What CMS Actually Tells You About Surgery Center Safety
Most surgery in America no longer happens in a hospital. It happens in one of the 5,611 ambulatory surgery centers CMS tracks — and if you try to find out whether the one near you is any good, this is what you get: across CMS's four risk-adjusted outcome measures, exactly 7 facilities in the entire country are identified as better or worse than expected. 3 of those four measures categorize nobody at all.
We went looking for the worst surgery centers in America. We came back with a story about the measuring instrument instead.
Download the full dataset (CSV)Free, CC0. Every figure on this page, by measure and state.
Four risk-adjusted measures. 7 facilities distinguished.
These are the measures designed for comparison: CMS adjusts for how sick each facility's patients are, then sorts every center into a performance category. In principle this is exactly what a patient wants. In practice, here is the entire national result.
| Measure | Better | Worse | No different | Too few cases | Not reported |
|---|---|---|---|---|---|
| Hospital visits after outpatient colonoscopyASC-12CATEGORIZES NOBODY | 0 | 0 | 0 | 161 | 3,494 |
| Hospital visits after orthopedic proceduresASC-17CATEGORIZES NOBODY | 0 | 0 | 0 | 1,152 | 2,618 |
| Hospital visits after urology proceduresASC-18CATEGORIZES NOBODY | 0 | 0 | 0 | 489 | 4,547 |
| Hospital visits after general surgeryASC-19 | 4 | 3 | 1,406 | 2,116 | 2,082 |
Who reports what — and how often the answer is zero
The other CMS measures are plain rates. Two things limit them: many facilities publish nothing, and among those that do, most report exactly 0.000. Some of those zeros are real — burns and wrong-site surgery genuinely are rare events. But a measure where nearly every reporting facility returns the same number cannot separate a good center from a bad one.
| Measure | Facilities reporting | % of all centers | Reporting exactly 0.000 | Zeros as % of reporters |
|---|---|---|---|---|
| All-cause hospital transfer or admissionASC-4 | 3,971 | 71% | 706 | 18% |
| Patient fallASC-2 | 3,395 | 61% | 1,752 | 52% |
| Wrong site, side, patient, procedure or implantASC-3 | 2,998 | 53% | 2,571 | 86% |
| Patient burnASC-1 | 2,899 | 52% | 2,687 | 93% |
| Normothermia outcomeASC-13 | 2,193 | 39% | 0 | 0% |
| Endoscopy — appropriate follow-up intervalASC-9 | 1,739 | 31% | 0 | 0% |
| Unplanned anterior vitrectomyASC-14 | 1,621 | 29% | 270 | 17% |
| Cataracts — improvement in visual functionASC-11 | 120 | 2% | 0 | 0% |
States whose surgery centers publish the least — bottom 12
Average share of the 8 CMS safety measures that a state's surgery centers actually report. This ranks transparency, not safety — the whole point of this study is that the data does not support a safety ranking.
Surgery center reporting completeness, state by state
Ranked most complete first. States with fewer than 10 surgery centers are excluded. Again: this measures how much a state's facilities disclose, not how safe they are.
| # | State | Reporting completeness | Avg measures reported | Surgery centers |
|---|---|---|---|---|
| 1 | Alabama | 60.7% | 4.9 / 8 | 49 |
| 2 | Minnesota | 58.1% | 4.7 / 8 | 86 |
| 3 | Montana | 57.4% | 4.6 / 8 | 22 |
| 4 | Iowa | 57.3% | 4.6 / 8 | 29 |
| 5 | North Dakota | 55.7% | 4.5 / 8 | 11 |
| 6 | Wyoming | 55.6% | 4.5 / 8 | 20 |
| 7 | Alaska | 55.0% | 4.4 / 8 | 15 |
| 8 | Connecticut | 53.8% | 4.3 / 8 | 52 |
| 9 | Delaware | 52.8% | 4.2 / 8 | 22 |
| 10 | Nebraska | 50.5% | 4.0 / 8 | 47 |
| 11 | Kentucky | 49.6% | 4.0 / 8 | 34 |
| 12 | Michigan | 49.6% | 4.0 / 8 | 115 |
| 13 | Maine | 49.1% | 3.9 / 8 | 14 |
| 14 | Illinois | 48.6% | 3.9 / 8 | 129 |
| 15 | Oregon | 48.2% | 3.9 / 8 | 88 |
| 16 | North Carolina | 48.0% | 3.8 / 8 | 134 |
| 17 | Utah | 47.2% | 3.8 / 8 | 49 |
| 18 | Massachusetts | 47.0% | 3.8 / 8 | 55 |
| 19 | Kansas | 46.8% | 3.7 / 8 | 67 |
| 20 | New Hampshire | 46.8% | 3.7 / 8 | 27 |
| 21 | Wisconsin | 46.4% | 3.7 / 8 | 80 |
| 22 | Oklahoma | 46.4% | 3.7 / 8 | 38 |
| 23 | Indiana | 46.3% | 3.7 / 8 | 140 |
| 24 | Tennessee | 46.0% | 3.7 / 8 | 137 |
| 25 | Virginia | 45.8% | 3.7 / 8 | 68 |
| 26 | South Carolina | 45.2% | 3.6 / 8 | 75 |
| 27 | Colorado | 45.0% | 3.6 / 8 | 125 |
| 28 | New Mexico | 44.7% | 3.6 / 8 | 19 |
| 29 | Texas | 44.7% | 3.6 / 8 | 424 |
| 30 | Arizona | 44.4% | 3.5 / 8 | 204 |
| 31 | Mississippi | 44.3% | 3.5 / 8 | 68 |
| 32 | Florida | 43.8% | 3.5 / 8 | 478 |
| 33 | Ohio | 42.7% | 3.4 / 8 | 187 |
| 34 | Louisiana | 42.2% | 3.4 / 8 | 86 |
| 35 | Missouri | 42.0% | 3.4 / 8 | 102 |
| 36 | Pennsylvania | 41.7% | 3.3 / 8 | 233 |
| 37 | New York | 38.5% | 3.1 / 8 | 167 |
| 38 | Arkansas | 38.4% | 3.1 / 8 | 68 |
| 39 | Washington | 37.4% | 3.0 / 8 | 163 |
| 40 | Idaho | 36.7% | 2.9 / 8 | 49 |
| 41 | California | 36.7% | 2.9 / 8 | 645 |
| 42 | Nevada | 36.2% | 2.9 / 8 | 68 |
| 43 | New Jersey | 35.7% | 2.9 / 8 | 217 |
| 44 | Rhode Island | 35.0% | 2.8 / 8 | 15 |
| 45 | Hawaii | 33.9% | 2.7 / 8 | 21 |
| 46 | Georgia | 33.1% | 2.7 / 8 | 341 |
| 47 | Maryland | 31.6% | 2.5 / 8 | 284 |
| 48 | South Dakota | 30.4% | 2.4 / 8 | 14 |
| 49 | Puerto Rico | 13.3% | 1.1 / 8 | 15 |
Methodology
Figures come from the CMS Ambulatory Surgical Center Quality Measures facility file, covering 5,611 centers. We read every safety measure CMS publishes and counted three things per measure: how many facilities report a usable value, how many of those report exactly 0.000, and how many report nothing. For the four risk-standardized measures we counted CMS's own performance categories directly. CMS writes missing values as either "N/A" or "Not Available" depending on the measure; both are treated as not reported.
We set out to rank surgery centers by safety and concluded that we should not. The risk-standardized rates are shrunk so heavily toward the national mean that CMS itself places almost every facility in the same bucket, and three of the four measures place no facility in any bucket at all. Ordering states or facilities by those rates would produce a ranking that looks authoritative and carries no information. The state table here ranks disclosure, and is labelled as such.
None of this means surgery centers are unsafe. It means the public data cannot tell you either way — which matters, because the procedures that moved out of hospitals and into these facilities went with them into a much dimmer reporting regime. Hospitals, by comparison, report readmissions in a form that does separate them: see hospital readmission rates by state.
Cite or embed this study
This research is free to reference. Journalists and researchers are welcome to cite the figures with a link back to CareLens.
CareLens. (2026). What CMS Actually Tells You About Surgery Center Safety. Retrieved from https://carelens.io/surgery-center-safety
<a href="https://carelens.io/surgery-center-safety" style="display:inline-block;border-left:4px solid #84cc16;padding:10px 14px;font:14px/1.4 system-ui,sans-serif;color:#0f172a;text-decoration:none;background:#f8fafc;border-radius:4px;max-width:520px"><strong>Across 5,611 US surgery centers, CMS identifies just 7 as better or worse than expected</strong><br>Source: CareLens — What CMS Actually Tells You About Surgery Center Safety (2026)</a>
Source: CareLens — What CMS Actually Tells You About Surgery Center Safety (2026)