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    v1.0.30
    OpenPayerBilling CodesOther Procedures on the Colon and RectumCPT cpt-45399-unlisted-procedure-on-colon
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    CPT 45399: Unlisted Procedure on Colon

    CPT code 45399 is an unlisted procedure code for operations on the colon and is used when a specific CPT code does not describe the performed colon procedure; the service type is a surgical procedure on the colon and the typical site of service is an operating room or procedural/surgical suite for colon surgery.

    For related coverage guidance, see recent payer policy updates: Percutaneous Electrical Nerve Field Stimulation for Functional Abdominal Pain Disorders, Esophagogastroduodenoscopy (EGD) Coverage Policy, Radiofrequency Therapy for Fecal Incontinence.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is a 58-year-old male presenting with persistent abdominal pain, altered bowel habits, and unexplained rectal bleeding. After colonoscopy and standard endoscopic interventions, the endoscopist encounters an unusual or complex colon procedure not described by an existing CPT code—for example, an extensive endoscopic submucosal dissection of a large nonpolypoid lesion, a novel endoscopic full-thickness resection technique, or an unlisted combined open and endoscopic procedure on the colon. The clinical workflow begins with pre-procedure evaluation (history, medication reconciliation, informed consent), diagnostic colonoscopy with localization and documentation of the lesion, performance of the atypical therapeutic procedure, intra-procedural anesthesia management, specimen handling for pathology, and immediate post-procedure recovery and discharge instructions. Documentation must detail the indication, findings, step-by-step technique, duration, personnel, complexity, complications (if any), and rationale for using an unlisted code 45399 because no specific CPT code describes the service performed.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    45380Colonoscopy with removal of tumor(s), polyp(s), or other lesion by snare techniqueCommonly performed when polypectomy is feasible; may be performed before or instead of an unlisted colon procedure if lesion is amenable to snare resection.
    45385Colonoscopy with endoscopic mucosal resection (EMR)Used for piecemeal or en bloc EMR of sessile lesions; a complex lesion requiring a novel technique may be reported as 45399 instead of this code when not fitting EMR descriptors.
    45390Colonoscopy with submucosal injection for lesion removalPerformed as an adjunct to mucosal resection; may precede an unlisted advanced resection.
    44140Colectomy, partial; with anastomosisAn open surgical resection option that may be performed instead of or in combination with advanced endoscopic techniques documented under 45399.
    43258Upper GI endoscopic procedure with endoscopic submucosal dissection (ESD)Represents advanced endoscopic dissection technique conceptually similar to full-thickness or advanced submucosal colon work reported with 45399 when no colon-specific ESD code exists.

    Related Modifiers

    9 rows

    ModifierDescriptionWhen to Use
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…
    66Modifier 66 (Surgical Team) is used when three or more surgeons act as primary surgeons on a single, highly complex procedure. The AMA defines it for use when a surgical team — often composed of…- Use modifier 66 when three or more surgeons act as primary surgeons working collaboratively as a surgical team on a single, highly complex or difficult procedure (for example organ…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    78CPT modifier -78 indicates an unplanned, related return to the operating or procedure room by the same provider during the global postoperative period. It is appended when treatment for a…- Use modifier -78 when an unplanned, related complication during the original procedure’s global postoperative period requires the patient to return to a formal operating or procedure room and the…
    74Modifier ‑74 indicates an outpatient hospital or ASC procedure that was discontinued after anesthesia was administered and after the procedure had begun. Use this modifier when anesthesia (local,…- Use modifier -74 when a procedure in an outpatient hospital or ASC setting is terminated after anesthesia has been administered and after the procedure has commenced (for example, after incision,…
    73Modifier 73 indicates a facility-level outpatient hospital or ASC procedure that was discontinued after the patient was prepared and taken to the procedure/operating room but before any anesthesia…- When to use: Apply CPT modifier 73 on the FACILITY (outpatient hospital or ASC) claim when the patient has been fully prepared and physically taken into the procedure/operating room but the…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    207RC0000X
    208D00000X
    207L00000X
    208100000X
    3336C0003X
    1835P2201X
    106E00000X
    152WX0102X

    Related ICD-10-CM Codes

    30 rows

    ICD-10-CM CodeDescription
    C18.9Malignant neoplasm of colon, unspecified
    C19Malignant neoplasm of rectosigmoid junction
    C20Malignant neoplasm of rectum
    D12.6Benign neoplasm of colon, unspecified
    K50.90Crohn's disease, unspecified, without complications
    K51.90Ulcerative colitis, unspecified, without complications
    K52.9Noninfective gastroenteritis and colitis, unspecified
    K55.9Vascular disorder of intestine, unspecified
    K57.00Diverticulitis of small intestine with perforation and abscess without bleeding
    K57.10Diverticulosis of small intestine without perforation or abscess without bleeding

    Showing 1–10 of 30

    Related Payer Policy Updates

    Specialty: Gastroenterology1 / 3

    10 rows

    PolicyPayerEffective Date
    Percutaneous Electrical Nerve Field Stimulation for Functional Abdominal Pain Disordersbcbsvermont2026-12-01
    Esophagogastroduodenoscopy (EGD) Coverage Policyevicore2026-11-05
    Radiofrequency Therapy for Fecal IncontinenceCigna2026-10-15
    Magnetic Sphincter Augmentation for the Treatment of Gastroesophageal Reflux Disease (GERD)univerahealthcare2026-10-15
    High-Resolution Anoscopy (HRA)Premera Bluecross2026-10-01
    Gastroesophageal and Gastrointestinal (GI) Services and ProceduresColorado Rocky Mountain Health Plans2026-10-01
    Fecal Analysis in the Diagnosis of Intestinal Dysbiosis and Fecal Microbiota Transplant TestingOscar Health2026-10-01
    Serum Testing for Hepatic Fibrosis in the Evaluation and Monitoring of Chronic Liver DiseaseOscar Health2026-10-01
    Pancreatic Enzyme Testing for Acute PancreatitisOscar Health2026-10-01
    Helicobacter pylori TestingOscar Health2026-10-01

    Related Codes

    CPT-45990-DIAGNOSTIC-ANORECTAL-EXAMINATION-UNDER-ANESTHESIA

    CPT 45990: Diagnostic Anorectal Examination Under Anesthesia

    CPT-45999-UNLISTED-RECTAL-PROCEDURE

    CPT 45999: Unlisted Procedure on Rectum

    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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