CPT® Code 49905

Quick Reference: CPT 49905

• Full Descriptor: Omental flap, intra-abdominal (List separately in addition to code for primary procedure)
• Code Type: Add-on code (+) — must always be reported alongside a primary surgical procedure code. Never reported as a standalone code.
• What It Describes: Mobilization and repositioning of a vascularized pedicle flap of omentum to fill or cover a defect within the abdominal cavity, without disrupting its blood supply.
• Primary Procedure Restriction: None. Per AMA CPT Assistant, 49905 may be reported in addition to any primary procedure in which an intra-abdominal omental flap is used.
• Open vs. Laparoscopic: May be reported for both open and laparoscopic surgical approaches.
• Critical Distinction: Do not use 49905 for simple anastomosis buttressing — only for true defect reconstruction requiring deliberate omental mobilization.
• Key Related Codes: 49904 (extra-abdominal omental flap), 49906 (free omental flap with microvascular anastomosis), 49326 (laparoscopic omentopexy, add-on).
• Global Period: As an add-on code, 49905 does not carry an independent global period — it follows the primary procedure’s global package.
• Medicare: Listed on the Medicare Physician Fee Schedule (MPFS); reimbursable, though local MAC coverage determinations apply.

CPT 49905 captures one of the most clinically significant reconstructive maneuvers performed during abdominal surgery: the deliberate mobilization of the greater omentum — a fatty, richly vascularized apron of peritoneum — and its transposition to fill a defect, protect a vulnerable anastomosis site, reinforce a repair, or obliterate dead space within the abdominal or pelvic cavity.

The omentum is uniquely suited for this purpose. It carries a robust blood supply via the gastroepiploic arcade, produces angiogenic growth factors, and is capable of walling off infection and promoting neovascularization. These biological properties make omental flaps indispensable in complex abdominal surgery — and because the work of deliberate omental mobilization and repositioning extends substantially beyond any inherent closure maneuver, the AMA created 49905 to allow separate capture of this service.

Despite its utility, CPT 49905 is one of the most frequently denied add-on codes in abdominal surgery billing. Payers routinely bundle it into the primary procedure, and coders often misapply it to procedures where the omentum is merely “tucked” around an anastomosis rather than formally mobilized and transposed as a reconstructive flap. This guide provides the clinical, coding, and documentation guidance necessary to report 49905 correctly — and to defend it under audit or on appeal.

Anatomy & Clinical Role of the Omental Flap

The greater omentum is a double-layered fold of peritoneum that hangs from the greater curvature of the stomach and drapes over the small and large intestines like an apron. It receives its blood supply primarily from the right and left gastroepiploic arteries, branches of the gastroduodenal and splenic arteries, respectively. This dual-artery inflow allows surgeons to base a pedicle flap off either side while preserving viability.

Clinically, the omentum serves as a natural “first responder” — it migrates toward sites of inflammation, infection, or ischemia within the peritoneal cavity. Surgeons leverage this property in a number of high-stakes scenarios:

• Defect coverage after radical resection: Following cystectomy, pelvic exenteration, or Whipple procedure, the omentum is mobilized to fill the resulting dead space, reducing the risk of abscess formation and bowel obstruction from adhesions.
• Reinforcement of high-risk anastomoses: In cases where a bowel anastomosis is at elevated risk for leak — due to radiation, malnutrition, or prior sepsis — a formal omental pedicle flap (not mere tucking) may be wrapped around the anastomosis as a reconstructive maneuver.
• Fistula management and repair: The omentum is used to interpose between two fistulizing organs (e.g., enterovaginal, colovesical) to obliterate the fistula tract and promote tissue healing.
• Vascular graft coverage: In aortobifemoral bypass or aortic reconstruction, an omental pedicle flap may be tunneled retroperitoneally to separate the prosthetic graft from the adjacent duodenum, preventing the devastating complication of an aorto-enteric fistula.
• Pelvic floor reconstruction: Following pelvic exenteration (CPT 58240) or other radical gynecologic-oncologic surgery, an omental “J-flap” is fashioned and placed into the pelvis to prevent small bowel from settling into the radiation field or empty pelvic cavity, dramatically reducing the incidence of radiation-induced bowel obstruction.

Code Descriptor, Add-On Rules & AMA Guidance

The official AMA CPT descriptor for 49905 is:

“Omental flap, intra-abdominal (List separately in addition to code for primary procedure)”

The “+” designation makes 49905 a true add-on code. Under AMA rules, add-on codes are never subject to multiple procedure reduction (Modifier 51 does not apply), are never reported as standalone codes, and are exempt from the multiple procedure payment reduction that CMS applies to secondary procedures under the MPFS.

Critical AMA Clarification (CPT Assistant, November 2000; reaffirmed by AAPC): An early version of the 49905 descriptor referenced “reconstruction of sternal and chest wall defects,” which led to widespread confusion about whether the code was limited to those applications. The AMA has explicitly clarified that the parenthetical examples in any code descriptor are illustrative, not restrictive. CPT 49905 may be reported in addition to any primary procedure in which an intra-abdominal omental flap is performed. There is no published list of approved primary procedure pairings for this add-on code.

Open vs. Laparoscopic Approach

A common misconception — reinforced by an older AAPC Knowledge Center article — is that 49905 applies only to open surgical procedures. The AMA has clarified that because the code descriptor does not specify an approach, and because the clinical work (deliberate mobilization and transposition of the omentum) can be accomplished laparoscopically, CPT 49905 may be reported in addition to a laparoscopic primary procedure when the omental flap is performed as a distinct, documented service. As with all laparoscopic add-on work, the documentation must clearly describe the laparoscopic mobilization and placement of the omental flap.

Eligible Primary Procedure Codes

Because there is no official restricted list of primary codes for 49905, the following represents the most common, real-world primary procedure pairings encountered in surgical coding. In each case, the operative note must clearly document that a distinct omental flap — not routine omental manipulation — was performed.

Payer Bundling Alert: Some Medicare Administrative Contractors and commercial payers have generated automatic bundling edits that deny 49905 when billed with certain primary codes (e.g., 44145, 44150) on the grounds that “omental wrap” is inherent to the primary procedure. This is often incorrect when the operative note documents a formal, deliberate omental mobilization and transposition rather than incidental omental use. Modifier 59 (or XS/XU as appropriate) and a detailed operative note are the key to overturning these denials.

flowchart TD
    A[Omentum used during surgery] --> B{Was the omentum deliberately mobilized?}
    B -->|No - merely tucked or rearranged| C[Do NOT report 49905]
    B -->|Yes| D{Was a vascular pedicle identified and preserved?}
    D -->|No| C
    D -->|Yes| E{Was the flap transposed to a new location?}
    E -->|No| C
    E -->|Yes| F{Where was the flap placed?}
    F -->|Intra-abdominal| G[CPT 49905 - Add-on code]
    F -->|Extra-abdominal / chest wall| H[CPT 49904 - Standalone]
    F -->|Free flap with microvascular anastomosis| I[CPT 49906 - Standalone]

Critical Distinction: When NOT to Report 49905

This is the single most important section for preventing audit exposure and maintaining coding compliance. CPT 49905 requires a distinct surgical service — deliberate omental mobilization and transposition as a reconstructive flap. It does not apply to any of the following, which are considered inherent components of the primary procedure:

• Anastomosis buttressing: Using a small fold of adjacent omentum or mesenteric fat to reinforce a freshly created intestinal anastomosis (e.g., after colectomy) is considered a standard technical step, inherent to the anastomosis creation. Per KZA (Karen Zupko & Associates) guidance, this is not separately reportable with 49905.
• Incidental omental placement: If the surgeon simply “tucks” or positions a loop of omentum over a repair without deliberate mobilization of a flap from its attachments, this does not constitute an omental flap procedure.
• Fibrin sealant or hemostatic agent coverage: Applying hemostatic agents or sealants to the omentum, or using the omentum as a surface to hold such agents, is not separately billable.
• Omentectomy: Removal of the omentum (CPT 49255) is a distinct service from omental flap creation. These may both be performed in the same case, but 49905 applies only to the flap creation, not to omental excision.
• Laparoscopic omentopexy (49326): Tacking the omentum to prevent internal herniation — for example, in laparoscopic sleeve gastrectomy — is captured by CPT 49326, another add-on code, not 49905. Do not use both codes for the same anatomic maneuver.

Documentation Test: Ask this question before reporting 49905: “Did the surgeon deliberately mobilize a segment of omentum from its native position — with specific attention to preserving or identifying its vascular pedicle — and then transpose it to a location it would not otherwise reach, for the purpose of reconstruction or filling a defect?” If the answer is yes, 49905 is appropriate. If the omentum was merely rearranged or tucked, the code is not supported.

Audit-Proof Documentation Standards

Because 49905 is frequently targeted in payer audits and RAC reviews, operative note documentation must be explicit and unambiguous. Vague or boilerplate language such as “omentum was placed over the repair” will not support a separate charge and is the primary reason this code is denied or recouped.

Required Documentation Elements

• Identification of the flap’s vascular pedicle: The note should name the supplying vessel (e.g., “right gastroepiploic artery,” “left gastroepiploic artery”) and confirm it was preserved throughout the mobilization.
• Description of the mobilization: Document the extent of omental dissection from its attachments. For example: “The greater omentum was mobilized from the transverse colon, developing the omentum off the mesocolon over a distance of approximately 15 cm, based on the right gastroepiploic pedicle.”
• Description of transposition and inset: Describe how and where the flap was placed, and how it was secured. For example: “The omental flap was then transposed into the pelvis and secured with interrupted 2-0 Vicryl sutures to the sacral promontory and sidewall fascia, obliterating the pelvic dead space.”
• Clinical indication: Document the medical necessity for the omental flap separately from the primary procedure indication. For example: “Given the patient’s prior pelvic radiation and the anticipated pelvic dead space following exenteration, an omental J-flap was fashioned to prevent bowel obstruction and fistula formation.”
• Distinction from primary procedure work: If the primary procedure is a colectomy with anastomosis, the operative note must make clear that the omental flap was a separate, additional step beyond the colectomy and anastomosis, and that it was not simply a routine anastomosis wrap.

Sample Operative Note Language That Supports 49905

Correct: “Following completion of the low anterior resection and stapled colorectal anastomosis, attention was turned to fashioning an omental flap for pelvic reinforcement. The greater omentum was mobilized from the transverse colon mesentery, preserving the right gastroepiploic arcade. The omental pedicle was developed to a length sufficient to reach the deep pelvis. The flap was tunneled posterior to the mesocolon and secured to the pelvic peritoneum with four interrupted 3-0 Vicryl sutures, covering the anastomosis circumferentially. This constituted a separately planned and executed intra-abdominal omental flap reconstruction due to the patient’s prior radiation history and elevated anastomotic leak risk.”

Incorrect (does not support 49905): “The anastomosis was reinforced with omentum.” or “Omentum was wrapped around the anastomosis.”

ICD-10-CM Diagnosis Code Pairings

CPT 49905 must be paired with ICD-10-CM diagnosis codes that establish the medical necessity for the omental flap — specifically, a diagnosis that explains why defect coverage, dead-space obliteration, or reinforcement was required. The following are the most commonly encountered and payer-accepted pairings:

Always ensure that the diagnosis code reflects the patient’s specific documented condition — never use unspecified codes when more specific codes are available and supported by the documentation. CMS and commercial payers increasingly reject unspecified codes when the clinical record supports greater specificity.

Medicare Coverage, MPFS & Denial Patterns

CPT 49905 is listed on the Medicare Physician Fee Schedule (MPFS) and is reimbursable by Medicare Part B for physician services. Because it is an add-on code, CMS does not apply the standard multiple procedure payment reduction (Modifier 51 is not appended and should not be used). As an add-on code, 49905 also carries a 0-day global period in the context of the add-on, meaning no post-operative care is separately bundled into the add-on fee — all post-operative management is captured in the primary procedure’s global period.

NCCI (National Correct Coding Initiative) Edits

Per AAPC coding discussions, there are no hard NCCI Procedure-to-Procedure (PTP) edits bundling 49905 into the most common primary procedure codes such as 49560 (hernia repair) or 44150 (colectomy). This means that when properly documented, 49905 can be reported alongside these codes without a modifier to override a CCI edit — though commercial payers may still apply their own proprietary bundling logic that differs from CCI.

Common Denial Patterns and How to Address Them:

• Denial Reason: “Procedure included in primary procedure.” Response: Submit Modifier 59 (or XU — Unusual Non-Overlapping Service) with the claim, along with the relevant operative note pages that specifically document the omental flap mobilization as a distinct surgical step. Cite CPT Assistant (November 2000) confirming that 49905 may be reported in addition to any primary procedure in which an omental flap is used.
• Denial Reason: “Medical necessity not established.” Response: Ensure the claim includes an ICD-10 code that directly supports the need for omental flap reconstruction (e.g., K65.0 peritonitis, C67.9 bladder malignancy). Attach a letter of medical necessity from the operating surgeon explaining the clinical indication for the omental flap as a distinct reconstructive maneuver.
• Denial Reason: “Code not covered for laparoscopic procedure.” Response: Per AMA CPT Assistant guidance, 49905 is not restricted to open procedures. Submit the AAPC Knowledge Center article (April 2019) by John Verhovshek, CPC, confirming that 49905 may be reported in addition to laparoscopic primary procedures when the omental flap is performed as a distinct, documented service.
• Denial Reason: “Duplicate code / included in colectomy.” Response: Distinguish the omental flap (49905) from incidental omental wrapping. Provide the operative note demonstrating deliberate pedicle development and transposition, and clarify that the colectomy code does not include a separately performed omental flap.

Place of Service Considerations

CPT 49905 is a major surgical add-on code performed exclusively in the inpatient hospital or ambulatory surgical center (ASC) setting. It is never performed in an office setting. The Place of Service (POS) code will be 21 (Inpatient Hospital), 22 (On-Campus Outpatient Hospital), or 24 (ASC), depending on where the primary procedure is performed. Ensure the POS on the claim matches the facility billing.

Modifier Usage

Modifier 22 — Increased Procedural Services

If the omental flap mobilization was substantially more complex than typically required — for example, in a patient with extensive prior abdominal surgeries, dense adhesions, or a massively enlarged or atrophic omentum requiring creative vascular dissection — Modifier 22 may be appended to 49905. This modifier signals to the payer that the work was significantly greater than standard and requests enhanced reimbursement. A letter of medical necessity from the surgeon, along with detailed operative note documentation of the unusual challenges, is required. Expect a payer review before payment is released.

Modifier 51 — Multiple Procedures

Do NOT use Modifier 51 with CPT 49905. As a designated add-on code, 49905 is inherently exempt from multiple procedure reduction. Appending Modifier 51 is incorrect and may result in inappropriate payment reduction or denial.

Modifier 59 — Distinct Procedural Service

Modifier 59 (or its more specific X{EPSU} subsets) is the most important modifier in the 49905 billing toolkit. It is used when a payer’s bundling logic incorrectly bundles 49905 into the primary procedure, or when a payer denies 49905 on the grounds that it is “included” in the primary surgical service. Modifier 59 identifies 49905 as a distinct service not ordinarily encountered on the same day, supported by separate documentation. Always confirm that the operative note contains language clearly distinguishing the omental flap as a separate, additional step.

The preferred X modifier subsets under CMS policy are: XU (Unusual Non-Overlapping Service) — most applicable here, since omental flap reconstruction does not overlap with the work of colectomy, cystectomy, or other primary procedures.

Modifier 62 — Two Surgeons (Co-Surgeons)

In some complex cases — particularly pelvic exenterations or complex aortic reconstructions performed by a multidisciplinary team — an omental flap may be fashioned by one surgeon (e.g., a gynecologic oncologist or general surgeon) while another surgeon performs the primary procedure. In such cases, Modifier 62 may be used by both surgeons if each documents their distinct role. Each surgeon bills the same code(s) with Modifier 62, and payment is typically split at 62.5% per surgeon. The operative note from each surgeon must separately document their individual contributions.

Modifier GC — Teaching Physician

In academic medical centers where a resident participates in the omental flap component of the procedure, the teaching physician must document their presence and direct supervision during the critical portions of the omental flap mobilization and inset. Modifier GC is appended to certify that the teaching physician was present and participated appropriately.

Code Comparison: 49904 vs. 49905 vs. 49906 vs. 49326

The critical decision point between 49904 and 49905 is the destination of the omental flap: extra-abdominal (outside the peritoneal cavity) = 49904; intra-abdominal (within the peritoneal cavity) = 49905. The distinction between 49905 and 49906 is even more clinically important: 49905 is a pedicle flap (blood supply preserved and continuous), while 49906 is a free flap (blood supply divided and reanastomosed by a microvascular surgeon at the recipient site). Confusing these two codes is a significant coding error with major reimbursement and compliance implications.

Complex Clinical Coding Scenarios

Scenario 1: Perforated Duodenal Ulcer with Graham Patch

Patient: 58-year-old male presents with acute abdomen. Imaging reveals free air. Taken to OR emergently for perforated duodenal ulcer.

Operative Findings: 8mm anterior duodenal perforation. Peritoneal contamination with gastric contents.

Procedure: Perforation closed with interrupted sutures (primary repair). A tongue of greater omentum was then mobilized off the transverse colon, preserving the right gastroepiploic pedicle over a 12 cm length. The omental pedicle was transposed to the duodenum and secured over the primary repair with four interrupted 3-0 Vicryl sutures to reinforce the closure and provide vascular support (Graham patch technique with formal pedicle mobilization).

Coding: 43840 (Suture of perforated gastric/duodenal wound) + 49905 (Omental flap, intra-abdominal)

ICD-10: K26.1 (Duodenal ulcer, acute with perforation)

Rationale: The omental pedicle was formally mobilized and deliberately transposed and secured — this is not routine wound closure. The operative note documents pedicle development, specific length, and suture fixation. 49905 is appropriate and defensible.

Scenario 2: Total Pelvic Exenteration with Omental J-Flap

Patient: 63-year-old female with locally advanced cervical cancer, status post prior pelvic radiation. Undergoing total pelvic exenteration.

Procedure: Total pelvic exenteration completed. Following resection, the pelvis contained a large dead space with scarred, irradiated tissue. The greater omentum was mobilized from the transverse colon based on the right gastroepiploic artery, fashioned into a J-shaped pedicle flap, and placed into the pelvis. The flap was secured with interrupted absorbable sutures to the sacral periosteum and bilateral pelvic sidewalls, completely obliterating the pelvic dead space and creating a barrier to prevent small bowel from entering the pelvis.

Coding: 58240 (Pelvic exenteration) + 49905 (Omental flap, intra-abdominal)

ICD-10: C53.9 (Malignant neoplasm of cervix uteri, unspecified) + Z85.41 (Personal history of malignant neoplasm of cervix uteri, if prior)

Rationale: SGO coding guidance explicitly identifies the omental pedicle J-flap as separately reportable with 49905 in addition to pelvic exenteration (58240). This is one of the clearest supported applications of this add-on code. Document the J-flap creation, pedicle identification, and pelvic inset explicitly in the operative note.

Scenario 3: Whipple Procedure with Omental Wrap of Pancreatic Anastomosis

Patient: 71-year-old male with pancreatic head adenocarcinoma. Pancreaticoduodenectomy (Whipple) performed. Soft pancreatic texture noted; elevated leak risk.

Procedure: Whipple procedure completed. Given the soft pancreatic texture and dilated pancreatic duct (high-risk anastomosis), the surgeon mobilized a segment of the greater omentum, developing a pedicle based on the right gastroepiploic artery. The omental pedicle was brought up and wrapped circumferentially around the pancreaticojejunostomy, then secured with interrupted 3-0 Vicryl sutures to provide vascular reinforcement and reduce fistula risk.

Coding: 48150 (Pancreaticoduodenectomy, Whipple) + 49905

ICD-10: C25.0 (Malignant neoplasm of head of pancreas)

Rationale: The omental wrap was deliberately fashioned with a named vascular pedicle and secured with sutures — not a routine anastomosis tuck. Documentation clearly distinguishes this from incidental omental placement. Expect possible payer denial requiring Modifier XU and appeal; the operative note is the cornerstone of success.

Scenario 4: Aortobifemoral Bypass with Retroperitoneal Omental Transposition

Patient: 67-year-old male undergoing aortobifemoral bypass for aortoiliac occlusive disease. Intraoperatively, the retroperitoneal tissue was insufficient to separate the prosthetic graft from the duodenum.

Procedure: Aortobifemoral bypass completed (35646). Retroperitoneal closure was inadequate to prevent graft-duodenum contact. A large omental pedicle flap was mobilized off the transverse colon utilizing the left gastroepiploic artery as inflow. The flap was tunneled through a retrocolic window in the mid-transverse colon mesentery into the retroperitoneum and secured over the aortobifemoral bypass graft with interrupted Vicryl sutures, effectively separating the graft from the duodenum.

Coding: 35646 (Bypass graft, aortobifemoral) + 49905 (Omental flap, intra-abdominal)

ICD-10: I74.09 (Embolism and thrombosis of aorta) or I70.0 (Atherosclerosis of aorta)

Rationale: This is a classic application of 49905 in vascular surgery. The omental flap prevents the catastrophic complication of aorto-enteric fistula, which carries a mortality rate exceeding 50%. The pedicle identification (left gastroepiploic artery), tunneling maneuver, and suture fixation are well-documented in the operative note and clearly exceed routine closure work.

Scenario 5: Scenario Where 49905 Is NOT Appropriate — Colectomy with Anastomosis

Patient: 55-year-old female undergoing laparoscopic left colectomy with primary anastomosis for sigmoid colon cancer.

Operative Note Language: “The anastomosis was reinforced with omentum.”

Coding Decision: Do NOT report 49905.

Rationale: This single sentence documents incidental omental placement, not a formally mobilized omental pedicle flap. There is no documentation of pedicle development, length of mobilization, named vascular supply, or deliberate transposition. Per KZA and AAPC guidance, buttressing an anastomosis with adjacent omental fat is inherent to the primary procedure and is not separately reportable. Billing 49905 in this scenario constitutes overcoding and creates audit exposure.

Denial Management & Appeal Strategies

Given the frequency with which 49905 is denied, a proactive appeals workflow is essential for any surgical practice or hospital coding department that regularly uses this code. The following strategies have the highest success rates:

• Pre-submission documentation review: Before submitting any claim containing 49905, a certified surgical coder should review the operative note to confirm that the five documentation elements (pedicle identification, mobilization extent, transposition description, inset with sutures, and separate clinical indication) are all present. Claims missing these elements should be held until an addendum or clarification note is obtained from the surgeon.
• First-level appeal — Operative note with annotation: Submit the relevant pages of the operative note with highlighting or marginal annotations identifying the specific language that describes the omental flap as a distinct reconstructive step. Include a cover letter citing CPT Assistant (November 2000) and the AMA’s clarification that 49905 is not restricted to any specific primary procedure.
• Second-level appeal — Physician letter of medical necessity: If the first-level appeal fails, submit a letter from the operating surgeon explaining the clinical rationale for the omental flap as a distinct service, the specific technique used, and why it was medically necessary and not inherent to the primary procedure.
• External peer-to-peer review: For high-dollar denials, request a peer-to-peer discussion between the operating surgeon and the payer’s medical director. In complex reconstructive cases, most surgical specialists can persuasively distinguish deliberate omental flap reconstruction from routine anastomosis management.
• Track denial patterns by payer: Maintain a log of which payers consistently deny 49905 and with which primary codes. If a payer consistently bundles 49905 into a specific primary code without clinical basis, escalate to contract renegotiation or formal dispute resolution through the payer’s provider relations department.