ASC (Ambulatory Surgery) ICD-10 Codes & CPT Codes

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 covers the top diagnosis codes and surgical procedure codes used in ASC settings across the United States.

FY 2026 ICD-10-CM (CMS) · CPT codes updated annually · All codes verified billable · Last verified: June 2026

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Top ICD-10 Codes for ASC (Ambulatory Surgery)

ICD-10 Code Description Billable
M17.11 Primary osteoarthritis, right knee ✓
M16.11 Primary osteoarthritis, right hip ✓
M75.100 Unspecified rotator cuff tear or rupture of right shoulder ✓
K57.30 Diverticulosis of large intestine without perforation or abscess without bleeding ✓
Z12.11 Encounter for screening for malignant neoplasm of colon ✓
M51.16 Intervertebral disc degeneration, lumbar region ✓
S83.006A Unspecified tear of unspecified meniscus, current injury, initial encounter ✓
N20.0 Calculus of kidney ✓
G89.29 Other chronic pain ✓
Z47.89 Encounter for other specified orthopedic aftercare ✓
K35.80 Other and unspecified acute appendicitis without abscess ✓
H26.9 Unspecified cataract ✓
N40.1 Benign prostatic hyperplasia with lower urinary tract symptoms ✓
Z48.812 Encounter for surgical aftercare following surgery on respiratory system ✓
Z09 Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm ✓
K40.90 Unilateral inguinal hernia, without obstruction or gangrene, not specified as recurrent ✓
M23.201 Derangement of unspecified lateral meniscus due to old tear or injury, right knee ✓
H04.123 Dry eye syndrome of bilateral lacrimal glands ✓
K80.20 Calculus of gallbladder without cholecystitis, without obstruction ✓
M54.50 Low back pain, unspecified ✓
N13.30 Unspecified hydronephrosis ✓
K92.1 Melena ✓
M25.511 Pain in right shoulder ✓
Z23 Encounter for immunization ✓
H35.30 Unspecified macular degeneration ✓
M79.3 Panniculitis, unspecified ✓
K56.600 Unspecified intestinal obstruction, unspecified as to partial versus complete obstruction ✓
N18.3 Chronic kidney disease, stage 3 (moderate) ✓
G54.2 Cervical root disorders, not elsewhere classified ✓
M65.311 Trigger finger, right index finger ✓
K21.0 Gastro-esophageal reflux disease with esophagitis ✓
H25.11 Age-related nuclear cataract, right eye ✓
M47.816 Spondylosis without myelopathy or radiculopathy, lumbar region ✓
N32.81 Overactive bladder ✓
K57.20 Diverticulitis of large intestine with perforation and abscess without bleeding ✓
M16.10 Unilateral primary osteoarthritis, unspecified hip ✓
S62.001A Fracture of unspecified carpal bone, right wrist, initial encounter for closed fracture ✓
H40.1110 Primary open-angle glaucoma, right eye, stage unspecified ✓
K43.9 Ventral hernia without obstruction or gangrene ✓
M75.30 Calcific tendinitis of unspecified shoulder ✓

Source: CMS ICD-10-CM Official Code Set FY 2026

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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 ~~ –

*Approximate 2025 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

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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.

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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.

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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.

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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.

Frequently Asked Questions

What is the ASC Medicare Covered Procedures List?

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.

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