Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.
NPIDirectory

Theresa K Hayssen, MD

Individual provider Colon & Rectal Surgery Physician · NPI 1265412365

Theresa K Hayssen, MD practises General Surgery in Brookfield, Wisconsin. Graduated from Southern Illinois University School of Medicine in 1992, 34 years ago. Practices with Ascension Medical Group-Southeast Wisconsin Inc, a 555-clinician group and accepts Medicare assignment. Licensed in Wisconsin.

Years since qualifying
34
Trained at
Southern Illinois University School of Medicine
Licensed in
WI
In the registry since
2006
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

17000 W North Ave Ste 107W
Brookfield, WI 53005-4423 Not confirmed with CMS for 11 years — call before visiting
Phone: (262) 786-3722
Fax: (262) 786-0116
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Colon & Rectal Surgery Physician (primary) Taxonomy 208C00000X · Licence 39624 (WI)

Record details

NPI number1265412365
Entity typeIndividual (Type 1)
GenderFemale
Credentials MD
Sole proprietorNo
NPI enumeratedJanuary 17, 2006
Last updated in NPPESFebruary 10, 2015

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyGENERAL SURGERY
Medical schoolSOUTHERN ILLINOIS UNIVERSITY SCHOOL OF MEDICINE
Graduated 1992 (34 years in practice)
Group practice Ascension Medical Group-Southeast Wisconsin Inc — 555 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations9 on file with Medicare

Procedures

From CMS Care Compare, which counts the procedures a clinician billed to Original Medicare and Medicare Advantage over a recent 12-month period. CMS reports a fixed list of common procedures, so this is not everything the clinician does. Counts of 10 or fewer are given as a range, because CMS withholds small numbers.

Colonoscopy 19 times · 47th percentile
Removal or shaving of skin growth 1–10 times
Skin biopsy 1–10 times

The percentile compares how often this clinician performed the procedure with other clinicians who performed it, as CMS calculates it. It measures volume, not outcomes or skill.

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients98
Services billed 211 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Payments from drug and device companies, 2025

Drug and device makers are required by federal law (the Physician Payments Sunshine Act) to report what they pay or give to clinicians, and CMS publishes the reports as Open Payments. This is the 2025 program year. A report is a record of a payment, not an allegation of anything, and many are small items such as meals. Only general payments are listed here; research payments and ownership or investment interests are reported separately by CMS and are not shown.

Food and Beverage $436 3 payments · a meal or drink at a meeting or visit, not a fee
Travel and Lodging $156 3 payments · travel or lodging paid or reimbursed, such as to attend a conference

Each amount is the sum of what companies reported for that kind of payment in 2025, rounded to the dollar. Not all of it is income to the clinician: a meal is not a fee, a charitable contribution goes to a charity, and a royalty or an acquisition payment is not a salary.

Check a report, or dispute one, at the source in CMS’s own tool, Open Payments. Corrections go through CMS’s dispute process. This site removes a home address on request and asks for no proof, because that is privacy; it will not remove an accurate payment report on request, because that is a statutory public disclosure.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Ascension Medical Group-Southeast Wisconsin Inc

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 555 clinicians in the practice; 12 are shown here.

Other providers in Brookfield