Mary Ahn, MD

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.

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.

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.

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. Those with a page here are linked.

• Northwestern Medicine Delnor Community Hospital Hospital · Geneva, IL · listed as Delnor Community Hospital
• Northwestern Memorial Hospital Hospital · Chicago, IL
• Northwestern Medicine Central Dupage Hospital Hospital · Winfield, IL
• Northwestern Medicine McHenry Hospital · McHenry, IL

Colleagues at Northwestern Medical Faculty Foundation

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 4394 clinicians in the practice; 12 are shown here.

• Fiaz Ahmed, MD Anesthesiology Physician · Arlington Heights, IL
• Ali A Baaj, MD Neurological Surgery Physician · New York, NY
• Dr. Gonzalo Castillo, MD Anesthesiology Physician · Winfield, IL
• Dr. Charley Ding, MD Anesthesiology Physician · Elgin, IL
• Dr. Dina Michael Elaraj, MD Surgery Physician · Chicago, IL
• Daniel R Ganger, MD Hepatology Physician · Chicago, IL
• Dr. Jason Hyunsuk Ko, MD Plastic Surgery Physician · Chicago, IL
• Dr. Dean T Monma, MD Specialist · Winfield, IL
• Saad Muhammad, MD Hospitalist Physician · Urbana, IL
• William B Seiden, MD Internal Medicine Physician · Lake Forest, IL
• Robin Lynn Solini, PA Physician Assistant · Chicago, IL
• Anuja Thakkar Walsh, DO Anesthesiology Physician · Lake Forest, IL

Other providers in Winfield

• Associated General Surgeons, SC

  Organization Surgery Physician · NPI 1174501266

  25 N Winfield Rd Ste 410, Winfield, IL 60190-1237 · (630) 665-2101

• Benjamin Chaney

  Individual Surgery Physician · NPI 1871019182

  25 N Winfield Rd, Winfield, IL 60190-1379 · (630) 933-6675

• Dr. David Owen Woodard, MD

  Individual Surgery Physician · NPI 1447231782

  25 N Winfield Rd Ste 410, Winfield, IL 60190 · (630) 665-2101