Quick answers
- Does Gillian L. Hsieh accept Medicare assignment?
- Yes. Medicare's clinician data says Gillian L. Hsieh 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.
- How many Medicare patients does Gillian L. Hsieh see?
- In 2024, CMS data shows 211 Original Medicare patients and 698 services for Gillian L. Hsieh. This counts Original Medicare only and measures volume, not quality.
- What is Gillian L. Hsieh's NPI number?
- 1063765576. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Medicare activity in 2024
Official CMS public-use data for Gillian L. Hsieh, data year 2024 (released May 21, 2026). It covers Original Medicare (fee-for-service) patients only, not Medicare Advantage or other insurance. It shows volume, not quality or outcomes. CMS hides any count of 10 or fewer patients.
| Original Medicare patients | 211 |
|---|---|
| Services billed to Medicare | 698 |
| Different services or procedures | 82 |
| Participating Medicare provider | Yes |
| Average age of these patients | 74 |
Most frequent services
- Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)104 services
- Established patient office or other outpatient visit with high level of medical decision making, if using time, 40 minutes or more (99215)96 services
- New patient office or other outpatient visit with a high level of medical decision making, if using time, 60 minutes or more (99205)70 services
- Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)54 services
- Imaging of lymph nodes during surgery (38900)38 services
Chronic conditions among these patients
Share of this clinician’s Original Medicare patients with each condition, as published by CMS (it describes the patients, not the care given).
- High cholesterol74%
- High blood pressure66%
- Cancer (breast, colorectal, lung, prostate, endometrial or leukemia/lymphoma)55%
- Arthritis36%
- Osteoporosis26%
- Diabetes25%
Hospitals where Gillian L. Hsieh works
Medicare's Facility Affiliation Data lists Gillian L. Hsieh 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.
- Community Hospital of the Monterey PeninsulaMonterey, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050145
- El Camino HealthMountain View, CA · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 050308
- Peninsula Medical CenterBurlingame, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050007
- Sutter Maternity & Surgery Center of Santa CruzSanta Cruz, CA · Acute Care Hospital · Emergency services: not listed by Medicare · CCN 050714
Practice locations
Addresses where Gillian L. Hsieh is enrolled with Medicare (CMS data updated October 2, 2026).
- 2490 Hospital Dr, Suite 109Mountain View, CA 94040 (650) 853‑5745
Group practices
Medicare enrollment lists Gillian L. Hsieh as a member of this group (CMS data updated October 2, 2026).
- Sutter Bay Medical Foundation3,829 clinicians in the group
Specialties
- Gynecological Oncologyprimary
- Obstetrics/Gynecologyalso
Other gynecologic oncologists in California
Clinicians with the same Medicare primary specialty in California — not a recommendation.
Other clinicians in Sutter Bay Medical Foundation
Medicare enrollment lists these clinicians in the same group practice — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | Baylor College Of Medicine |
| Graduation year | 2011 (15 years since medical school) |
| Gender (as listed) | Female |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1063765576 |
| 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
- Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
- 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