Dennis G. Oneill, MD

Medicare activity in 2024

Official CMS public-use data for Dennis G. Oneill, 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. Pathology examination of tissue using a microscope, intermediate complexity (88305)969 services
2. Special stained specimen slides to examine tissue including interpretation and report (88313)374 services
3. Special stained specimen slides to examine tissue, initial procedure (88342)141 services
4. Special stained specimen slides to identify organisms including interpretation and report (88312)91 services
5. Cell examination of specimen, selective cellular enhancement technique (88112)34 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 cholesterol75%
• High blood pressure73%
• Arthritis43%
• Diabetes27%
• Ischemic heart disease25%
• Anxiety22%

Hospitals where Dennis G. Oneill works

Medicare's Facility Affiliation Data lists Dennis G. Oneill 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.

• Manchester Memorial HospitalManchester, CT · Acute Care Hospital · Medicare rating: 4 of 5 stars · Emergency services: listed by Medicare · CCN 070027

Practice locations

Addresses where Dennis G. Oneill is enrolled with Medicare (CMS data updated October 2, 2026).

• 1290 Silas Deane HwyWethersfield, CT 06109 (860) 859‑9061
• 71 Haynes StManchester, CT 06040 (860) 647‑6487
• 85 Seymour St, Suite 1000Hartford, CT 06106 (860) 246‑2571
• 90 Morgan St, Suite 301Stamford, CT 06905 (203) 998‑7400

Group practices

Medicare enrollment lists Dennis G. Oneill as a member of these groups (CMS data updated October 2, 2026).

• Connecticut Gi PLLC248 clinicians in the group
• Eastern Connecticut Pathology Consultants, PC20 clinicians in the group
• Stamford Gastroenterology Inc4 clinicians in the group

Specialties

• Pathologyprimary

Find other Pathology doctors in Connecticut →

Other pathologists in Wethersfield

Clinicians with the same Medicare primary specialty in Wethersfield, CT — not a recommendation.

• Angela C. Fields, MD
• Samuel Ballentine, MD
• Ayesha S. Siddique, MD
• Susan M. Gobel, MD
• Anshu Trivedi, MD
• Gerald Bailey, MD
• Bela A. Horvath, MD

All pathologists in Wethersfield →

Other clinicians in Connecticut Gi PLLC

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

• Kevin T. Pelland Jr., MD
• Sarah M. Canavan, MD
• Chelsea Veranis
• Michelle C. Tong, MD
• Tasha M. Ramos
• Mari P. Looney

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