The continual shift from inpatient to outpatient procedures is one of the most common ways hospitals and care facilities reduce healthcare spending. This is especially cost-effective when patients seek outpatient care at a clinic or ambulatory surgery center (ASC) rather than a traditional hospital. Because services are often limited at ASCs and outpatient clinics, these facilities are able to charge less than hospitals, whose charges must cover operating costs of a wide breadth of services and staff.
Major influencing factors in the shift to outpatient facilities and services include advances in surgical technology, improved outcomes via regulatory changes, edits to the Centers for Medicare and Medicaid Services (CMS) outpatient-only procedure list, and others.
Below, we've compiled list of the top 10 outpatient medical procedures at U.S. hospitals and ASCs for comparison.
Top 10 Hospital Outpatient Procedures by Volume
Number of Procedures
Complete blood count w/ differential white blood cell count
Comprehensive metabolic panel
Injection of propofol, 10 mg
Metabolic panel total ca
Urinalysis auto w/scope
Assay thyroid stimulating hormone
Fig 1Data from Definitive Healthcare based on 2018 Medicare and all-payor procedure estimates. YTD Medicare data is from the 2018 Medicare Quarterly SAF. Does not include visits to emergency departments or clinics.
Of the top 10 outpatient medical procedures at hospitals, seven are diagnostic tests and one is a precursor to anesthesia. The only two treatments present are "therapeutic exercises" and "assay thyroid stimulating hormone." Unlike at ASCs, patients often visit primary care physicians or urgent care clinics at hospitals for diagnoses rather than procedures and treatments. Patients are tested and receive diagnoses at hospitals before selecting where to undergo a procedure or other treatment.
Epidural steroid injection in lumbar spine w/ imaging guidance
After cataract laser surgery
Injection into lumbar/sacral spine w/ image guidance
Lumbar interlaminar epidural steroid injection
Colorectal screening; high risk individual
Fig 2 Data from Definitive Healthcare based on 2017 Medicare procedure estimates. Does not include visits to emergency departments or clinics.
Cataract surgeries are by far the most common ASC procedure with over 1.2 million claims in 2017, with botox injections taking the next highest slot. There are no reports of "routine venipunctures" or other diagnostic panels at ASCs, which notably make up the majority of hospital outpatient procedures. The ability of ASCs to focus solely on treatments rather than diagnostics means these facilities are likely able to charge patients less than hospitals for the same procedures, as ASCs have fewer lab fees or other related costs to cover.