Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

Ann M Chen, MD

Individual provider Gastroenterology Physician · NPI 1003840307

Ann M Chen, MD practises Gastroenterology in Stanford, California. Graduated from Albert Einstein College of Medicine of Yeshiva University in 2000, 26 years ago. Practices with County of Santa Clara, a 993-clinician group, accepts Medicare assignment and offers telehealth. Licensed in California.

Years since qualifying
26
Trained at
Albert Einstein College of Medicine of Yeshiva University
Licensed in
CA
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

300 Pasteur Dr A149 MC5202
Stanford, CA 94305-2200 Not confirmed with CMS for 17 years — call before visiting
Phone: (650) 725-3376
Fax: (650) 723-8305
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Gastroenterology Physician (primary) Taxonomy 207RG0100X · Licence A76890 (CA)

Record details

NPI number1003840307
Entity typeIndividual (Type 1)
GenderFemale
Credentials MD
Sole proprietorNo
NPI enumeratedJuly 10, 2006
Last updated in NPPESJanuary 10, 2009

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyGASTROENTEROLOGY
Medical schoolALBERT EINSTEIN COLLEGE OF MEDICINE OF YESHIVA UNIVERSITY
Graduated 2000 (26 years in practice)
Group practice County Of Santa Clara — 993 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
TelehealthOffers telehealth services
Practice locations2 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Colonoscopy 76 times · 73rd percentile
Upper gastrointestinal (GI) endoscopy for acid reflux 46 times · 62nd percentile

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients112
Services billed 188 a service is one billed item, such as a visit, a test or a procedure
Average patient age72

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at County of Santa Clara

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 993 clinicians in the practice; 12 are shown here.

Other providers in Stanford