CPT code 00866: Adrenalectomy anesthesia billing guide

Key Takeaways

CPT code 00866 covers anesthesia for an adrenalectomy, not urologic or gynecologic surgery; it sits in the 00800-00882 extraperitoneal lower-abdomen range alongside kidney, bladder, and prostate codes.

The base unit value for CPT code 00866 is 10. Reimbursement is (base units + time units) x conversion factor; the finalized 2026 CMS national anesthesia conversion factor is $20.4976 per unit.

Modifier AD (medical supervision of more than four concurrent cases) pays a flat 3 base units with no time units added, plus at most 1 extra unit if the physician documents presence at induction.

Practice management software like Pabau can help anesthesia billing teams track base units, modifiers, and documentation across adrenal and other extraperitoneal procedures, reducing denied claims.

CPT code 00866 is the anesthesia code for an adrenalectomy, open or laparoscopic removal of one or both adrenal glands. It sits in the 00800-00882 lower-abdomen range alongside several urology codes, though it isn’t a urology code itself, and no surgeon bills it directly.

Its base unit value is 10, among the highest in that family. Handling the adrenal gland can flood the bloodstream with catecholamines and swing blood pressure in both directions. That’s exactly why the anesthesia team has to stay ahead of it for the whole case.

What CPT code 00866 actually covers

CPT code 00866’s full descriptor reads: “Anesthesia for extraperitoneal procedures in lower abdomen, including urinary tract; adrenalectomy.” The “including urinary tract” phrase isn’t an error. It reflects how CPT structures this entire code family.

The AMA’s CPT code set defines a shared parent stem under CPT 00860, and 00866 is one of several child entries under that stem, specific to adrenalectomy.

The code covers anesthesia for removing one or both adrenal glands, through either an open or laparoscopic approach. It doesn’t cover kidney, bladder, or prostate surgery, and the surgeon never bills it. As an anesthesia-only code, it never appears on the surgical claim. The surgical team bills a separate CPT code for the operation itself.

The adrenal glands sit above the kidneys, in the retroperitoneum. CPT still classifies adrenalectomy anesthesia inside the 00800-00882 lower-abdomen range, the same range that covers kidney, bladder, ureter, and prostate anesthesia.

The grouping reflects shared surgical positioning and exposure, not strict anatomic height. Coders looking for a separate adrenal-specific range elsewhere in the anesthesia section won’t find one. 00866 is it.

Base units for CPT code 00866, and how it compares to nearby codes

Every anesthesia CPT code carries a fixed base unit value, set independent of how long the case runs. For CPT code 00866, that value is 10 units. Base units reflect the complexity and risk of the anesthesia service itself, not the surgeon’s incision or technique.

The table below places 00866 next to the other codes in its family, plus the intraperitoneal code most often confused with it:

00866 and 00868 (renal transplant recipient) share the highest base unit value in the family, 10 units. Both involve physiologic instability beyond routine extraperitoneal surgery. Adrenal manipulation can trigger catecholamine surges, and transplant recipients carry immunosuppression and fluid-shift risk. 00862 (renal procedures) and 00865 (radical prostatectomy) sit lower, at 7 units, reflecting more routine anesthesia management.

Confirm the current-year value against the CPT codebook or the CMS Physician Fee Schedule lookup tool before billing. Base units are reviewed periodically.

How to calculate reimbursement for CPT code 00866

Anesthesia reimbursement does not use a flat fee. It follows a formula: (Base Units + Time Units) x Conversion Factor = Reimbursement.

Time units accrue at one unit per 15 minutes of anesthesia time, calculated to one decimal place when the minutes don’t divide evenly. Anesthesia time starts when the provider begins preparing the patient and ends when the provider is no longer in personal attendance.

Here’s a worked example using the finalized 2026 CMS national anesthesia conversion factor of $20.4976 per unit:

This is the Medicare formula. Commercial payers negotiate their own conversion factors, often higher, and Medicare applies a geographic locality multiplier on top of the national rate. A high-cost locality pays more per unit than a rural one for the identical case.

Confirm locality-specific rates through CMS’s fee schedule lookup rather than relying on national averages for billing submissions.

Common procedures billed under CPT code 00866

CPT code 00866 applies whenever the surgical target is the adrenal gland, regardless of the surgical approach. The anesthesia code does not change between open and laparoscopic surgery. Only the surgeon’s procedure code does. Procedures anesthetized under 00866 include:

• Open adrenalectomy (transabdominal, lumbar, or dorsal approach): surgeon bills CPT 60540.
• Open adrenalectomy with excision of an adjacent retroperitoneal tumor: surgeon bills CPT 60545.
• Laparoscopic adrenalectomy: surgeon bills CPT 60650, now the more common approach for most benign and small malignant adrenal tumors.
• Bilateral adrenalectomy, for conditions such as bilateral pheochromocytoma or ectopic ACTH-driven Cushing’s syndrome, billed with modifier 50 (bilateral procedure) on the surgical claim.
• Partial (cortical-sparing) adrenalectomy, used in select hereditary pheochromocytoma cases to preserve some adrenal function.

CPT code 00866 is an anesthesia-only code. It never substitutes for the surgeon’s CPT code, and it never appears on the surgical claim.

Practices billing both sides of an adrenalectomy case need two linked claims: the anesthesia claim carries 00866, the correct modifier, and time units, while the surgical claim carries 60540, 60545, or 60650. Keeping those two claims connected matters for surgical and cosmetic surgery practices alike, since a mismatch between them is a common source of denials.

Modifiers for CPT code 00866, and where AD trips people up

Anesthesia modifiers identify who delivered the service and under what provider arrangement. Medicare and most commercial payers require one on every anesthesia claim. Submitting without a modifier, or applying the wrong one, causes immediate denial.

The modifier determines what percentage of the calculated reimbursement the billing provider receives:

Modifier AA: anesthesiologist personally performs the service

Modifier AA applies when the anesthesiologist is present throughout the case and personally administers the anesthesia, with no CRNA involved. Under Medicare, AA pays 100% of the allowed amount. The record must show continuous personal attendance, not just availability nearby.

Modifiers QX, QY, QZ, and QK for CRNA and medical direction billing

QX and QY are mirror modifiers: the CRNA’s claim carries QX, the anesthesiologist’s claim carries QY, when a physician medically directs one CRNA for one case. Both bill at 50%, totaling 100% of the Medicare rate split between two providers. QK covers an anesthesiologist directing two to four concurrent procedures. Each corresponding CRNA claim carries QX.

QZ applies where a CRNA works without physician direction, commonly in states that have opted out of the Medicare physician supervision requirement, and it pays 100% of the allowed amount. State opt-out status can change, so confirm current status directly with your Medicare Administrative Contractor before assuming it applies.

Modifier AD: what supervision actually pays

AD is the modifier billing teams misjudge most often. It applies when an anesthesiologist medically supervises more than four concurrent procedures, a lower level of oversight than medical direction.

In that arrangement, Medicare pays a flat 3 base units for the case. No time units apply, no matter how long the procedure ran. Medicare adds at most 1 further unit, and only if the anesthesiologist documents personal presence at induction.

For CPT code 00866, modifier AA totals 16 units: 10 base plus 6 time. Under AD, the same case pays out at only 3, or at most 4, units.

At the 2026 conversion factor, that is roughly $61 to $82, not $275 or more. This rule sits in 42 CFR 414.46(f) and the Medicare Claims Processing Manual, Chapter 12, Section 50. Confusing AD with QK, which pays 50% of the allowed amount plus time units, is a costly and avoidable error in either direction.

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Medicare reimbursement rates for CPT code 00866 in 2025 and 2026

Medicare calculates CPT code 00866 reimbursement using the base unit formula above, adjusted by the anesthesia conversion factor and the geographic locality multiplier. The figures below are national averages. Use the CMS Physician Fee Schedule lookup tool for the exact rate in your area before submitting claims.

Both figures are the standard rate that applies to most physicians. CMS finalized a second, slightly higher 2026 rate of $20.5998 for clinicians who qualify as Advanced Alternative Payment Model participants. Confirm your practice’s APM status before assuming which rate applies.

Geographic locality adjustments can shift reimbursement 10 to 30 percent above or below the national average. Use CMS’s fee schedule lookup for locality-adjusted estimates before forecasting revenue from CPT code 00866 cases.

ICD-10 codes that support medical necessity for CPT code 00866

Accurate ICD-10 pairing is essential for medical necessity. Medicare Local Coverage Determinations (LCDs) govern which ICD-10 codes support coverage for anesthesia billed under CPT code 00866. Submitting without a supported diagnosis code triggers automatic denial. Each surgical indication driving the adrenalectomy needs a matching ICD-10 code on the claim.

The table below lists ICD-10 codes commonly paired with CPT code 00866. All are billable, terminal-level codes. The parent categories they sit under (C74.0, C74.1, D35.0, E26.0) are not valid for billing on their own. Each requires one of these more specific child codes.

Verify companion ICD-10 codes against current LCDs for your Medicare Administrative Contractor (MAC) jurisdiction, since coverage policies vary by MAC. The CMS ICD-10 codes page lists current coding guidelines and annual update files.

Many of these hormone-secreting conditions, including Cushing’s and Conn’s syndrome, first surface through an endocrine workup at a primary care or functional medicine practice, well before the patient reaches the operating room.

Common billing mistakes with CPT code 00866

Billing errors on anesthesia claims draw some of the closest payer scrutiny. These are the mistakes that show up most often on CPT code 00866 claims:

• Missing modifier: every anesthesia claim needs a provider-role modifier. No modifier means automatic denial.
• Miscounting time units: Medicare converts anesthesia minutes into fractional time units, minutes divided by 15, to one decimal place, rather than rounding down to a whole unit. A 92-minute case is 6.1 time units, not 6, bringing CPT code 00866 to 16.1 total units (10 base plus 6.1 time). Some commercial payers use different increments or round differently, so check the payer contract before assuming Medicare’s method applies.
• Confusing 00866 with a neighboring code: if the operative note shows the kidney, not the adrenal gland, was the target, the correct code is 00862, not 00866. Query the surgeon when the note is ambiguous about which organ was removed.
• Billing AD as if it pays like QK: AD pays a flat 3 base units with no time units added; QK pays 50% of the allowed amount plus time units. Treating them as equivalent causes a significant over- or underpayment.
• Reporting AA when the case was medically directed: AA pays 100% of the allowed amount; QX/QY (medical direction) each pay 50%. The HHS Office of Inspector General has reviewed this exact pattern in anesthesia audits, since the wrong modifier means Medicare pays more than the arrangement supports.

What the anesthesia record must document

Anesthesia records must satisfy both AMA documentation standards and CMS Conditions of Participation. An incomplete record isn’t just a compliance risk. It’s the primary defense document if a claim is audited. For CPT code 00866, the record should include:

• Pre-anesthesia evaluation: history, physical exam, ASA physical status, airway assessment, and, for a suspected pheochromocytoma, relevant biochemical workup (catecholamine, cortisol, or aldosterone levels) and alpha-blockade status. Complete before induction.
• Anesthesia start and stop times: recorded to the minute, from the start of patient preparation to the end of personal attendance.
• Intraoperative monitoring record: vital signs at a documented interval; for pheochromocytoma cases, continuous invasive blood pressure monitoring is standard practice given the risk of catecholamine surges during tumor handling.
• Anesthetic agents administered: drug, dose, route, and time for every agent used.
• Personnel identification: name and credential of every provider present, with role clearly stated, directly supporting modifier selection.
• Hemodynamic recovery note: blood pressure trend after the adrenal gland is removed, since catecholamine withdrawal can cause a sharp drop that needs prompt management.
• Post-anesthesia note: completed within 48 hours, documenting patient status, vital signs at transfer, complications, and follow-up plan.

Using digital documentation tools that timestamp entries automatically reduces the risk of reconstructed records, a common audit finding in anesthesia billing.

Related CPT codes in the 00860 family

CPT code 00866 belongs to the 00860 family: extraperitoneal lower-abdomen procedures involving the urinary tract, the adrenal gland, or a kidney transplant. Related codes in that family include:

• CPT 00860: the parent, not-otherwise-specified code for the family; 6 base units.
• CPT 00862: renal procedures, including the upper one-third of the ureter, or donor nephrectomy; 7 base units.
• CPT 00864: total cystectomy; 8 base units.
• CPT 00865: radical prostatectomy (suprapubic, retropubic); 7 base units.
• CPT 00868: renal transplant recipient; 10 base units, tied with 00866 for the highest in the family.
• CPT 00870: cystolithotomy; 5 base units.

Two adjacent codes are easy to confuse with 00866 but sit in different families entirely. CPT 00840 covers intraperitoneal, not extraperitoneal, lower-abdomen procedures, so use it when the surgical approach enters the peritoneal cavity. CPT 00902 covers anorectal procedures in the separate Perineum section (00902-00952), distinct from the 00800-00882 lower-abdomen range 00866 belongs to.

Anesthesia CPT codes extend well beyond the 00860 family, too. CPT 00812 covers screening colonoscopy, and CPT 00625 covers thoracic spine surgery, both a world away from adrenal or urologic cases.

CPT 00920, for male genital procedures, sits in that same wider set. Whichever family a case falls into, consult the operative note, and query the surgeon if it’s ambiguous, before choosing a code.

How Pabau supports anesthesia billing workflows

Anesthesia billing involves time-sensitive data collection, provider-role tracking, and modifier accuracy across high volumes of surgical cases. Most billing errors trace back to clinical and billing workflows that don’t talk to each other.

Pabau’s claims management software helps anesthesia billing teams reduce errors. It centralizes procedure code tracking, flags incomplete documentation before submission, and keeps a structured audit trail for each case. When the clinical record links to the billing workflow, time-unit data, modifier assignments, and ICD-10 pairings get captured at the point of care rather than reconstructed afterward.

Surgical practices already running on practice management software can integrate claims workflows into the same system. That cuts down on the double-entry errors that happen when anesthesia records live apart from the billing platform.

Pabau’s automated billing workflows can route adrenal and other extraperitoneal cases through a documentation checklist before submission, adding a review layer without extra manual work.

Three checks that get CPT code 00866 right

Confirm the adrenal gland, not the kidney or prostate, was the surgical target. Apply the modifier that matches the provider arrangement, not just the one used last time. Document time and monitoring at the point of care, not after the fact.

Practice management software like Pabau can help surgical and anesthesia billing teams keep that documentation connected to the claim, so modifier selection and time units stay traceable before a claim reaches the payer. Book a demo to see how Pabau supports anesthesia billing workflows.

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