specific judgment call for this code the way they might for conditions outside the perinatal chapter. It’s still worth confirming the exemption annually against the current CMS POA-exempt list, since chapter groupings and exemption rules can shift between fiscal years.

The bottom line on P90 coding

Neonatal seizure coding hinges on one documentation question: is there a documented familial or genetic basis? When the record is silent on etiology or points to a perinatal cause, ICD-10 Code P90 is the correct assignment.

When KCNQ2/KCNQ3 mutation, a family history of benign neonatal convulsions, or a diagnosis of benign myoclonic epilepsy in infancy is confirmed, route to G40.3- instead. Getting this decision right protects reimbursement, reduces audit exposure, and reflects the clinical complexity of neonatal care.

Pabau’s patient care management tools help neonatal and pediatric teams structure clinical documentation at the point of care so that the diagnosis information needed for accurate ICD-10 code assignment is captured before discharge. To see how Pabau supports coding workflows from documentation through claim submission, book a demo.

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