Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Aaron Patrick Fieker, DO

Individual provider Gastroenterology Physician · NPI 1326268079

Aaron Patrick Fieker, DO practises Gastroenterology in Tulsa, Oklahoma. Graduated from Oklahoma State University College of Osteopathic Medicine in 2005, 21 years ago. Practices with Gastroenterology Specialists, Inc, a 22-clinician group, accepts Medicare assignment and offers telehealth. Licensed in Oklahoma.

Years since qualifying
21
Trained at
Oklahoma State University College of Osteopathic Medicine
Licensed in
OK
In the registry since
2007
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

10210 E 91st St
Tulsa, OK 74133-5834
Phone: (918) 940-8500
Show map & directions

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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Gastroenterology Physician (primary) Taxonomy 207RG0100X · Licence 4758 (OK)

Record details

NPI number1326268079
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedApril 26, 2007
Last updated in NPPESMay 22, 2025
Certification dateMay 22, 2025

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyGASTROENTEROLOGY
Medical schoolOKLAHOMA STATE UNIVERSITY COLLEGE OF OSTEOPATHIC MEDICINE
Graduated 2005 (21 years in practice)
Group practice Gastroenterology Specialists, Inc. — 22 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations3 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Upper gastrointestinal (GI) endoscopy for acid reflux 172 times · 88th percentile
Colonoscopy 106 times · 81st percentile

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients665
Services billed 1,159 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $2,108 112 payments · a meal or drink at a meeting or visit, not a fee

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician. Those with a page here are linked.

Colleagues at Gastroenterology Specialists, Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 22 clinicians in the practice; 12 are shown here.

Other providers in Tulsa