Tenet's United Surgical Partners International and Optum's SCA Health are the two largest ASC chains by number of centers.
Here are the top five, based on the most recent information available:
1. USPI (Dallas): 520+
2. SCA Health (Deerfield, Ill.): 320+
3. AmSurg (Nashville, Tenn.): 250+
4. HCA Healthcare (Nashville): 150+
5. Surgery Partners (Brentwood, Tenn.): 165 surgical facilities