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CPT 45112: Rectal Resection with Colonic Anastomosis to Anus

CPT code 45112 represents a combined abdominal and perineal resection of the rectum with colonic anastomosis to the anus, most commonly performed for rectal cancer to preserve normal defecation. Nationally, this code captures a major inpatient colorectal surgery that has implications for hospital resources, surgical quality measures, and payer reimbursement policies. It is relevant to surgical oncology, colorectal surgery programs, and inpatient surgical administrators.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical intent of the procedure, typical care settings, and the reasons the code matters for case mix, utilization, and quality reporting. The publication also summarizes common billing modifiers associated with this service and points to related clinical and coding considerations.

The report provides benchmarks and context for utilization and reimbursement trends where available, summarizes relevant policy updates that affect coverage and prior authorization practices, and outlines clinical context for billing and coding teams. Data not available in the input is noted where appropriate.

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Billing Code Overview

CPT code 45112 describes a surgical procedure in which the provider removes the rectum and anastomoses the colon to the anus using both an abdominal and perineal approach. The procedure is typically performed to treat rectal cancer and is intended to preserve an uninterrupted digestive tract so the patient can pass stool normally.

Service type: Abdominoperineal colorectal resection with restoration of intestinal continuity (combined abdominal and perineal surgical procedure)
Typical site of service: Inpatient surgical setting (operating room with pre- and post-operative inpatient care)

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CPT 45112: Rectal Resection with Colonic Anastomosis to Anus

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Billing Code Overview

Service type: Abdominoperineal colorectal resection with restoration of intestinal continuity (combined abdominal and perineal surgical procedure)
Typical site of service: Inpatient surgical setting (operating room with pre- and post-operative inpatient care)

Clinical & Coding Specifications

Clinical Context

A 62-year-old patient with a biopsy-proven mid-rectal adenocarcinoma presents after staging that shows a resectable tumor without distant metastases. The multidisciplinary team recommends an abdominoperineal resection with coloanal anastomosis (procedure 45112) to achieve oncologic resection while preserving bowel continuity. Preoperative workup includes colonoscopy, pelvic MRI, CT chest/abdomen/pelvis, cardiopulmonary clearance, and discussion of bowel preparation and perioperative antibiotics. The operative workflow begins with an abdominal phase to mobilize the left colon and ligate vascular pedicles, followed by a perineal phase to excise the rectum and perform a hand-sewn or stapled coloanal anastomosis. Intraoperative documentation includes indication (rectal cancer), tumor location and extent, margins, estimated blood loss, drains placed, specimen description, intraoperative complications, and disposition. Typical post-operative care includes monitoring in a surgical ward or intensive care setting as appropriate, pain control, DVT prophylaxis, early ambulation, assessment of anastomotic integrity, and coordination for adjuvant oncology if indicated. Typical site of service is an inpatient acute care hospital. Service type is a major surgical procedure (open/invasive abdominal and perineal resection) performed by colorectal or general surgeons with colorectal specialization.

Coding Specifications

Modifier	Description	When to Use
`00`	No modifier; standard reporting	Use when no special circumstances apply and the service is reported as usual.
`11`	Office/Outpatient/Other E/M - usually not used for surgery but listed in modifier set	Rarely applicable; not used for the operative claim for `45112`.
`22`	Increased procedural services	Use when work, time, or complexity substantially exceeds typical expectations and documentation supports the increased work.
`23`	Unusual anesthesia	Use when general anesthesia is not used because of severe circumstances and documentation supports use of unusual anesthesia circumstances.
`26`	Professional component	Use only if reporting a separate professional component distinct from a global surgical service (rare for this procedure).
`50`	Bilateral procedure	Not typically applicable; use if truly bilateral anatomic work is reported and payer allows.
`51`	Multiple procedures	Use when `45112` is reported on the same day along with other distinct procedures; report to identify multiple procedure reduction.
`52`	Reduced services	Use when the procedure is intentionally partially reduced or not completed as described.
`53`	Discontinued procedure	Use when the procedure is started but discontinued for reasons not related to patient choice; requires documentation.
`62`	Two surgeons	Use when two surgeons work together as primary surgeons performing distinct portions of the procedure.
`63`	Procedure performed on infants <4 kg	Use only if patient meets age/weight criteria (rare for this procedure).
`66`	Surgical team (multiple surgeons)	Use when an integrated team performs the procedure and payer accepts the modifier.
`78`	Unplanned return to OR after initial procedure	Use if patient requires an unplanned return to the operating room for a related procedure during the global period.
`79`	Unrelated procedure or service during global period	Use when an additional unrelated procedure is performed during the global period.
`80`	Assistant surgeon	Use when an assistant at surgery (resident or another surgeon) participates and assistant fees are paid.

Taxonomy Code	Specialty	Notes
207L00000X	Colon and Rectal Surgery	Colorectal surgeons most commonly perform `45112`.
207N00000X	General Surgery	General surgeons with colorectal expertise perform this procedure in many hospitals.
208000000X	Surgery	Surgical oncologists or abdominal surgeons may perform related resections.
207K00000X	Gastroenterology Surgery (if applicable)	Occasionally involved for perioperative endoscopic management; not primary operator.
2084P0800X	Surgical Oncology	Involvement when cancer-directed surgical expertise is required.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C20`	Malignant neoplasm of rectum	Primary indication for `45112`; rectal adenocarcinoma requiring resection.
`C21.8`	Malignant neoplasm of overlapping sites of anus and rectum	Tumors involving rectum and adjacent anorectal regions that may require combined approaches.
`C19`	Malignant neoplasm of rectosigmoid junction	Tumors at the rectosigmoid may require low rectal resection with coloanal anastomosis depending on location.
`D01.0`	Carcinoma in situ of rectosigmoid junction	High-grade dysplasia or carcinoma in situ that might prompt surgical resection in select cases.
`K62.5`	Anal fissure and fistula (chronic)	Not a primary indication for `45112` but may be documented as comorbidity affecting perineal dissection; included as commonly co-encountered anorectal pathology.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`44145`	Colectomy, partial; total abdominal colectomy with ileorectal anastomosis	May be performed when extended colonic resection is required or for synchronous disease during the same hospitalization.
`44204`	Laparoscopy, surgical; colectomy, partial, with anastomosis	Minimally invasive alternative for colon mobilization in selected cases prior to perineal phase or as combined approach.
`45378`	Colonoscopy, flexible; diagnostic, with or without collection of specimen	Preoperative diagnostic and surveillance colonoscopy to localize tumor and obtain biopsies.
`38531`	Biopsy or excision of lymph nodes (e.g., intra-abdominal)	Lymph node sampling may accompany oncologic resection for staging.
`49020`	Exploration, peritoneal cavity, for tumor resection (laparotomy)	Related to abdominal exploration and tumor debulking that can be part of the operative plan.
`99152`	Moderate sedation services provided by the same physician or other qualified health care professional	May be reported for procedures requiring monitored sedation when billing rules permit (use depends on payer policy).

CPT 45100: Anal Approach Biopsy of Anorectal Wall

CPT-45108-ANORECTAL-TUMOR-EXCISION

CPT 45108: Excision of Anorectal Muscle Tumor

CPT-45110-ABDOMINOPERINEAL-RESECTION-WITH-COLOSTOMY

CPT 45110: Abdominoperineal Resection with Colostomy

CPT-45111-PARTIAL-RECTAL-RESECTION-ABDOMINAL-APPROACH

CPT 45111: Partial Rectal Resection, Abdominal Approach

CPT-45113-PROCTECTOMY-ILEOANAL-ANASTOMOSIS-ILEAL-POUCH

CPT 45113: Partial Proctectomy with Ileoanal Anastomosis and Ileal Pouch

CPT-45114-RECTAL-RESECTION-ANASTOMOSIS-ABDOMINAL-SACRAL-APPROACH

CPT 45114: Rectal Resection and Colon-Rectal Anastomosis, Abdominal and Sacral Approach

CPT-45116-POSTERIOR-APPROACH-RECTAL-RESECTION-ANASTOMOSIS

CPT 45116: Posterior Rectal Resection with Colorectal Anastomosis

CPT-45119-RESTORATIVE-PROCTOCOLECTOMY-WITH-COLONIC-POUCH

CPT 45119: Restorative Proctocolectomy with Colonic Pouch

CPT-45120-ABDOMINOPERINEAL-RECTAL-RESECTION-COLON-ANASTOMOSIS

CPT 45120: Abdominoperineal Rectal Resection with Colon-Anus Anastomosis

CPT-45121-PULL-THROUGH-RESECTION-ABDOMINAL-PERINEAL-COLORECTAL-ANASTOMOSIS

CPT 45121: Pull-Through Resection with Colorectal Anastomosis

Showing 1–10 of 19

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`00`	No modifier; standard reporting	Use when no special circumstances apply and the service is reported as usual.
`11`	Office/Outpatient/Other E/M - usually not used for surgery but listed in modifier set	Rarely applicable; not used for the operative claim for `45112`.
`22`	Increased procedural services	Use when work, time, or complexity substantially exceeds typical expectations and documentation supports the increased work.
`23`	Unusual anesthesia	Use when general anesthesia is not used because of severe circumstances and documentation supports use of unusual anesthesia circumstances.
`26`	Professional component	Use only if reporting a separate professional component distinct from a global surgical service (rare for this procedure).
`50`	Bilateral procedure	Not typically applicable; use if truly bilateral anatomic work is reported and payer allows.
`51`	Multiple procedures	Use when `45112` is reported on the same day along with other distinct procedures; report to identify multiple procedure reduction.
`52`	Reduced services	Use when the procedure is intentionally partially reduced or not completed as described.
`53`	Discontinued procedure	Use when the procedure is started but discontinued for reasons not related to patient choice; requires documentation.
`62`	Two surgeons	Use when two surgeons work together as primary surgeons performing distinct portions of the procedure.
`63`	Procedure performed on infants <4 kg	Use only if patient meets age/weight criteria (rare for this procedure).
`66`	Surgical team (multiple surgeons)	Use when an integrated team performs the procedure and payer accepts the modifier.
`78`	Unplanned return to OR after initial procedure	Use if patient requires an unplanned return to the operating room for a related procedure during the global period.
`79`	Unrelated procedure or service during global period	Use when an additional unrelated procedure is performed during the global period.
`80`	Assistant surgeon	Use when an assistant at surgery (resident or another surgeon) participates and assistant fees are paid.

Taxonomy Code	Specialty	Notes
207L00000X	Colon and Rectal Surgery	Colorectal surgeons most commonly perform `45112`.
207N00000X	General Surgery	General surgeons with colorectal expertise perform this procedure in many hospitals.
208000000X	Surgery	Surgical oncologists or abdominal surgeons may perform related resections.
207K00000X	Gastroenterology Surgery (if applicable)	Occasionally involved for perioperative endoscopic management; not primary operator.
2084P0800X	Surgical Oncology	Involvement when cancer-directed surgical expertise is required.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C20`	Malignant neoplasm of rectum	Primary indication for `45112`; rectal adenocarcinoma requiring resection.
`C21.8`	Malignant neoplasm of overlapping sites of anus and rectum	Tumors involving rectum and adjacent anorectal regions that may require combined approaches.
`C19`	Malignant neoplasm of rectosigmoid junction	Tumors at the rectosigmoid may require low rectal resection with coloanal anastomosis depending on location.
`D01.0`	Carcinoma in situ of rectosigmoid junction	High-grade dysplasia or carcinoma in situ that might prompt surgical resection in select cases.
`K62.5`	Anal fissure and fistula (chronic)	Not a primary indication for `45112` but may be documented as comorbidity affecting perineal dissection; included as commonly co-encountered anorectal pathology.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`44145`	Colectomy, partial; total abdominal colectomy with ileorectal anastomosis	May be performed when extended colonic resection is required or for synchronous disease during the same hospitalization.
`44204`	Laparoscopy, surgical; colectomy, partial, with anastomosis	Minimally invasive alternative for colon mobilization in selected cases prior to perineal phase or as combined approach.
`45378`	Colonoscopy, flexible; diagnostic, with or without collection of specimen	Preoperative diagnostic and surveillance colonoscopy to localize tumor and obtain biopsies.
`38531`	Biopsy or excision of lymph nodes (e.g., intra-abdominal)	Lymph node sampling may accompany oncologic resection for staging.
`49020`	Exploration, peritoneal cavity, for tumor resection (laparotomy)	Related to abdominal exploration and tumor debulking that can be part of the operative plan.
`99152`	Moderate sedation services provided by the same physician or other qualified health care professional	May be reported for procedures requiring monitored sedation when billing rules permit (use depends on payer policy).

CPT 45100: Anal Approach Biopsy of Anorectal Wall

CPT-45108-ANORECTAL-TUMOR-EXCISION

CPT 45108: Excision of Anorectal Muscle Tumor

CPT-45110-ABDOMINOPERINEAL-RESECTION-WITH-COLOSTOMY

CPT 45110: Abdominoperineal Resection with Colostomy

CPT-45111-PARTIAL-RECTAL-RESECTION-ABDOMINAL-APPROACH

CPT 45111: Partial Rectal Resection, Abdominal Approach

CPT-45113-PROCTECTOMY-ILEOANAL-ANASTOMOSIS-ILEAL-POUCH

CPT 45113: Partial Proctectomy with Ileoanal Anastomosis and Ileal Pouch

CPT-45114-RECTAL-RESECTION-ANASTOMOSIS-ABDOMINAL-SACRAL-APPROACH

CPT 45114: Rectal Resection and Colon-Rectal Anastomosis, Abdominal and Sacral Approach

CPT-45116-POSTERIOR-APPROACH-RECTAL-RESECTION-ANASTOMOSIS

CPT 45116: Posterior Rectal Resection with Colorectal Anastomosis

CPT-45119-RESTORATIVE-PROCTOCOLECTOMY-WITH-COLONIC-POUCH

CPT 45119: Restorative Proctocolectomy with Colonic Pouch

CPT-45120-ABDOMINOPERINEAL-RECTAL-RESECTION-COLON-ANASTOMOSIS

CPT 45120: Abdominoperineal Rectal Resection with Colon-Anus Anastomosis

CPT-45121-PULL-THROUGH-RESECTION-ABDOMINAL-PERINEAL-COLORECTAL-ANASTOMOSIS

CPT 45121: Pull-Through Resection with Colorectal Anastomosis

Showing 1–10 of 19

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

OpenPayer

CPT 45112: Rectal Resection with Colonic Anastomosis to Anus

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Billing Code Overview

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CPT 45112: Rectal Resection with Colonic Anastomosis to Anus

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References