Quick answers
- Does Alyssa M. Grossen accept Medicare assignment?
- Yes. Medicare's clinician data says Alyssa M. Grossen accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of October 2, 2026. Ask the office to confirm before your visit.
- What is Alyssa M. Grossen's NPI number?
- 1912498411. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Alyssa M. Grossen works
Medicare's Facility Affiliation Data lists Alyssa M. Grossen at these hospitals (updated October 2, 2026). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians. Star rating and emergency services: Hospital General Information (CMS), data updated October 26, 2026.
- Yale-New Haven HospitalNew Haven, CT · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 070022
Practice locations
Addresses where Alyssa M. Grossen is enrolled with Medicare (CMS data updated October 2, 2026).
- 20 York StNew Haven, CT 06510 (203) 688‑4242
Group practices
Medicare enrollment lists Alyssa M. Grossen as a member of this group (CMS data updated October 2, 2026).
- Yale University2,645 clinicians in the group
Specialties
- Gastroenterologyprimary
- Internal Medicinealso
Other gastroenterologists in New Haven
Clinicians with the same Medicare primary specialty in New Haven, CT — not a recommendation.
Other clinicians in Yale University
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Oklahoma College Of Medicine |
| Graduation year | 2018 (8 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1912498411 |
| 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 October 2, 2026, retrieved October 29, 2026
- Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
- National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
- 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