Quick answers
- Which hospitals does Gary D. Koenig work at?
- Medicare's official clinician data lists Gary D. Koenig at 3 hospitals: Barnes-Jewish St Peters Hospital, Mercy Hospital Washington and Progress West Hospital. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Gary D. Koenig see patients?
- Medicare's clinician data lists 3 practice locations, including Saint Peters, MO, O Fallon, MO and Washington, MO. Call before your visit to confirm the address.
- What is Gary D. Koenig's specialty?
- Medicare lists Gastroenterology as the primary specialty, and also Internal Medicine.
- Does Gary D. Koenig accept Medicare assignment?
- Yes. Medicare's clinician data says Gary D. Koenig accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Gary D. Koenig?
- (636) 916-7272, as listed in official Medicare / NPI Registry data.
- What is Gary D. Koenig's NPI number?
- 1861485724. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Gary D. Koenig works
Medicare's Facility Affiliation Data lists Gary D. Koenig at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Barnes-Jewish St Peters HospitalSaint Peters, MO · Acute Care Hospital · CCN 260191
- Mercy Hospital WashingtonWashington, MO · Acute Care Hospital · CCN 260052
- Progress West HospitalOfallon, MO · Acute Care Hospital · CCN 260219
Practice locations
Addresses where Gary D. Koenig is enrolled with Medicare (CMS data updated 2026-10-02).
- 10 Hospital Dr, Suite 100Saint Peters, MO 63376 (636) 916‑7272
- 2630 Hwy KO Fallon, MO 63368 (636) 240‑5454
- 901 Patients 1st Dr, Suite 3300Washington, MO 63090 (636) 239‑7344
Group practices
Medicare enrollment lists Gary D. Koenig as a member of these groups (CMS data updated 2026-10-02).
- Physician Groups LC521 clinicians in the group
- Mercy Clinic Gastroenterology LLC67 clinicians in the group
Specialties
- Gastroenterologyprimary
- Internal Medicinealso
Other gastroenterologists in Saint Peters
Clinicians with the same Medicare primary specialty in Saint Peters, MO — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Saint Louis University School Of Medicine |
| Graduation year | 1986 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1861485724 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians