Outpatient surgery under Medicare: ambulatory surgical centers vs hospitals

How Medicare pays for outpatient surgery at hospital outpatient departments and ambulatory surgical centers, why costs differ, and what to ask before surgery.

Many procedures, from colonoscopies to joint replacements, happen without an overnight stay. Medicare pays for them under Part B.

Where you have surgery matters

Ambulatory surgical centers often have lower Medicare-approved amounts than hospital outpatient departments, so your 20% is smaller.

Questions to ask

1. Is this inpatient or outpatient?
2. Is the facility an ambulatory surgical center or a hospital department?
3. Do all providers, including anesthesia, accept Medicare assignment?
4. Will I receive an Advance Beneficiary Notice? See the ABN.

Screening colonoscopy

A screening colonoscopy is free, but if a polyp is removed, coinsurance may apply. That cost-sharing has been phasing down and reaches $0 in 2030.

Coverage gaps

Part B's 20% has no cap in Original Medicare; see Part B costs and consider whether a Medigap plan fits.

Questions people ask

Is outpatient surgery Part A or Part B?

Part B.

Are surgical centers cheaper?

Often, with lower approved amounts.

Is screening colonoscopy free?

Yes, though polyp removal may add coinsurance.

Does Part B have an out-of-pocket cap?

No, in Original Medicare.

Independent educational site. Not affiliated with or endorsed by the U.S. government, the federal Medicare program, or any insurance company. Figures are 2026 amounts published by CMS unless noted; check Medicare.gov for your situation.