Michael Ansstas, M.D.
NPI 1851658728 · Gastroenterology Physician · Saint Louis, MO
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Michael Ansstas, M.D. is a Gastroenterology Physician provider in Saint Louis, MO (NPI 1851658728).
Provider details
- NPI number
- 1851658728
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- 036153515 (IL)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
14 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
3 documented practice locations
- Medicare service volume (vs. specialty peers)25% of score
504 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) |
|---|---|---|
| Biopsy of Esophagus, Stomach, And/Or Upper Small Bowel Using a Flexible Endoscope43239 | 101 | $79 |
| Removal of Polyps Or Growths of Large Bowel Using an Endoscope With Mechanical Snare45385 | 72 | $228 |
| Subsequent Hospital Care With Moderate Levelof Medical Decision Making, If Using Time, at Least 35 Minutes99232 | 60 | $75 |
| Biopsy of Large Bowel Using a Flexible Endoscope45380 | 49 | $110 |
| Initial Hospital Care With Straightforward Or Low-Level Medical Decision Making, If Using Time, at Least 55 Minutes99222 | 36 | $124 |
| Initial Hospital Care With Moderate Level of Medical Decision Making, If Using Time, at Least 75 Minutes |
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 |
|---|---|---|
| Pantoprazole Sodium | 163 | 80 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 55 | 51 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Peg-3350 and Electrolytes | 33 | 32 |
| Sodium, Potassium,mag Sulfatesbrand: Sod Sulf-Potass Sulf-Mag Sulf | 17 | 17 |
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.
$239 across 4 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
Additional practice locations (2)
- 4 Memorial Dr Ste 230bAlton, IL 62002-6705Phone: (618) 463-7874
- 3 Saint Elizabeth BlvdO Fallon, IL 62269-1281Phone: (618) 641-5803Fax: (618) 607-5116
Registry dates
- Enumerated
- 2012-04-17
- Last updated
- 2025-10-27
- Certified
- 2025-10-27
Frequently asked questions
- What is Michael Ansstas's NPI number?
- Michael Ansstas's National Provider Identifier (NPI) is 1851658728, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Michael Ansstas's specialty?
- Michael Ansstas is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is Michael Ansstas located?
- Michael Ansstas's practice location on file with NPPES is 11155 Dunn Rd Ste 309e, Saint Louis, MO 63136-6111.
- What is Michael Ansstas's phone number?
- The practice phone number listed in the NPPES registry for Michael Ansstas is (314) 953-8799.
- Does Michael Ansstas accept Medicare?
- Michael Ansstas is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Michael Ansstas's NPI active?
- Yes — Michael Ansstas's NPI (1851658728) is active in the NPPES registry as of the last update on 2025-10-27.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.