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DR. SARA JEAN SLEZAK D.O.
NPI 1285128926
Obstetrics & Gynecology in Chicago, IL

Active since June 17, 2018PECOS EnrolledAccepts Medicare Assignment
2001 S CALIFORNIA AVE STE 100, CHICAGO, IL 60608(773) 584-6200 Get Directions Write a Review

NPPES record last updated: January 22, 2026. Verified against the NPPES registry weekly; last sync: August 02, 2026.

Record update history: Jan 22, 2026, Sep 27, 2022, Jun 25, 2018 and 1 more (4 updates tracked since 2018).

About Dr. Sara Jean Slezak D.o. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. SARA JEAN SLEZAK D.O. (NPI 1285128926) is an individual obstetrics & gynecology provider in Chicago, Illinois, licensed in Illinois (036.161001) and active in the NPI registry since June 2018. She is enrolled in Medicare PECOS, maintains a secondary practice location in Chicago, and is a graduate of Midwestern University, Chicago College Of Osteopathic Med (2018).

NPPES Registry Identity

NPI1285128926
Entity TypeIndividualFemale
Primary Taxonomy207V00000X
Provider Legal NameDR. SARA JEAN SLEZAKCredential: D.O.
Location Address2001 S CALIFORNIA AVE STE 100Chicago, IL 60608-2486
Mailing Address2650 Ridge Ave Ste 1223Evanston, IL 60201-1700 · (847) 570-2040 · Fax (847) 570-5315
Phone(773) 584-6200
Sole ProprietorNo
Medical School CMSMidwestern University, Chicago College Of Osteopathic MedGraduated 2018
Enumeration DateJune 17, 2018
Last NPPES UpdateJanuary 22, 20264 updates tracked since enumeration
NPPES CertifiedJanuary 22, 2026
✔ NPI 1285128926 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyObstetrics & GynecologyAllopathic & Osteopathic Physicians
Taxonomy Code207V00000X
License✔ Licensed in IL · 036.161001
Definition
An obstetrician/gynecologist possesses special knowledge, skills and professional capability in the medical and surgical care of the female reproductive system and associated disorders. This physician serves as a consultant to other physicians and as a primary physician for women.
2001 S CALIFORNIA AVE STE 100, Chicago, IL 60608
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Other Names 1

Former Name (1)Sara Jean Twiehaus Do

Secondary Practice Location 1

Location 15140 N California Ave Ste 605Chicago, IL 60625-3645 · Phone (773) 878-7787 · Fax (773) 878-0788

Accepted Insurance

The full list of accepted plans is on the Insurance tab. Issuers include Ambetter from Home State Health, Ambetter Health, Ambetter Health of Delaware.Insurance ›

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Dr. Sara Jean Slezak D.o. 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.

PECOS PAC ID8426307612
PECOS Enrollment IDI20220825001474
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency✔ Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 60608 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$138.86 typical visit price
range $60.08 – $183.39
Typical copayment $34.71 (range $15.02 – $45.84)
Most-billed visit code 99204
Established Patient
$74.80 typical visit price
range $18.97 – $148.12
Typical copayment $18.70 (range $4.74 – $37.03)
Most-billed visit code 99213
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Other Providers at the Same Location NPPES 13

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

PAOLA SEGUIL M.S., R.D., L.D.N.
Dietitian, Registered
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 640-5784
MS. JESSICA LINDSAY BOLAND LCSW
Social Worker (Clinical)
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 916-4437
GEORGINA HARO LCSW
Counselor (Mental Health)
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 584-6200
LABORATORY CORPORATION OF AMERICA
Clinical Medical Laboratory
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 523-2549
MARIA LAURA CASALEGNO MD
Internal Medicine
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 584-6200
MARK D MINIER MD
Pediatrics
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 584-6200
DR. HANNAH L HARP MD
Pediatrics
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 584-6200
BECKY DENISE SERNA MSN, APRN, FNP-C
Nurse Practitioner (Family)
2001 S CALIFORNIA AVE STE 100
CHICAGO, IL 60608
Cook County (773) 584-6200

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 Sara Slezak's NPI number?

The NPI number for Sara Slezak is 1285128926. It was assigned to this individual provider in the NPPES registry on June 17, 2018. The provider is also known as Sara Jean Twiehaus Do.

Where is Sara Slezak located?

Sara Slezak practices at 2001 S California Ave Ste 100, Chicago, IL 60608. The listed phone number is (773) 584-6200.

What is Sara Slezak's specialty?

The primary specialty registered for this NPI is Obstetrics & Gynecology with taxonomy code 207V00000X.

Is Sara Slezak enrolled in Medicare?

Yes. Sara Slezak 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.

What insurance does Sara Slezak accept?

Health plans from Ambetter Health, Ambetter Health of Delaware and Ambetter from Home State Health list Sara Slezak as in-network in at least one marketplace plan. Coverage varies by plan and year; verify with the insurer or the provider before a visit.

When was this NPI record last updated?

The NPPES record for Sara Slezak was last updated on January 22, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 months 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.