Ambulatory Surgical Centers operate under a distinct Medicare reimbursement system (ASC Payment System) and require precise CPT coding for procedures and accurate ICD-10 diagnosis codes supporting medical necessity. This page reflects the FY2026 ICD-10-CM code set (effective October 1, 2025) and CPT 2026 procedure codes, and covers the top diagnosis codes and surgical procedure codes used in ASC settings across the United States.
FY 2027 ICD-10-CM (CMS, eff. 10/1/2026) · CPT 2026 (AMA) · All codes verified billable · Last verified: October 2026
Common CPT Codes for ASC Ambulatory Surgery Billing
CPT Code
Description
Medicare Rate*
Common Modifiers
27447
Total knee arthroplasty (facility fee only in ASC)
~N/A (facility only)
-LT, -RT, -50
43239
Esophagogastroduodenoscopy (EGD) with biopsy
~N/A (facility only)
-52, -53, -59
45378
Colonoscopy, flexible, diagnostic; with or without collection of specimen(s)
~N/A (facility only)
-52, -53, -33
29827
Arthroscopy, shoulder, surgical; with rotator cuff repair
~N/A (facility only)
-LT, -RT, -59
52000
Cystourethroscopy (separate procedure)
~N/A (facility only)
-52, -59, -51
66984
Extracapsular cataract removal with insertion of intraocular lens prosthesis
~N/A (facility only)
-LT, -RT, -50
45380
Colonoscopy, flexible; with biopsy, single or multiple
~N/A (facility only)
-52, -53, -33
45385
Colonoscopy, flexible; with removal of tumor(s), polyp(s) by snare technique
~N/A (facility only)
-52, -53, -33
29881
Arthroscopy, knee, surgical; with meniscectomy (medial or lateral)
~N/A (facility only)
-LT, -RT, -59
47562
Laparoscopic cholecystectomy
~N/A (facility only)
-22, -51
49650
Laparoscopic repair of initial inguinal hernia
~N/A (facility only)
-LT, -RT, -50
64483
Injection, anesthetic/steroid; lumbar or sacral, transforaminal epidural
~N/A (facility only)
-50, -LT, -RT, -59
27130
Total hip arthroplasty
~N/A (facility only)
-LT, -RT
43235
Esophagogastroduodenoscopy, flexible; diagnostic
~N/A (facility only)
-52, -53
26055
Tendon sheath incision (e.g., for trigger finger)
~~
-F1-F9, -59
20610
Arthrocentesis, aspiration and/or injection, major joint or bursa
~~
-LT, -RT, -59
99213
Office or other outpatient visit, established patient, low to moderate complexity
~~
-25, -95, -GT
36415
Collection of venous blood by venipuncture
~~
–
43889
Gastric restrictive procedure, transoral, endoscopic sleeve gastroplasty (ESG), including argon plasma coagulation, when performed (new CPT 2026 code)
~N/A (facility only)
-52, -53
66991
Extracapsular cataract removal with IOL insertion; with insertion of intraocular anterior segment aqueous drainage device (MIGS stent), without extraocular reservoir
~N/A (facility only)
-LT, -RT, -50
*Approximate 2026 CMS national non-facility rate. Rates vary by geography, setting, and payer contract. Refer to the CMS Physician Fee Schedule for official rates.
Top Denial Reasons for ASC Ambulatory Surgery Claims
⚠
Medical Necessity Not Documented
Payers deny claims when the diagnosis does not clearly support the procedure performed in the ASC setting. Ensure the operative report and pre-authorization documentation explicitly link the ICD-10 diagnosis code to the CPT procedure and include supporting clinical notes.
⚠
Missing or Incorrect Modifier
Bilateral procedures, laterality, or distinct procedural services without the appropriate modifier (-LT, -RT, -50, -59) are a leading cause of ASC claim rejections. Review modifier requirements per payer policy for every multi-procedure or bilateral claim before submission.
⚠
Prior Authorization Not Obtained
Many commercial and Medicare Advantage plans require pre-authorization for ASC procedures such as total joint replacement or complex GI endoscopy. Verify authorization requirements before scheduling and retain the authorization number on file for claims submission.
⚠
Duplicate Claim or Unbundling Error
Submitting both a component code and a comprehensive code for the same encounter triggers automatic denials under CCI edits. Audit your charge capture against CMS NCCI bundling edits before submission and use modifier -59 only when a distinct service is clearly documented.
ASC (Ambulatory Surgery) Billing & Coding Tips
The ASC Medicare Covered Procedures List (CPL) changes annually — verify that each procedure is on the CPL before scheduling, as non-covered procedures cannot be billed to Medicare as ASC services.
Medical necessity diagnoses must directly support the procedure — a cataract surgery CPT without a documented visual impairment ICD-10 will be denied on pre-payment review.
ASCs bill the facility fee only (place of service 24); the surgeon bills separately. Do not include the surgeon’s professional fee in the ASC claim.
Modifier -74 (discontinued outpatient procedure after anesthesia) and -73 (discontinued prior to anesthesia) are ASC-specific — use them when procedures are cancelled after the patient has been prepped.
The ASC Covered Procedures List (CPL) is the annual list of procedures CMS approves for payment under the ASC Payment System. Procedures not on the list cannot be billed to Medicare as ASC services — they must be performed in a hospital outpatient department or office setting. The CPL is updated each January in the OPPS/ASC final rule.
What is place of service code for an ASC claim?
Use POS 24 (Ambulatory Surgical Center) on professional claims when a procedure is performed in an ASC. The ASC itself bills the facility fee on an institutional claim (UB-04) using POS 24 and type of bill 083x. The surgeon’s professional fee uses POS 24 on the CMS-1500.
What modifier is used for a cancelled ASC procedure?
Modifier -73 is used when a procedure is discontinued prior to administration of anesthesia (50% of the ASC payment rate is paid). Modifier -74 is used when discontinued after anesthesia has been induced (full payment). Both require documentation of the reason for cancellation.
How is colonoscopy screening vs. diagnostic coded?
Z12.11 is used for a screening colonoscopy (no symptoms, no prior history). If the colonoscopy begins as a screening but polyps are found and removed, the procedure code changes to the therapeutic colonoscopy CPT (45385), but Z12.11 remains the primary diagnosis under current CMS guidance.
How does OmniMD support ASC operations?
OmniMD’s ASC EHR includes surgical scheduling with pre-authorization tracking, anesthesia documentation, procedure CPT linking to ICD-10 diagnosis codes, and ASC-specific billing workflows with modifier management and covered procedure list verification.
Streamline Your ASC (Ambulatory Surgery) Practice with OmniMD
Purpose-built EHR, billing, and practice management for ASC (Ambulatory Surgery) practices.
