CPT code 44145 – Partial colectomy with coloproctostomy (low pelvic anastomosis)

Key takeaways

CPT 44145 is an open partial colectomy with coloproctostomy, a low anterior resection that reconnects the remaining colon to the rectum.

No stoma belongs to 44145. Adding a colostomy makes it 44146, and closing the rectal stump with an end colostomy makes it 44143.

The laparoscopic counterpart is 44207, not 44204, which is the laparoscopic version of 44140.

The operative note must state the open approach, the segment removed, and an anastomosis to the rectum low in the pelvis.

Report add-on 44139 with 44145 when the surgeon documents splenic flexure mobilization.

CPT code 44145: Official description and procedure overview

CPT code 44145 reports an open partial colectomy in which the surgeon removes part of the colon and reconnects the remaining colon to the rectum. The American Medical Association publishes it in the CPT code set. The official descriptor reads: Colectomy, partial; with coloproctostomy (low pelvic anastomosis).

Surgeons and coders usually call this operation a low anterior resection. The coloproctostomy is the defining element. The surgeon joins the colon to the rectum deep in the pelvis, which restores bowel continuity in the same operation. The descriptor includes no colostomy.

Typical indications include sigmoid and rectosigmoid cancer, upper and mid rectal cancer, and complicated diverticular disease of the sigmoid colon. Large benign rectal polyps that can’t be removed endoscopically are another. The open approach separates 44145 from its laparoscopic counterpart, 44207.

Procedure breakdown: What the surgeon does under CPT 44145

A low anterior resection coded under 44145 follows a defined operative sequence. Each step should appear in the operative note to support the code.

1. Open access: The surgeon enters the abdomen through a laparotomy, usually a lower midline incision.
2. Mobilization: The sigmoid and descending colon are mobilized, and the inferior mesenteric vessels are ligated and divided. When the colon needs extra length to reach the pelvis, the splenic flexure is taken down as well.
3. Resection: The diseased segment is removed together with the upper part of the rectum. For rectal cancer, the resection usually includes a total or partial mesorectal excision.
4. Coloproctostomy: The remaining colon is joined to the rectal stump low in the pelvis, most often with a circular stapler. The join may be end-to-end, side-to-end, or a colonic J-pouch.
5. Leak test and closure: The anastomosis is commonly tested for leaks before the abdominal wall is closed in layers.

The critical distinction is that continuity is restored and no colostomy is made. If the surgeon also creates a colostomy, the correct code is 44146. If the rectal stump is closed and an end colostomy is brought out, the operation is a Hartmann procedure, coded 44143.

Surgeons often protect a low anastomosis with a temporary loop ileostomy. The 44145 descriptor does not describe one. Check current NCCI edits and the payer’s policy before reporting an ileostomy code on the same claim.

CPT 44145 vs 44140 to 44147: How to choose the right code

The 44140 to 44147 family covers open partial colectomy. Two questions separate the codes. Where was the colon joined, if at all? And was a stoma created?

Read the table from the anastomosis column first. A join to the rectum points to 44145, 44146 or 44147, and a stoma then decides between 44145 and 44146.

CPT 44145 vs 44207: Open vs laparoscopic low anterior resection

CPT 44207 is the laparoscopic counterpart of 44145. Its descriptor reads: Laparoscopy, surgical; colectomy, partial, with anastomosis, with coloproctostomy (low pelvic anastomosis). Robotic-assisted cases are coded as laparoscopic, so they map to 44207 as well.

A common error is reaching for 44204 on a laparoscopic low anterior resection. CPT 44204 is the laparoscopic version of 44140, which describes a colon-to-colon anastomosis.

When a laparoscopic case converts to open, report the open code, 44145, and do not report the laparoscopic attempt. If the conversion added substantial work, some payers accept modifier 22 with operative note support.

Add-on 44139: Splenic flexure mobilization

A low anastomosis often needs the splenic flexure taken down so the colon reaches the pelvis without tension. Report add-on code 44139 with 44145 when the operative note documents that mobilization.

In a laparoscopic case, the matching add-on is 44213 with 44207. The matrix below puts the open and laparoscopic codes side by side, add-ons included.

ICD-10-CM diagnosis codes commonly paired with CPT 44145

Every 44145 claim needs at least one ICD-10-CM code that establishes medical necessity for the resection and the low pelvic anastomosis. The diagnosis must appear in the operative note, not only in the admission record.

Use the most specific ICD-10-CM code available. For colorectal malignancy, report the primary tumor site, so a tumor at the rectosigmoid junction takes C19 rather than C20.

Payers with local coverage determinations (LCDs) cross-reference the diagnosis against covered indications. A non-covered code paired with 44145 can deny however well the operative note is written. The CrossCoder CPT-to-ICD-10 crosswalk tool helps verify which diagnosis codes support 44145 under payer-specific LCDs.

Documentation requirements: What the operative note must include

For clean claim submission on a 44145, the operative note must document every element the descriptor requires. Missing any of the following creates an audit vulnerability.

• Open surgical approach: State that the procedure was performed through an open laparotomy. Without an approach statement, an auditor can’t tell 44145 from 44207.
• Extent of colonic resection: Name the segment removed, such as the sigmoid colon and upper rectum, and record the proximal and distal margins.
• Level and type of anastomosis: Document that the colon was joined to the rectum low in the pelvis, and record the technique. A colon-to-colon join above the rectum supports 44140 instead.
• Stoma status: State that no colostomy was created, because a colostomy changes the code to 44146. Document any diverting ileostomy separately, with its own indication.
• Abdominal approach only: Confirm the resection was done from the abdomen. A combined abdominal and transanal approach is reported with 44147.
• Splenic flexure mobilization: If the surgeon took down the splenic flexure, record it so add-on 44139 can be reported.
• Surgeon attestation and signature: The operative report must be authenticated by the operating surgeon, per CMS documentation standards.

Per AHIMA guidelines, the coder should query the surgeon when the note is unclear about the anastomosis or a stoma. Coding from an ambiguous note without a query is a compliance risk.

Modifiers for CPT code 44145

Several modifiers apply to CPT 44145, depending on the operative circumstances and billing scenario. Each carries specific documentation requirements.

CPT 44145 carries a 90-day global surgical period under Medicare as a major surgical procedure. Routine post-operative visits within that window are included in the global payment. A return to the operating room for a complication is billed with modifier 78, and an unrelated procedure with modifier 79.

Medicare reimbursement and RVUs for CPT 44145

CPT 44145 carries high relative value units, reflecting the operative time and complexity of an open pelvic resection and anastomosis. Pabau, the practice management platform we build, sends professional claims through Claim.MD, its US clearinghouse integration. It supports CMS-1500 and 837P submission.

Medicare updates the Physician Fee Schedule every January 1. Always verify current RVU values and payment rates with the CMS MPFS look-up tool rather than cached figures from prior years. The FastRVU 2026 RVU lookup gives a quick reference for the work, practice expense, and malpractice components.

Professional payment is separate from the facility DRG payment the hospital receives for the inpatient stay. Keep the two apart when estimating practice revenue.

The superbill documentation for 44145 should capture the procedure date, the surgeon’s NPI, and the place of service code. It should also list every applicable ICD-10-CM code before the claim is generated.

Prior authorization requirements for CPT 44145

Prior authorization norms for 44145 vary by payer type and urgency.

• Commercial payers: Most require prior authorization for an elective open low anterior resection. Submit the diagnosis, imaging such as the staging CT or MRI, the operative plan, and any failed non-surgical management.
• Traditional Medicare: Medicare generally requires no prior authorization for the inpatient stay or the surgeon’s professional claim. Medicare Advantage plans often do, under their own policies.
• Emergency procedures: Payers generally waive prior authorization for emergency surgery. Document the emergent indication clearly in the operative note and admission records.
• Medicaid: Requirements vary by state. Check the state Medicaid provider manual before scheduling an elective case.

When authorization is required, the package typically includes the diagnosis with supporting imaging and the surgeon’s attestation of medical necessity. It also covers non-surgical management that was tried or contraindicated, and the proposed code, 44145, with the planned date of service.

Common claim denial reasons for CPT 44145 and how to avoid them

Most denials on 44145 claims fall into seven categories. Each one traces back to the operative note, the diagnosis, or a missing authorization.

1. A Hartmann procedure billed as 44145: When the rectal stump is closed and an end colostomy is created, no coloproctostomy exists. That operation is 44143, so confirm an anastomosis to the rectum before assigning 44145.
2. A colostomy created but 44145 billed: A low anterior resection with a colostomy is 44146. Billing 44145 plus a separate colostomy code invites a bundling denial.
3. Approach doesn’t match the code: A laparoscopic or robotic resection is 44207, not 44145. On the laparoscopic side, 44204 is wrong for a low pelvic anastomosis.
4. Anastomosis level not documented: A note that says “anastomosis” without naming the rectum supports only 44140. Obtain a surgeon addendum before submitting.
5. Diagnosis code does not support medical necessity: A non-specific or unrelated ICD-10-CM code fails payer LCD review. Use the most specific code for the pathology in the op note.
6. Prior authorization not obtained for an elective case: Commercial denials for missing authorization are rarely overturned on clinical grounds. Prevention is the only dependable remedy.
7. Modifier 22 without supporting documentation: Most payers want a letter describing the complicating factors when modifier 22 is appended. Without it, the additional payment is denied.

When a 44145 claim is denied, check the denial codes on the ERA before appealing. CARC 4 (procedure code inconsistent with the modifier) and CARC 97 (payment included in another service) are common surgical denials. Coders can often resolve both with documentation or rebilling.

Coding tips and billing best practices for CPT 44145

Accurate 44145 coding starts with a line-by-line read of the operative report. Use the AAPC CPT code lookup to cross-check the descriptor and adjacent parenthetical notes before finalizing the code.

• Code from the anatomy, not the label: Surgeons use “low anterior resection” loosely. Code from what the note describes, including the anastomosis level, any stoma, and the approach.
• Read the operative note in sequence: The procedure header sometimes lists the intended operation. The body of the note may describe a different one after intraoperative findings.
• Check AMA parenthetical notes: The CPT code book carries parenthetical notes near 44145 that clarify what is separately reportable. Review them before adding secondary codes.
• Verify NCCI edits before submitting: NCCI edits update quarterly, so check every code billed with 44145 against the current tables. An edit with modifier indicator 1 can be bypassed with the right modifier, but indicator 0 cannot.
• Query before coding, not after denial: Per AHIMA physician query guidelines, query the surgeon when the note is unclear about the anastomosis or a stoma. A pre-submission query is more persuasive than one attached to an appeal.
• Hold unsigned notes: An operative note without the surgeon’s authentication is not a codeable document. Hold the claim until the note is signed.

How claims management software prevents 44145 denials

Without claims software, a coder checks each 44145 claim by hand against the op note. They confirm the approach, the anastomosis level and the stoma status, then key the claim into a separate clearinghouse portal. A missing authorization number often surfaces only when the denial arrives.

Pabau runs those checks inside its claims management software. Claim validation scrubs each claim for missing or invalid details before submission and flags any claim missing an authorization code. In the US, eligibility checks run through Claim.MD, and ERA files can be settled when the payer responds.

Your coder still decides between 44145, 44146 and 44207. What changes is that an incomplete claim stops before submission, so it gets fixed before the payer sees it.

Catch colorectal claim errors before the payer does

Pabau checks each claim for missing or invalid details before submission, and US eligibility checks run through Claim.MD. Fewer avoidable denials reach your billing team.

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Conclusion

Accurate coding of CPT 44145 rests on one operative fact. The surgeon removed part of the colon and joined what remained to the rectum, without a colostomy.

That fact separates 44145 from a Hartmann procedure (44143) and from a resection protected by a colostomy (44146). The approach then separates it from laparoscopic 44207. Build a pre-submission check around those three questions, and add 44139 whenever the note documents splenic flexure mobilization.

Book a demo to see how Pabau flags incomplete surgical claims before they reach the payer.

Continue your research

Need to understand how clearinghouse edits catch errors before submission? Our Claim.MD clearinghouse guide explains how real-time eligibility checks and claim edits work for surgical procedures.

Looking for guidance on denial codes and how to respond? Understanding electronic remittance advice covers how to read CARC and RARC codes on ERAs from surgical claim submissions.

Want a step-by-step breakdown of the medical billing cycle for surgical practices? What is revenue cycle management walks through each stage from charge capture through payment posting.

Coding a laparoscopic colon-to-colon resection instead? CPT code 44204 covers the laparoscopic partial colectomy with anastomosis that coders often confuse with 44207.

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