KAREN E O'BRIEN M.D.
NPI 1780623215
Obstetrics & Gynecology - Maternal & Fetal Medicine in South Weymouth, MA
About Karen E O'brien M.d. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
KAREN E O'BRIEN M.D. (NPI 1780623215) is an individual maternal & fetal medicine provider in South Weymouth, Massachusetts, licensed in Massachusetts (218797) and active in the NPI registry since June 2006. She is enrolled in Medicare PECOS, is affiliated with South Shore Hospital, and maintains 2 additional practice locations.
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Locations 2
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
Karen E O'brien M.d. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Medicare Billing Reassignments
4Medicare enrollment records show Karen O'brien reassigns Medicare billing to 4 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Weymouth, MA 02190
- Reassigned Medicare billing, Massachusetts enrollment
- 671 clinicians in this Medicare group
Norwell, MA 02061
- Reassigned Medicare billing, Massachusetts enrollment
- 346 clinicians in this Medicare group
Boston, MA 02215
- Reassigned Medicare billing, Massachusetts enrollment
- 1,477 clinicians in this Medicare group
Boston, MA 02215
- Reassigned Medicare billing, Massachusetts enrollment
- Also billed through NPI 1518908136 (Massachusetts)
- 2,579 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
South Shore Hospital
Acute Care Hospitals · South Weymouth, MAPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 02190 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 20
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
WEYMOUTH, MA 02190
SOUTH WEYMOUTH, MA 02190
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Karen O'brien's NPI number?
The NPI number for Karen O'brien is 1780623215. It was assigned to this individual provider in the NPPES registry on June 6, 2006.
Where is Karen O'brien located?
Karen O'brien practices at 55 Fogg Rd, South Weymouth, MA 02190. The listed phone number is (781) 624-8000.
What is Karen O'brien's specialty?
The primary specialty registered for this NPI is Obstetrics & Gynecology, specializing in Maternal & Fetal Medicine, with taxonomy code 207VM0101X.
Is Karen O'brien enrolled in Medicare?
Yes. Karen O'brien is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Which organizations bill Medicare for Karen O'brien's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Karen O'brien reassigns Medicare benefits to 4 organizations: Coastal Medical Associates (Weymouth, MA), South Shore Medical Center, Inc. (Norwell, MA), Beth Israel Deaconess Medical Center, Inc. (Boston, MA) and Harvard Medical Faculty Phys At Beth Israel Deaconess Med Ctr Inc (Boston, MA). Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Karen O'brien's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
Is Karen O'brien affiliated with any hospitals?
According to CMS data, Karen O'brien is affiliated with South Shore Hospital.
When was this NPI record last updated?
The NPPES record for Karen O'brien was last updated on October 19, 2023. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 3 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Karen E O'brien, M.D. · NPI 1780623215
Maternal & Fetal Medicine physician in South Weymouth, Massachusetts. Individual provider, active in the CMS NPPES registry since June 6, 2006.
## Identity
- **NPI:** 1780623215 (Entity type: Individual)
- **Enumerated:** June 6, 2006
- **Primary specialty:** Obstetrics & Gynecology - Maternal & Fetal Medicine · taxonomy 207VM0101X
- **State license:** 218797 (Massachusetts)
- **Sole proprietor:** No
## Practice location
- **Address:** 55 FOGG RD, South Weymouth, MA 02190-2432
- **Phone:** (781) 624-8000
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 4 organizations under Medicare reassignment (form CMS-855R): Coastal Medical Associates (NPI 1932175684, Weymouth, MA); South Shore Medical Center, Inc. (NPI 1669411856, Norwell, MA); Beth Israel Deaconess Medical Center, Inc. (NPI 1548202641, Boston, MA); Harvard Medical Faculty Phys At Beth Israel Deaconess Med Ctr Inc (NPI 1194765438, Boston, MA) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Georgetown University School Of Medicine, class of 1996
## Record status
- **NPPES last updated:** October 19, 2023
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Source: [NPI Profile](https://npiprofile.com/npi/1780623215) · Data from the CMS NPPES public registry.