The outpatient surgery center gold rush

The number of procedures taking place in outpatient surgery centers — where people go under the knife and return home the same day — is expected to rise from 23 million in 2018 to 27 million in 2021, according to estimates from consulting firm Bain & Co.

Why it matters: Surgeries in freestanding centers cost less than those that happen in hospital outpatient departments, which is why many insurers and policymakers are pushing for this shift.

The big picture: But that doesn't mean it's an unprofitable niche. Surgery centers would generate $43 billion worth of procedures if those estimates hold up.

Between the lines: Medicare has made it clear it will pay for more surgeries, especially orthopedic procedures like joint replacements, outside of the hospital. Industry giants have been placing their bets on these facilities for years.

• Health insurers: UnitedHealth Group bought Surgical Care Affiliates for $2.3 billion in 2017.
• Hospitals: Tenet Healthcare and HCA Healthcare each own more than 120 surgery centers, and many not-for-profit hospitals own stakes in their local surgery centers.
• Private equity firms: Bain Capital, the PE arm that was spun out of Bain & Co., owns two-thirds of Surgery Partners, a surgery center chain that's on pace to collect $1.7 billion of revenue this year.

Go deeper: Health care sees dollar signs in surgery centers