Marissa Grillo, PA-C
NPI 1629650635 · Physician Assistant · Stanford, CA
Enrolled with Medicare as Practitioner - Physician Assistant · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Marissa Grillo, PA-C is a Physician Assistant provider in Stanford, CA (NPI 1629650635).
Provider details
- NPI number
- 1629650635
- Entity type
- Individual
- Primary specialty
- Physician AssistantPhysician Assistants & Advanced Practice Nursing Providers
- Credential
- PA-C
- Sex
- Female
- Sole proprietor
- No
- License
- 61043 (CA)
Specialties & taxonomies
Physician Assistants & Advanced Practice Nursing Providers
Physician Assistants & Advanced Practice Nursing Providers
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure28% of score
5 yrs in NPPES registry
- Profile completeness28% of score
100% of core fields populated
- Practice footprint17% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)28% of score
16 Medicare services, 2024 (ranked within specialty)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Critical Care, First 30-74 Minutes99291 | 16 | $198 |
Typical Medicare-allowed amounts for these services range $198–$198 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
Practice location
Mailing address
Registry dates
- Enumerated
- 2021-04-28
- Last updated
- 2025-10-29
- Certified
- 2025-10-29
Frequently asked questions
- What is Marissa Grillo's NPI number?
- Marissa Grillo's National Provider Identifier (NPI) is 1629650635, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Marissa Grillo's specialty?
- Marissa Grillo is listed in the NPPES registry with a primary specialty of Physician Assistant (Physician Assistants & Advanced Practice Nursing Providers).
- Where is Marissa Grillo located?
- Marissa Grillo's practice location on file with NPPES is 300 Pasteur Dr, Stanford, CA 94305-2200.
- What is Marissa Grillo's phone number?
- The practice phone number listed in the NPPES registry for Marissa Grillo is (650) 723-4000.
- Does Marissa Grillo accept Medicare?
- Marissa Grillo is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Marissa Grillo's NPI active?
- Yes — Marissa Grillo's NPI (1629650635) is active in the NPPES registry as of the last update on 2025-10-29.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.