Doctor profile · Federal record
Dr. Ann Chen, MD
Gastroenterology Physician (CMS: Gastroenterology) · Stanford, CA
- NPI 1003840307
- Accepts Medicare
- MIPS 74.2 / 100 · 2023
- 26 yrs in practice
- Female
- Group practice
- No sanctions
Practice & contact
- Primary practice
-
300 Pasteur Dr, A149, Mc5202
Stanford, CA 943052200
(650) 725-3376
fax (650) 723-8305
Credentials & registration
- NPI registered
- July 2006 — 20 yrs on file
- Profile last updated
- January 10, 2009
- Year of graduation
- 2000 — 26 yrs since
- Specialty taxonomy
- 207RG0100X — NUCC code
- State license (1)
- California #A76890
Federal sanctions & exclusions
No sanctions, exclusions or revocations on file
Checked against OIG LEIE on NPI 1003840307. Last verified May 11, 2026.Medicare procedures · 2023
Top services delivered
Total services
234
Distinct HCPCS
9
Medicare allowed
$25,448
| HCPCS | Description | Services | Patients | Avg allowed | |
|---|---|---|---|---|---|
G0500 |
Moderate sedation services provided by the same physician or other qualified health care professional performing a gastrointestinal endoscopic service that sedation supports, requiring the presence of an independent trained observer to assist in the monito | 81 | 77 | $6 | |
99222 |
Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes | 33 | 31 | $149 | |
99214 |
Established patient office or other outpatient visit, 30-39 minutes | 29 | 28 | $113 | |
43235 |
Diagnostic exam of esophagus, stomach, and/or upper small bowel using a flexible endoscope | 22 | 22 | $125 | |
43242 |
Ultrasound guided needle aspiration or biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope | 17 | 17 | $292 | |
43239 |
Biopsy of esophagus, stomach, and/or upper small bowel using a flexible endoscope | 14 | 14 | $125 | |
45378 |
Diagnostic exam of large bowel using a flexible endoscope | 14 | 14 | $203 | |
45380 |
Biopsy of large bowel using a flexible endoscope | 13 | 13 | $213 | |
99204 |
New patient office or other outpatient visit, 45-59 minutes | 11 | 11 | $153 |
In context: peer comparison
Among 18 peers in Stanford Gastroenterology Physician, average services per provider: 46. This provider delivers 5.1× the peer median.Medicare Part D · 2023
Top prescriptions
Total claims
147
Patients
38
Total drug cost
$7,065
| Drug | Type | Claims | Patients | Total cost |
|---|---|---|---|---|
| Omeprazole | Generic | 46 | 0 | $560 |
| Peg-3350 and Electrolytes (Peg3350/Sod Sulf,Bicarb,Cl/Kcl) | Brand | 21 | 21 | $416 |
| Famotidine | Generic | 18 | 0 | $97 |
| Entecavir | Generic | 17 | 0 | $1,292 |
| Gavilyte-G (Peg3350/Sod Sulf,Bicarb,Cl/Kcl) | Brand | 17 | 17 | $325 |
| Tenofovir Disoproxil Fumarate | Generic | 15 | 0 | $3,992 |
| Pantoprazole Sodium | Generic | 13 | 0 | $383 |
Frequently asked questions
What is Dr. Ann Chen's medical specialty?
Dr. Ann Chen practices Gastroenterology Physician in Stanford, CA.
Where does Dr. Ann Chen practice?
Dr. Ann Chen practices at 300 Pasteur Dr, Stanford, CA 943052200. Office phone: 6507253376.
What is Dr. Ann Chen's NPI?
Dr. Ann Chen's National Provider Identifier (NPI) is 1003840307, issued by NPPES.
Does Dr. Ann Chen accept Medicare assignment?
Yes. Dr. Ann Chen accepts Medicare assignment, meaning Medicare-allowed amounts are accepted as full payment for covered services.
What procedures does Dr. Ann Chen commonly perform?
Top Medicare-reported procedures in 2023: Moderate sedation services provided by the same physician or other qualified health care professional performing a gastrointestinal endoscopic service that sedation supports, requiring the presence of an independent trained observer to assist in the monito (HCPCS G0500); Initial hospital care with straightforward or low-level medical decision making (HCPCS 99222); Established patient office or other outpatient visit (HCPCS 99214). Source: CMS Medicare Physician & Other Practitioners file.