NPI Portal NPI Lookup & Verification

Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Alyssa Marie Grossen, MD

Gastroenterology Physician in New Haven, CT · enumerated 2018.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1912498411

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)
Name Alyssa Marie Grossen
Credential MD
Sex Female
Practice address 20 York St, New Haven, CT, 06510
Phone (203) 688-4242
Enumeration date May 21, 2018
Last updated in NPPES Apr 8, 2025

Taxonomy & licenses

390200000X Student in an Organized Health Care Education/Training Program Student, Health Care Secondary
207RG0100X Gastroenterology Physician Allopathic & Osteopathic Physicians · License 80523 (CT) Primary
MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier Type State Issuer
207R00000X Medicaid OK -

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

Where does Alyssa Grossen practice?
The practice location on file with NPPES is in New Haven, CT. Providers can have multiple locations; NPPES lists the primary practice address.
What is the NPI number for Alyssa Grossen?
The National Provider Identifier (NPI) for Alyssa Grossen is 1912498411, a Type 1 (individual) record in the CMS NPPES registry.

Other providers at this practice address

Browse all →

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-04-08.