Bonni S. Massa, MD

Medicare activity in 2024

Official CMS public-use data for Bonni S. Massa, 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.

Most frequent services

1. Cervical or vaginal cancer screening; pelvic and clinical breast examination (G0101)39 services
2. Established patient office or other outpatient visit with moderate level of decision making, if using time, 30 minutes or more (99214)33 services
3. Colorectal cancer screening; fecal occult blood test, immunoassay, 1-3 simultaneous (G0328)31 services
4. Screening papanicolaou smear; obtaining, preparing and conveyance of cervical or vaginal smear to laboratory (Q0091)19 services
5. Established patient office or other outpatient visit with low level od decision making, if using time, 20 minutes or more (99213)14 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%
• Arthritis52%
• High blood pressure46%
• Osteoporosis29%
• Anxiety20%
• Asthma19%

Hospitals where Bonni S. Massa works

Medicare's Facility Affiliation Data lists Bonni S. Massa 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.

• California Pacific Medical Center- Van Ness CampusSan Francisco, CA · Acute Care Hospital · Medicare rating: 3 of 5 stars · Emergency services: listed by Medicare · CCN 050047
• Marinhealth Medical CenterGreenbrae, CA · Acute Care Hospital · Medicare rating: 5 of 5 stars · Emergency services: listed by Medicare · CCN 050360
• Sonoma Valley HospitalSonoma, CA · Acute Care Hospital · Medicare rating: 2 of 5 stars · Emergency services: listed by Medicare · CCN 050090

Practice locations

Addresses where Bonni S. Massa is enrolled with Medicare (CMS data updated October 2, 2026).

• 505 Parnassus AveSan Francisco, CA 94143 (415) 476‑1000

Group practices

Medicare enrollment lists Bonni S. Massa as a member of this group (CMS data updated October 2, 2026).

• Regents Univ of California UCSF283 clinicians in the group

Specialties

• Obstetrics/Gynecologyprimary

Find other Obstetrics/Gynecology doctors in California →

Other OB-GYNs in San Francisco

Clinicians with the same Medicare primary specialty in San Francisco, CA — not a recommendation.

• Yue Song, MD
• Aleksandar Rajkovic, MD
• Katherine L. Gregory, MD
• Carolyn J. Mannon, MD
• Daniella Rogerson, MD
• Anna Rabinov, MD
• Joanne Kim
• Amita Kachru, MD

All OB-GYNs in San Francisco →

Other clinicians in Regents Univ of California UCSF

Medicare enrollment lists these clinicians in the same group practice — not a recommendation.

• Lia Wystrach, NP
• Loretta M. Alimam, NP
• Been Liao, MD
• Edward Alfrey, MD
• Katerina A. Zappas-Levy, MD
• Mary E. Wilkosz, NP

Clinician information

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

1. Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated October 2, 2026, retrieved October 29, 2026
2. Hospital General Information — CMS, data updated October 26, 2026, retrieved November 13, 2026
3. National Downloadable File (Doctors and Clinicians) — CMS, data updated October 2, 2026, retrieved October 29, 2026
4. Medicare Physician & Other Practitioners - by Provider — CMS, data year 2024, released May 21, 2026; Medicare Physician & Other Practitioners - by Provider and Service
5. NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
6. Medicare Care Compare — official Medicare tool to look up clinicians