Quick answers
- Which hospitals does Youssef Assioun work at?
- Medicare's official clinician data lists Youssef Assioun at 3 hospitals: Mercy Hospital Jefferson, Mercy Hospital South and Mercy Hospital St Louis. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Youssef Assioun see patients?
- Medicare's clinician data lists 2 practice locations, including Saint Louis, MO and Lake St Louis, MO. Call before your visit to confirm the address.
- What is Youssef Assioun's specialty?
- Medicare lists Gastroenterology as the primary specialty.
- Does Youssef Assioun accept Medicare assignment?
- Yes. Medicare's clinician data says Youssef Assioun 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 Youssef Assioun?
- (636) 561-9020, as listed in official Medicare / NPI Registry data.
- What is Youssef Assioun's NPI number?
- 1639370919. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Youssef Assioun works
Medicare's Facility Affiliation Data lists Youssef Assioun at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Mercy Hospital JeffersonCrystal City, MO · Acute Care Hospital · CCN 260023
- Mercy Hospital SouthSaint Louis, MO · Acute Care Hospital · CCN 260077
- Mercy Hospital St LouisSaint Louis, MO · Acute Care Hospital · CCN 260020
Practice locations
Addresses where Youssef Assioun is enrolled with Medicare (CMS data updated 2026-10-02).
- 10012 Kennerly Rd, Suite 102Saint Louis, MO 63128
- 200 Brevco Plz, Suite 208Lake St Louis, MO 63367 (636) 561‑9020
Group practices
Medicare enrollment lists Youssef Assioun as a member of this group (CMS data updated 2026-10-02).
- Mercy Clinic Gastroenterology LLC67 clinicians in the group
Specialties
- Gastroenterologyprimary
Other gastroenterologists in Saint Louis
Clinicians with the same Medicare primary specialty in Saint Louis, MO — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Graduation year | 2003 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1639370919 |
| 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