John Armstrong, MD
NPI 1790875995 · Gynecology Physician · Napa, CA
Enrolled with Medicare as Practitioner - Obstetrics/Gynecology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Armstrong, MD is a Gynecology Physician provider in Napa, CA (NPI 1790875995).
Provider details
- NPI number
- 1790875995
- Entity type
- Individual
- Primary specialty
- Gynecology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- 00C378990 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
1,804 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
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 .
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) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 413 | $145 |
| Exam of External Female Genitals Using an Endoscope56820 | 183 | $108 |
| Complete Ultrasound Scan of 1 Breast76641 | 180 | $120 |
| Ultrasound Scan of Uterus, Ovaries, Tubes, Cervix and Pelvic Area Through Vagina76830 | 175 | $145 |
| Annual Depression Screening, 5 to 15 MinutesG0444 | 135 | $22 |
| Established Patient Office Or Other Outpatient Visit With High Level of Medical Decision Making, If Using Time, 40 Minutes Or More99215 | 129 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 12 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Estradiol | 257 | 81 |
| Progesterone, Micronizedbrand: Progesterone | 57 | 17 |
| Terconazole | 39 | 20 |
| Nitrofurantoin Monohyd/M-Crystbrand: Nitrofurantoin Mono-Macro | 36 | 16 |
| Estradiolbrand: Estradiol (twice Weekly) | 24 | — |
| Estradiolbrand: Yuvafem | 23 | — |
| Estrogens, Conjugatedbrand: Premarin | 16 |
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$159 across 8 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-10-16
- Last updated
- 2007-07-08
Frequently asked questions
- What is John Armstrong's NPI number?
- John Armstrong's National Provider Identifier (NPI) is 1790875995, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Armstrong's specialty?
- John Armstrong is listed in the NPPES registry with a primary specialty of Gynecology Physician (Allopathic & Osteopathic Physicians).
- Where is John Armstrong located?
- John Armstrong's practice location on file with NPPES is 3434 Villa Ln, Napa, CA 94558.
- What is John Armstrong's phone number?
- The practice phone number listed in the NPPES registry for John Armstrong is (707) 257-4317.
- Does John Armstrong accept Medicare?
- John Armstrong is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Armstrong's NPI active?
- Yes — John Armstrong's NPI (1790875995) is active in the NPPES registry as of the last update on 2007-07-08.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.