NPI registry status
Active
2026 NPPES data Obstetrics & Gynecology Physician NPI 1689668881 MD
Verify on CMS → Roger Williamson, MD
Obstetrics & Gynecology Physician in Iowa City, Iowa.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 44,326 in Obstetrics & Gynecology Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration, see our methodology.
Federal data, no proprietary rating.
We show these CMS records as-is - no composite score, no star rating, no editorial opinion layered on top.
What the federal data shows
Roger Williamson, MD is an Obstetrics & Gynecology Physician in Iowa City, Iowa, listed in the federal CMS National Provider Identifier registry.
- #34
- Obstetrics & Gynecology Physician rank among Iowa specialties
Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) - no proprietary rating or editorial opinion is applied.
Federal trust snapshot
What official records show about Roger Williamson, MD
Bare NPI registry listing — limited federal enrichment beyond basic enumeration. Verify all credentials with official sources.
- Verified
NPI registry status
Active listing in the CMS National Provider Identifier Registry (NPI 1689668881), first enumerated 09/02/2005.
Source: CMS NPPES
- Not in federal data
Medicare Part D participation
No 2023 Medicare Part D prescribing volume appears in the CMS public file for this NPI (may reflect specialty, new enrollment, or non-prescribing role).
Source: CMS Part D Prescriber PUF
- Reported
Board certification signal
Practices in an ABMS-board-eligible specialty; board certification not confirmed in federal records.
- Not in federal data
Individual sanction lookup
PlainDoctor does not publish per-provider disciplinary determinations. Confirm current license and any individual actions through the state medical board or FSMB verification service.
Source: State medical board / FSMB
This trust snapshot summarizes only what appears in federal CMS/NPPES public records. It is not a composite score, star rating, patient review, or clinical recommendation. PlainDoctor never fabricates reviews or AggregateRating schema.
CMS NPPES provider registry desk
NPI 1689668881 · Obstetrics & Gynecology Physician
NPI-10 · ENUM-LEGACY · TAX-MID · RX-NONE · BOOK-THIN · PHOTO-ENUM
- NPI-10 1689668881
- ENUM-LEGACY 2005
- TAX-MID 44K Obstetrics &
- RX-NONE No Part D
- BOOK-THIN 334 in Iowa
- PHOTO-ENUM Dionne Rouselle · 2005
◑
Board-eligible specialty (heuristic, not verified)
Roger Williamson, MD practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).
What does the federal data show about Roger Williamson, MD?
Quality data not reportedPrimary specialty
Obstetrics & Gynecology Physician
Specialty distribution in Iowa
How Obstetrics & Gynecology Physician compares to other specialties among Iowa providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Obstetrics & Gynecology Physician. Verify directly:
How MIPS and board certification work
The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.
Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).
Practice Address
Provider Details
| NPI | 1689668881 |
|---|---|
| Specialty | Obstetrics & Gynecology Physician |
| Credentials | MD |
| Gender | Male |
| NPI Issued | 09/02/2005 |
Obstetrics & Gynecology Physician Overview
How Roger Williamson, MD fits within the Obstetrics & Gynecology Physician landscape nationally.
44,326
Obstetrics & Gynecology Physician Providers in US
56
States with Obstetrics & Gynecology Physician
179
Avg Claims per Provider
Nationwide Obstetrics & Gynecology Physician peers with similar MIPS or enrollment year
Two federal-record peer sets for Williamson, both outside Iowa so the neighborhoods are not geographic containment.
Same NPPES enumeration year (2005)
Same-specialty clinicians who entered the NPI registry in the same calendar year, outside this state.
Nearby Obstetrics & Gynecology Physician Providers in Iowa
Other clinicians with the same primary specialty enrolled in Iowa, drawn from the same CMS NPPES roster as Williamson.
One of 334 Obstetrics & Gynecology Physician providers enrolled in Iowa, 5 are shown here.
Dr. Johanna Abernathy
MD
Cedar Rapids, IA
Dr. Diane Adam
M.D.
Coralville, IA
Dr. Angela Aldrich
M.D.
Sioux City, IA
Dr. Anisa Alizaidy
MD
Iowa City, IA
Dr. Olanike Alonge-Obe
MD, MPH
Waterloo, IA
Compare Obstetrics & Gynecology Physician nationally: see state-by-state distribution →
Frequently Asked Questions
What is Roger Williamson, MD's specialty? ▼
Roger Williamson, MD specializes in Obstetrics & Gynecology Physician and practices in Iowa City, Iowa. Credentials: MD.
Where is Roger Williamson, MD located? ▼
Roger Williamson, MD is located at 200 HAWKINS DR, Iowa City, IA, 52242. Phone: (319) 356-4119.
What is Roger Williamson, MD's NPI number? ▼
Roger Williamson, MD's National Provider Identifier (NPI) is 1689668881, issued on 09/02/2005.
How many Obstetrics & Gynecology Physician providers are there in the US? ▼
There are 44,326 Obstetrics & Gynecology Physician providers across 56 states in the US. The average Obstetrics & Gynecology Physician provider writes 179 Medicare Part D claims per year.
Does Roger Williamson, MD accept Medicare? ▼
Roger Williamson, MD appears in CMS Medicare data. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Roger Williamson, MD's credentials? ▼
Roger Williamson, MD's NPI is 1689668881 with credentials MD. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.
Data Sources
View source datasets and methodology notes
- Provider Directory
- CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
- Specialty Classification
- NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
- Limitations
- Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.
See our complete data methodology for details on how we collect and process government data.
Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).
Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.