William Oh, M.D.
NPI 1598100323 · Colon & Rectal Surgery Physician · Irvine, CA
Enrolled with Medicare as Practitioner - Colorectal Surgery (proctology) · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Oh, M.D. is a Colon & Rectal Surgery Physician provider in Irvine, CA (NPI 1598100323).
Provider details
- NPI number
- 1598100323
- Entity type
- Individual
- Primary specialty
- Colon & Rectal Surgery PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- A136780 (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
13 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
146 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) |
|---|---|---|
| New Patient Office Or Other Outpatient Visit With a High Level of Medical Decision Making, If Using Time, 60 Minutes Or More99205 | 56 | $185 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 31 | $81 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes99223 | 17 | $179 |
| Established Patient Office Or Other Outpatient Visit With Low Level OD Decision Making, If Using Time, 20 Minutes Or More99213 | 16 | $69 |
| Diagnostic Exam of Anus Using an Endoscope46600 | 14 | $44 |
| New Patient Office Or Other Outpatient Visit With Moderate Level of Medical Decision Making, If Using Time, 45 Minutes Or More99204 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 4 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Oxycodone Hcl | 19 | 17 |
| Metronidazole | 15 | 13 |
| Amoxicillin/Potassium Clavbrand: Amoxicillin-Clavulanate Potass | 14 | — |
| Neomycin Sulfate | 12 | 12 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means no Part D record, never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$134 across 5 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
- 2013-05-07
- Last updated
- 2026-05-07
- Certified
- 2026-05-07
Frequently asked questions
- What is William Oh's NPI number?
- William Oh's National Provider Identifier (NPI) is 1598100323, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Oh's specialty?
- William Oh is listed in the NPPES registry with a primary specialty of Colon & Rectal Surgery Physician (Allopathic & Osteopathic Physicians).
- Where is William Oh located?
- William Oh's practice location on file with NPPES is 16405 Sand Canyon Ave Ste 280, Irvine, CA 92618-3792.
- What is William Oh's phone number?
- The practice phone number listed in the NPPES registry for William Oh is (949) 557-0370.
- Does William Oh accept Medicare?
- William Oh is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Oh's NPI active?
- Yes — William Oh's NPI (1598100323) is active in the NPPES registry as of the last update on 2026-05-07.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.