CPT Code 45990: Anorectal exam under anesthesia billing guide

CPT Code 45990 is the billing code for a diagnostic anorectal examination performed under general, spinal, or epidural anesthesia. It applies when a standard office examination cannot complete the evaluation. The code sits in the “Other Procedures on the Colon and Rectum” section of the American Medical Association’s CPT code set.

45990 covers diagnostic exams only. The anesthesia provider bills 00902 separately for the anesthesia itself. The moment the surgeon treats rather than examines, a different code carries the claim.

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Key takeaways

CPT Code 45990 covers a diagnostic anorectal exam under anesthesia and never a therapeutic procedure.

The companion anesthesia code is 00902, billed by the anesthesia provider under their own NPI.

Most 45990 denials trace back to the operative note rather than to the code selection.

2026 Medicare reimbursement varies by facility setting and by locality, so verify rates in the CMS Physician Fee Schedule.

Practice management software like Pabau lets surgical practices attach CPT codes to the procedure note before the claim goes out.

Official descriptor and code classification

CPT Code 45990 describes an anorectal examination, surgical, requiring anesthesia (general, spinal, or epidural), diagnostic. The American Medical Association owns and maintains the code. It is classified under the Surgery section, Digestive System subsection, specifically “Other Procedures on the Colon and Rectum.”

The word “diagnostic” in the descriptor is the part that decides the claim. This code applies only when the anesthetized examination evaluates pathology rather than treats it. Once a therapeutic intervention happens under the same anesthesia, a different procedure code captures that service.

When is CPT Code 45990 used? Clinical indications

CPT Code 45990 applies when a standard office anorectal examination cannot complete the diagnostic evaluation. The attending surgeon decides that anesthesia is medically necessary to examine the anorectal region thoroughly.

Payers require documentation that supports why anesthesia was necessary. The indications below are the ones most commonly accepted, consistent with specialty coding guidance from the American Society of Colon and Rectal Surgeons.

• Patient unable to tolerate office examination due to pain, severe anal spasm, or extreme anxiety
• Suspected fistula-in-ano requiring thorough tract mapping that cannot be completed without anesthesia-facilitated relaxation
• Perianal or anorectal abscess evaluation when the extent and anatomy cannot be adequately assessed in the office
• Rectal prolapse assessment when clinical staging requires examination under anesthesia for accurate determination
• Complex anorectal pathology in patients with prior anorectal surgery, radiation changes, or stricturing disease
• Pediatric patients for whom sedation or anesthesia is required to conduct any anorectal examination safely

This code does not apply when a therapeutic procedure happens at the same time. If a fistulotomy, sphincterotomy, or abscess drainage is performed under the same anesthetic, that therapeutic code replaces or supplements 45990. Check current NCCI bundling edits before billing both on one date.

ICD-10 codes that support medical necessity

Payers require a linked ICD-10-CM diagnosis code that establishes medical necessity for an anorectal exam under anesthesia. The diagnosis must reflect the condition prompting the examination, not the procedure itself. The codes below are the ones Medicare and commercial payers most commonly accept for 45990.

Verify every ICD-10-CM code against the CDC/NCHS ICD-10-CM web tool for the current fiscal year before billing. Payer local coverage determinations may restrict which codes they accept. Our ICD-10-CM code library covers the diagnosis codes that support medical necessity across specialties.

Anesthesia code for CPT 45990: 00902

When a practice bills CPT Code 45990, the anesthesia provider reports the anesthesia service separately under CPT 00902. Its descriptor reads “anesthesia for anorectal procedure.” That is the pairing the ASA and CMS anesthesia crosswalks carry.

Two gastrointestinal endoscopy anesthesia codes, 00812 and 00813, are sometimes quoted for 45990 in error. Neither one describes an anorectal examination, and either will get the anesthesia claim rejected.

The anesthesia code is billed separately from CPT 45990. The surgical team bills 45990, and the anesthesiologist or CRNA bills 00902 under their own National Provider Identifier. Both claims can be submitted electronically through Pabau’s Claim.MD integration, which sends CMS-1500 claims to thousands of US payers.

Medicare fee schedule and RVU breakdown

Medicare reimbursement for CPT Code 45990 is calculated using the Resource-Based Relative Value Scale. Work, practice expense, and malpractice RVUs are each multiplied by a geographic practice cost index. That total is then multiplied by the annual conversion factor to produce the dollar payment.

Use the CMS Physician Fee Schedule Look-Up Tool to retrieve locality-adjusted 2026 rates for your practice ZIP code. National figures are indicative only, because geographic adjustment moves the final number in both directions.

Facility vs non-facility reimbursement rates

Because CPT Code 45990 requires anesthesia, it is always performed in a facility setting. That means a hospital inpatient unit, a hospital outpatient department, or an ambulatory surgery center.

The practice expense RVU is lower in a facility, because the facility absorbs the overhead. Non-facility rates generally do not apply to this code.

Always confirm the place-of-service code on the claim matches the setting where the procedure took place. Mismatched POS codes are a leading cause of reimbursement delays for facility-based anorectal procedures.

Modifiers for an anorectal exam under anesthesia

Modifiers refine the circumstances of the procedure for payers. The modifiers below are the ones most commonly applicable to CPT Code 45990. Append only what accurately reflects the encounter, because incorrect modifier use triggers audits and denials.

Documentation requirements for CPT 45990

Insufficient documentation is the single most common reason CPT Code 45990 claims are denied on audit. The operative note must establish medical necessity and capture every element payers use to adjudicate the claim.

The following elements must appear in the procedure note or anesthesia record:

• Type of anesthesia explicitly documented: general, spinal, or epidural. “Sedation” is not sufficient for CPT 45990.
• Clinical rationale for anesthesia: why office examination was not feasible, such as severe anal spasm preventing a complete exam.
• Diagnostic intent: confirmation that the procedure was performed for diagnostic evaluation, not therapeutic intervention.
• Examination findings: a detailed description of what was seen under anesthesia, including measurements, landmarks, and pathology identified.
• Surgeon’s attestation: the operative note must be signed by the operating surgeon with date and time.
• ICD-10 diagnosis correlation: the documented findings must support the billed ICD-10-CM code or codes.

A standardized procedure note template that prompts for each element above keeps the operative note complete while the surgeon is still writing it. Chasing an addendum after a rejection costs far more time.

Related CPT codes in anorectal and colorectal billing

CPT Code 45990 sits within a broader family of anorectal and colorectal procedure codes. Knowing the adjacent codes prevents unbundling errors and helps coders pick correctly when a therapeutic procedure is also performed. Cross-reference the codes below against current NCCI edits before billing more than one on the same date.

The decision that matters is what the surgeon did once the patient was asleep. The diagram below maps that single choice onto the three codes it can lead to.

Common billing errors and how to avoid them

Denials for CPT Code 45990 cluster around five recurring errors. Each one is preventable with the right documentation habits and claim review process. Strong claim denial management catches these before submission rather than after the fact.

• Missing anesthesia type in the operative note. The CPT descriptor specifies general, spinal, or epidural anesthesia. A note reading “monitored anesthesia care” or “IV sedation” will be denied. Document the exact anesthesia type used.
• Incorrect place-of-service code. CPT 45990 is a facility procedure. Billing it under POS 11 triggers an automatic edit, because an anesthesia-requiring procedure cannot happen in an office. Confirm the POS code before submission.
• Billing 45990 when a therapeutic procedure was performed. Once the surgeon intervenes therapeutically under the same anesthetic, the diagnostic code is no longer primary. The therapeutic code takes precedence. Code what the surgeon performed, not what was planned.
• Weak ICD-10-CM pairing. Payers match the diagnosis code against the procedure to confirm medical necessity. An unspecified code without supporting detail flags the claim. Use the most specific code the operative findings support.
• Unbundling errors. Some anorectal procedure codes are bundled with 45990 under NCCI edits. Billing both without modifier 59, or an XS modifier where appropriate, results in denial. Check the edits before billing two anorectal codes on one date.

How Pabau supports anorectal procedure billing workflows

Practices billing CPT Code 45990 carry documentation pressure at every stage. The operative note has to capture specific clinical elements, and the claim has to pair the right ICD-10 code. The submission then has to clear NCCI edits before it reaches the payer.

Pabau’s claims software for surgeons connects those steps in one workflow.

Colorectal and surgical practices using Pabau can build procedure note templates that prompt for anesthesia type, diagnostic rationale, and examination findings. The prompts appear while the surgeon is writing the note. CPT and ICD-10 codes attach to that note before the claim is submitted.

The platform then routes the claim electronically through its Claim.MD integration, which sends CMS-1500 claims to thousands of US payers. Validation runs before the claim leaves the practice, so errors surface while they are still cheap to fix.

Streamline anorectal procedure billing from documentation to payment

Pabau helps colorectal and surgical practices attach CPT codes to procedure notes at the point of care. Claims go out electronically, and denials are tracked in the same place. See how it works for your practice.

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Conclusion

CPT Code 45990 rests on a simple judgment. If the surgeon only examined, 45990 is the claim. If the surgeon also treated, the therapeutic code carries the claim instead.

Almost every 45990 denial comes down to what the operative note says, not to which code was picked. Build the required elements into your procedure note template, verify the ICD-10 pairing before submission, and check NCCI edits on same-day claims.

Do that consistently and 45990 denials stop being a monthly surprise. Book a demo to see how Pabau keeps the operative note, the codes, and the claim in one place.

Continue your research

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