DR. WILLIAM JAMES GIESEN (M.D.) – Internal Medicine Physician, NPI 1124104724
Internal Medicine Physician
Main info
Doctor Profile
Profile Insights
NPPES metrics only — not quality of care.
3,448 INTERNAL MEDICINE in CT
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Provider Addresses for DR. WILLIAM JAMES GIESEN (M.D.)
1500, Post Road, Noroton, Darien, Fairfield County, Connecticut, 06820, United States
DARIEN, CT 06820
Phone: (203) 655-2516
Fax: (203) 656-3665
Type: Mailing
1500, Post Road, Tokeneke, Noroton, Darien, Western Connecticut Planning Region, Connecticut, 06820, United States
DARIEN, CT 06820
Phone: (203) 655-2516
Fax: (203) 656-3665
Type: Location
NPPES updates history
No NPPES updates recorded for this provider.
Prescription Activity
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Open Payments (CMS)
No Open Payments data available for this provider.
This can happen when there are no reportable CMS Open Payments records.
Medicare Enrollment & Revalidation
Source: CMS public data · Not endorsed by CMS ·
Educational use only—not medical, billing, or legal advice.
PECOS enrollment status
Participating (accepts Medicare assignment)
Enrollment effective: 2003-12-03
PECOS data refreshed: 2026-05-27
Medicare revalidation (CMS due date list)
Due date not assigned yet
CMS is tracking this Medicare enrollment for revalidation, but has not published a due date.
Enrollment records
1
Earliest due date
Not assigned (TBD)
CMS data updated
2026-06-01
Revalidation progress
- Medicare enrolled
- On CMS revalidation list
- Due date assigned
- Revalidate in PECOS
CMS enrollment records
| Enrollment ID | Type | Specialty | State | Due date |
|---|---|---|---|---|
| I20031203000549 | I | Internal Medicine | CT | TBD |
What to do next
- No action required while the due date shows TBD.
- Check the CMS Revalidation Lookup Tool periodically — CMS updates the list about every 60 days.
- Do not submit a revalidation application in PECOS until CMS publishes a concrete due date.
Prepare CMS-855 application → · Look up this NPI in PECOS → · Verify on CMS PECOS
Medicare Utilization (FFS)
Source: CMS public data · Not endorsed by CMS · Beneficiary counts under 11 are suppressed in source data ·
Educational use only—not medical, billing, or legal advice.
Top Medicare procedures (2023) · refreshed 2026-05-27
| HCPCS | Description | Services | Beneficiaries | Medicare allowed |
|---|---|---|---|---|
| 99213 | Established patient office or other outpatient visit, 20-29 minutes | 178 | 75 | $0 |
| 36415 | Insertion of needle into vein for collection of blood sample | 136 | 98 | $0 |
| 81002 | Urinalysis, manual test | 99 | 88 | $0 |
| 93000 | Routine electrocardiogram (ecg) using at least 12 leads with interpretation and report | 81 | 76 | $0 |
| 94010 | Test to measure expiratory airflow and volume | 78 | 78 | $0 |
Insurance plans in this area (ZIP 06820)
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Provider's Procedures
| Specialty | Practice State | HCPCS Code | Description | Service Count | Beneficiary Count |
|---|---|---|---|---|---|
| INTERNAL MEDICINE | CT | 81002 | Urinalysis, manual test | 71 | 63 |
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