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    v1.0.30
    OpenPayerBilling CodesSurgical Procedures on the Omental FlapCPT cpt-49999-peritoneum-omental-unlisted-procedure
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    CPT 49999: Peritoneum and Omentum Procedure, Unlisted

    CPT code 49999 is an unlisted procedure code used to report surgical procedures on the peritoneum and omentum in the abdomen when no specific CPT code exists for the performed service; the service type is abdominal surgery and the typical site of service is an operating room or facility-based surgical setting where intra-abdominal procedures are performed.

    For related coverage guidance, see recent payer policy updates: Surgical Procedures, Outpatient Surgical Procedures - Site of Service, Site of Service Ambulatory Service Center (ASC) Select — Surgical or Diagnostic Procedures in Adults.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult undergoing abdominal exploration for suspected peritoneal or omental pathology not covered by a specific CPT code. Example scenario: a 62-year-old patient with a history of colorectal cancer presents with increasing abdominal pain and ascites. Imaging suggests omental carcinomatosis with suspicious nodules on the peritoneal surfaces. The surgeon performs an open or laparoscopic exploratory procedure targeting the peritoneum and omentum to obtain diagnostic biopsies, perform omental resection of tumor deposits, and evaluate for peritoneal spread. The procedural workflow includes anesthesia evaluation, intraoperative inspection of the peritoneal cavity, targeted biopsies or partial omentectomy, hemostasis, specimen labeling and submission to pathology, and postoperative monitoring in the post-anesthesia care unit. Use of 49999 is appropriate when the specific peritoneal or omental procedure performed cannot be accurately reported with an existing CPT code, such as an unusual or combined peritoneal debulking maneuver that lacks a defined code. Documentation should describe surgical findings, the exact operative steps, extent of resection, estimated blood loss, specimens submitted, and any concurrent procedures and modifiers applied.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    49083Laparoscopy, surgical, exploratory, with biopsy(s) (single or multiple)Commonly performed prior to or instead of an unlisted peritoneal procedure for diagnostic sampling.
    49200Enterectomy, resection of intestine; single resection and anastomosisMay be performed during the same operative session when bowel involvement is found during peritoneal exploration.
    49255Lysis of adhesions (salpingolysis, omentum, peritoneum)Peritoneal adhesiolysis is often performed alongside omental procedures and can be reported when code descriptors match.
    58150Total abdominal hysterectomy (when gynecologic disease is co-managed)Gynecologic procedures may be performed in conjunction with peritoneal/omental procedures for ovarian or uterine pathology.
    49010Exploratory laparotomy, exploratory celiotomy with or without biopsy(s) (separate procedure)Open exploratory approaches that include peritoneal or omental interventions and biopsies; use when a specific code is available, otherwise 49999 may be used.
    32601Thoracotomy, with decortication, for pleural empyema; with or without rib resection (example of nearby body-cavity unlisted work)Included as a related code type to illustrate analogous unlisted or cavity-specific procedures; may be part of multidisciplinary intraoperative management when thoracoabdominal disease spans cavities.

    Related Modifiers

    10 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…
    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…
    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…
    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…
    79Modifier 79 indicates a surgical procedure performed during the postoperative global period of a prior surgery that is unrelated to the original procedure. Per AMA/CPT and CMS guidance, it is…- Use modifier 79 when the same physician (or same‑specialty physician in the same group) performs a surgical procedure during the postoperative global period of a prior surgery and the new procedure…
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    50Modifier –50 (Bilateral Procedure) is appended to a CPT code when an identical procedure is performed on paired anatomical structures during the same operative session. The AMA states to add…- Use modifier -50 when the same CPT surgical, diagnostic, or radiology procedure is performed on paired anatomical structures (both sides of the body) during the same operative/session by the same…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    208100000X
    208000000X
    207K00000X
    2081P0010X
    213ER0200X
    314000000X
    252Y00000X
    163WG0600X

    Related ICD-10-CM Codes

    25 rows

    ICD-10-CM CodeDescription
    A09Infectious gastroenteritis and colitis, unspecified
    B96.89Other specified bacterial agents as the cause of diseases classified elsewhere
    C16.9Malignant neoplasm of stomach, unspecified
    C18.9Malignant neoplasm of colon, unspecified
    C20Malignant neoplasm of rectum
    C45.9Mesothelioma, unspecified
    C78.6Secondary malignant neoplasm of retroperitoneum and peritoneum
    C78.7Secondary malignant neoplasm of liver and intrahepatic bile duct
    K35.80Unspecified acute appendicitis
    K57.00Diverticulitis of small intestine with perforation and abscess without bleeding

    Showing 1–10 of 25

    Related Payer Policy Updates

    Specialty: General Surgery1 / 2

    10 rows

    PolicyPayerEffective Date
    Surgical ProceduresUnitedHealthcare2026-09-01
    Outpatient Surgical Procedures - Site of ServiceUnitedHealthcare2026-09-01
    Site of Service Ambulatory Service Center (ASC) Select — Surgical or Diagnostic Procedures in AdultsPremera Bluecross2026-09-01
    Site of Service Ambulatory Surgical Center (ASC) Select — Surgical or Diagnostic Procedures in AdultsPremera Bluecross2026-09-01
    Site of Service Ambulatory Service Center (ASC) SelectPremera Bluecross2026-09-01
    Site of Service Ambulatory Surgical Center (ASC) Select — Site of Service for Ambulatory Surgical Procedures (ASC Select)Premera Bluecross2026-09-01
    Site of Service Ambulatory Service Center (ASC) SelectPremera Bluecross2026-09-01
    Outpatient Surgical Procedures - Site of Servicesierra health and life2026-08-01
    Medical Necessity Guidelines — Inpatient Surgical CareMass General Brigham Health Plan2026-08-01
    Ambulatory Surgery Center (ASC) - Site of Care PolicyKaiser Permanente2026-08-01

    Related Codes

    CPT-49904-OMENTAL-FLAP-ROTATION-FOR-CHEST-RECONSTRUCTION

    CPT 49904: Omental Flap Rotation for Chest Reconstruction

    CPT-49905-OMENTAL-FLAP-REPOSITIONING-ABDOMINAL-DEFECT

    CPT 49905: Omental Flap Rotation (Omentoplasty) Preserving Vascular Supply

    CPT-49906-OMENTAL-FREE-GRAFT-MICROSURGICAL-RECONSTRUCTION

    CPT 49906: Omentum Free Flap, Microvascular Reconstruction

    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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