CPT Code 00846: Anesthesia for radical hysterectomy and laparoscopy

Key takeaways

CPT Code 00846 covers anesthesia for intraperitoneal procedures in the lower abdomen, including laparoscopy and radical hysterectomy.

The ASA base unit value for 00846 is 8. Time units accrue at one unit per 15-minute interval.

Modifier selection is the most common billing error on this code. The wrong modifier triggers denials and reduces reimbursement.

Practice management software like Pabau captures CPT codes, modifiers, and time units at the point of care, before the claim is built.

CPT Code 00846 covers anesthesia for intraperitoneal procedures in the lower abdomen, including laparoscopy and radical hysterectomy. It carries 8 base units under the ASA Relative Value Guide.

This reference covers the official description, base units, applicable modifiers, Medicare reimbursement calculation, ICD-10 crosswalk, and the billing mistakes that most commonly hit this code.

Where 00846 sits in the anesthesia hierarchy decides the base units you can bill and the codes you must not substitute for it. The sections below cover each element billers and coders need.

CPT Code 00846: Official description and procedures covered

CPT Code 00846 is maintained by the American Medical Association (AMA) as part of the anesthesia section of the CPT code set (range 00100-01999). The official description reads: Anesthesia for intraperitoneal procedures in lower abdomen including laparoscopy; radical hysterectomy.

This code applies when an anesthesia provider delivers services during open or laparoscopic procedures within the lower abdominal peritoneal cavity, specifically including radical hysterectomy. It does not cover upper abdominal intraperitoneal procedures, which fall under different codes in the 00700-00797 series.

The procedures covered under 00846 include both open and laparoscopic radical hysterectomy. Other intraperitoneal lower abdomen procedures qualify too, provided they are not specifically assigned to another anesthesia code. Radical parametrectomy may also fall under this code depending on payer policy and documentation.

Base units and time units for CPT Code 00846

Anesthesia billing uses a units-based reimbursement model rather than a straight fee-for-service rate. Total units for any anesthesia claim combine three components:

• Base units assigned to the code.
• Time units accrued during the procedure.
• Any qualifying circumstance units that apply.

The ASA Relative Value Guide and the CMS anesthesia base unit file both assign CPT Code 00846 a base unit value of 8. Check the current ASA guide and the CMS Physician Fee Schedule for the fiscal year you are billing. CMS sometimes assigns base units that differ from the ASA figure.

Time is documented from the start of anesthesia care to the time the anesthesia provider turns over responsibility. Rounding conventions vary by payer. Some Medicare Administrative Contractors (MACs) round to the nearest 15-minute interval; others use exact minutes converted to fractional units. Confirm the applicable MAC’s policy before submitting.

Precise procedure times are easier to defend when they sit in the patient record rather than a separate log. Structured documentation at the point of care cuts time-unit errors on submission.

Modifiers for CPT Code 00846

Modifier selection is where 00846 claims most frequently go wrong. The modifier signals who performed the anesthesia service and in what role. Payer rules govern which modifiers are recognized, and submitting the wrong one typically results in a denial or reduced payment.

CMS National Correct Coding Initiative (NCCI) edits govern which modifier combinations are valid. Modifier rules are also payer-specific: commercial payers may not recognize the same QK/QX pairing that Medicare accepts. Always verify against the applicable payer’s policy manual before billing.

For practices managing HIPAA-compliant documentation practices alongside anesthesia billing, linking modifier selection to structured encounter documentation reduces the most common submission errors.

Medicare reimbursement for CPT Code 00846

Medicare calculates anesthesia reimbursement using a conversion-factor formula rather than a fixed fee. The formula is: (Base units + Time units + Qualifying circumstance units) x Anesthesia conversion factor = Allowed amount.

The anesthesia conversion factor varies by MAC jurisdiction and is updated annually. Use the FastRVU 2026 RVU lookup or the CMS Physician Fee Schedule to find the current conversion factor for your locality. Never rely on a figure from a prior year without confirming the current rate.

Medical direction under QK typically pays 50% of what a personally performed AA case receives per procedure. The anesthesiologist is splitting billing across multiple concurrent cases. Under the AD supervision modifier, Medicare reimburses only three base units per case, regardless of time. These distinctions make modifier accuracy a direct revenue issue.

ICD-10 codes commonly paired with CPT 00846

Every anesthesia claim requires a supporting diagnosis code that establishes medical necessity. For CPT Code 00846, that code must reflect the documented clinical indication for the procedure. The crosswalk below lists the codes most frequently submitted alongside 00846.

Pick the diagnosis from the operative record rather than from a crosswalk table. A pelvic diagnosis such as O33.2 supports a different procedure set entirely, and pairing it with 00846 will not survive review.

Payer LCD (Local Coverage Determination) policies may impose additional medical necessity requirements for specific diagnoses. Verify each payer’s LCD before submitting, particularly for cases involving benign diagnoses (such as D25.9) where payer pre-authorization may be required for radical procedures.

Related anesthesia CPT codes in the lower abdomen series

Selecting the wrong code from the intraperitoneal lower abdomen anesthesia series is a common miscoding pattern. The codes 00840 through 00848 cover distinct procedures, and the differentiation between them determines correct base unit assignment and reimbursement. Below is the comparison to prevent miscoding between adjacent codes.

The most common miscoding error in this series is billing 00840 instead of 00846 for a radical hysterectomy. That undercodes by 2 units per case, which compounds into a measurable revenue loss across a high volume of gynecological oncology work.

Billing 00848 for a radical hysterectomy that did not involve total pelvic exenteration is the opposite error. Both codes carry 8 base units, so the payment is unchanged. It still misstates the procedure performed and creates audit exposure.

Cross-referencing the operative report against the code description before selection prevents both patterns. Coders working across gynecology apply the same discipline to IVF CPT codes, where procedure detail decides the code.

Billing tips and common errors for CPT Code 00846

Clean claims for CPT Code 00846 depend on four documentation elements. You need the correct procedure code, the correct modifier, accurate time units, and a linked diagnosis code. Missing any one of these creates a denial or a payment reduction. The list below covers the errors that most frequently affect this specific code.

• Wrong modifier for the provider role: Billing AA when the anesthesiologist was directing is a top post-payment audit finding. Confirm the service model on the case before selecting the modifier.
• Incorrect time unit rounding: Some billers round up to the next 15-minute block when the procedure time falls short. Most MACs use specific rounding rules. Document exact start and stop times in the anesthesia record to avoid disputes.
• Missing qualifying circumstances: Add-on units are available under 99100 (extreme age), 99116 (total body hypothermia), and 99135 (controlled hypotension). Radical hysterectomy patients in the geriatric age group may qualify for 99100. Omitting these where the record supports them leaves reimbursement on the table.
• Diagnosis code mismatch: Submitting Z30.2 (sterilization) as the primary diagnosis for a radical hysterectomy performed for malignancy triggers medical necessity flags. The documented clinical indication must drive code selection.
• Concurrent case oversight: Practices billing QK for medical direction must satisfy CMS’s seven required activities for each directed case. Incomplete documentation of those activities converts a QK claim to a supervisory (AD) rate.

Structured HIPAA-compliant billing workflows catch these five patterns before the claim leaves the practice. Claims management software that ties anesthesia time tracking to procedure documentation removes the manual steps where the errors start.

Related CPT codes

• CPT code 00731 — Anesthesia billing for upper GI endoscopy
• CPT Code 00848 — anesthesia for intraperitoneal procedures
• CPT code 00851 — Anesthesia for tubal ligation
• CPT code 00862 — Anesthesia for extraperitoneal procedures

How Pabau supports anesthesia billing documentation

Most 00846 denials trace back to what the anesthesia record failed to capture. Provider role, exact start and stop times, and the linked diagnosis are all settled in the operating room, hours before anyone opens the claim.

Practice management software like Pabau captures CPT codes, modifiers, and procedure times inside the clinical workflow. Nobody has to reconstruct them from memory at billing time. For pelvic health practices handling gynecological oncology cases, linking diagnosis documentation straight to procedure coding removes the crosswalk errors that hit 00846 claims. Auditors read the note before the code, so the documentation level has to support what was submitted. A resubmission does not restart the clock, so the original filing limit still governs.

Encounter records capture anesthesia time, provider role, and procedure type while the case is still open. Modifier and time-unit accuracy becomes a workflow outcome instead of a billing review step.

Pre-procedure records built from digital intake forms support the pre-operative file payers request when they audit medical necessity.

Reduce anesthesia billing errors before they become denials

Pabau’s claims tools help OB/GYN and surgical practices document CPT codes, modifiers, and anesthesia time units at the point of care. Claims leave correctly the first time.

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Conclusion

At 8 base units, CPT Code 00846 sits at the top of the intraperitoneal lower abdomen anesthesia series, tied with 00848. That value reflects the sustained anesthesia management a radical hysterectomy demands. Time units usually outweigh base units on these longer cases, so modifier and time-unit errors carry the largest per-claim cost.

Structured documentation at the point of care is the most reliable way to prevent the five billing errors most common to this code. Pabau’s claims management and encounter documentation tools support that workflow for OB/GYN and surgical practices. Book a demo to see how Pabau can reduce anesthesia billing errors in your practice.

Continue your research

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Billing a procedure with its own modifier traps? CPT code 20606 walks through the units, modifiers, and imaging documentation payers check.

Billing services outside the CPT set? HCPCS code G0299 explains how the Level II code is documented and submitted.

Frequently asked questions