CPT code 01120: Bony pelvis anesthesia billing guide

Key Takeaways

CPT code 01120 covers anesthesia for procedures on the bony pelvis, the ilium, ischium, pubis, sacrum, and coccyx. It excludes the hip joint and the femur.

The ASA-assigned base unit value for CPT 01120 is 6, not 7. Reimbursement uses (Base Units + Time Units + Modifying Units) x Conversion Factor.

Hip joint anesthesia bills under a separate code family, 01200–01214, with 01214 covering total hip arthroplasty specifically.

Pabau’s claims management tools help practices match base units, modifiers, and time to the procedure actually documented, for codes like 01120.

CPT code 01120 gets mixed up with hip surgery more often than almost any other anesthesia code. A biller sees the word pelvis on the operative note, assumes it means hip joint, and bills the wrong base units. That one assumption is enough to knock a clean claim into a denial queue.

The truth is simpler than the confusion around it. CPT 01120 covers anesthesia for the bony pelvis, the ilium, ischium, pubis, sacrum, and coccyx, and it excludes the hip joint and the femur entirely. Get that boundary straight, and the rest of the claim, base units, modifiers, and diagnosis pairing, falls into place.

What CPT code 01120 actually covers

CPT code 01120 is the anesthesia code for procedures on the bony pelvis. The American Medical Association (AMA) maintains the CPT code set. It places 01120 in the Anesthesia for Procedures on the Pelvis (Except Hip) family, a group of codes running from 01112 through 01173. That parenthetical, except hip, is doing a lot of work. It tells you upfront that this code family was built to exclude the hip joint.

Bony pelvis means the ilium, ischium, pubis, sacrum, and coccyx, the ring of bone connecting the spine to the legs. It does not mean the hip joint, and it does not mean the femur. Procedures billed under 01120 typically include open or percutaneous fixation of pelvic fractures that do not involve the acetabulum. Other examples are biopsy or tumor work on a pelvic bone, and iliac bone graft harvest for use elsewhere in the body.

How the 6 base units turn into a payment

Anesthesia billing does not work like most CPT codes. Instead of one flat fee per service, the American Society of Anesthesiologists (ASA) assigns a base unit value to each anesthesia code. It then adds time and modifying units on top. For CPT 01120, the base unit value is 6. Confirm that figure against the current ASA Relative Value Guide (RVG) before you submit, since values are reviewed periodically.

The formula itself, published in the CMS Medicare Physician Fee Schedule, stays the same across every anesthesia code:

Total units = Base Units (B) + Time Units (T) + Modifying Units (M)

Reimbursement = Total Units x Anesthesia Conversion Factor (CF)

Medicare counts time in 15-minute increments, starting when the anesthesia provider begins preparing the patient and ending when they are no longer in personal attendance. A 120-minute case works out to 8 time units.

Worked example: ORIF of a pelvic fracture under CPT 01120

Here is how a full claim adds up for open reduction and internal fixation (ORIF) of an iliac fracture. It is a 120-minute case on a P3 patient (severe systemic disease, common after trauma), using an illustrative conversion factor of $20.50. Medicare’s actual conversion factor changes annually and commercial payer rates vary, so treat this CF as an example only.

Commercial payers rarely use Medicare’s conversion factor. Check your contract or payer portal for the actual rate before estimating reimbursement on a specific claim.

Medicare’s anesthesia conversion factor also shifts by geography. A practice in a high-cost metro area sits under a different locality adjustment than one in a rural county, even for an identical CPT 01120 claim. The CMS Physician Fee Schedule lookup tool filters by MAC locality, so pull the exact rate for your billing address rather than reusing last year’s figure.

Trauma cases billed under 01120, like emergent pelvic fracture fixation, typically do not need prior authorization the way an elective pelvic tumor resection might. Check payer policy by procedure type, not just by CPT code, since urgency changes the authorization pathway.

Where 01120 sits among the pelvis and hip anesthesia codes

01120 is one code in a small family that covers the pelvis, sitting right next to a completely separate family that covers the hip joint. Mixing the two up is the single most common error on these claims, so it is worth seeing them side by side.

The pelvis code family, from bone marrow biopsy to hindquarter amputation

Every code in the 01112–01173 range shares one thing: none of them touch the hip joint or the femur. What changes is the specific pelvic procedure. CPT code 01112, for example, covers a much narrower scenario, a bone marrow aspiration or biopsy at the iliac crest.

Two more codes round out the family. CPT code 01160 covers closed procedures on the symphysis pubis or sacroiliac joint at 4 base units. CPT 01170 covers the open version of the same procedures at 8 base units.

CPT 01173, at 12 base units, is reserved for open repair of a pelvic ring disruption or an acetabular column fracture. That is a step up in complexity from a standard 01120 case. And for tumor work, CPT code 01150 covers radical pelvic tumor procedures that fall short of a hindquarter amputation.

Why hip joint anesthesia needs a different code entirely

The hip joint has its own family of anesthesia codes, and none of them are 01120. If the operative report says hip arthroplasty, hip disarticulation, or a closed hip procedure, look here instead.

Total hip arthroplasty (THA) bills under CPT code 01214, not 01120. That single distinction is the one this article exists to correct, so flag it for anyone on your team who learned it the other way. CPT code 01200 covers the closed-procedure counterpart when the hip joint is treated without an open incision.

ICD-10 codes that justify a bony pelvis anesthesia claim

CPT 01120 needs a diagnosis code that supports the pelvic procedure itself, not a hip diagnosis. Pairing a bony pelvis anesthesia code with a hip fracture or hip osteoarthritis code is a mismatch that payers catch quickly.

ICD-10-CM draws the same pelvis-versus-hip line that CPT does. The sacrum fracture category, S32.1, carries an Excludes2 note for fracture of hip NOS (S72.0-). That means the two conditions are coded separately even when a patient has both. That is not a coincidence. It confirms that pelvis and hip are treated as distinct anatomical sites on both sides of the claim.

Modifiers and documentation every 01120 claim needs

Getting the code right is step one. Step two is everything a payer expects to see on the claim itself. CPT 01120 needs a physical status modifier and a provider role modifier on every line, with no exceptions.

Physical status modifiers, P1 through P6

Additional modifying units for P3 through P5 get added to the total unit count before multiplying by the conversion factor. Confirm per-payer modifying unit allowances, since commercial payers do not all follow ASA’s published values.

Medical direction and CRNA modifiers

Whether a Certified Registered Nurse Anesthetist (CRNA) can bill 01120 independently depends on state opt-out status under 42 CFR 482.52. States that have opted out of the federal physician supervision requirement let CRNAs bill on their own, using modifier QZ.

In non-opt-out states, the CRNA bills QX under physician supervision, and the supervising anesthesiologist bills QK or QY on a separate line. Confirm your state’s status before you submit, since it changes who bills what.

When one anesthesiologist medically directs two to four concurrent CRNA cases, both providers submit a claim. The anesthesiologist bills 50% of the allowable using QK, and the CRNA bills the other 50% using QX. Together they equal 100% of the allowable, not 200%. Getting that split wrong is a frequent audit trigger, on 01120 claims and everywhere else.

Qualifying circumstances add-on codes

Add-on codes may be reported alongside CPT 01120 when clinical conditions meet documented criteria. None of these apply automatically. Each requires medical necessity documentation in the anesthesia record.

• 99100 – Anesthesia for patient of extreme age (under 1 year or over 70 years). Adds 1 base unit. Requires documented age-related risk in the record.
• 99116 – Utilization of controlled hypotension. Applies when deliberate hypotension is induced to reduce surgical blood loss.
• 99135 – Utilization of controlled hypothermia. Applies when core body temperature is deliberately lowered.
• 99140 – Anesthesia complicated by emergency conditions. Applies when delay would significantly increase the threat to life. Requires documentation of the emergency condition.

What the anesthesia record has to show

CMS requires specific documentation elements to support every anesthesia claim. Missing a single required element can trigger an automatic denial or a post-payment audit. Maintain HIPAA-compliant clinical records that include all the following before submitting a CPT 01120 claim.

• Anesthesia start and stop times – Exact times, not estimated. Start time is when the provider begins patient preparation; stop time is when they are no longer in attendance.
• Physical status assignment – P1 through P6 documented in the anesthesia record, matching the modifier reported on the claim.
• Pre-operative evaluation – A documented pre-anesthesia assessment covering relevant medical history, medications, allergies, and airway assessment.
• Intraoperative anesthesia record – Continuous monitoring data (vital signs, medications, fluids, gases) recorded at regular intervals throughout the procedure.
• Post-anesthesia care – Documentation of patient status at transfer out of the operating room and any recovery room observations.
• Qualifying circumstances documentation – If add-on codes (99100, 99116, 99135, or 99140) are billed, the specific clinical circumstance must be explicitly documented.

Common mistakes that turn a clean pelvis claim into a denial

Most 01120 denials trace back to a short, repeatable list. Here is what to check before a claim goes out.

• Coding it as a hip procedure – Attaching 01120 to a hip arthroplasty or hip fracture repair. Use the 01200-01214 hip family instead, and match the base units to the code actually billed.
• Missing physical status modifier – Submit P1 through P5 on every claim line. A claim without one fails automated edits before a human ever reviews it.
• Clock time instead of anesthesia time – Anesthesia time starts at patient preparation, not surgical incision. Using OR clock time misstates the time units.
• Wrong ICD-10 linkage – Pairing 01120 with a hip osteoarthritis or hip fracture diagnosis. The diagnosis needs to reflect a pelvic bone condition instead.
• Confusing 01120 with 01173 – Billing 01120 for an open repair of a pelvic ring disruption or acetabular fracture, which belongs under 01173 at 12 base units.
• Unsupported qualifying circumstances – Billing 99100 without documented age-related risk. Stating the patient’s age alone is not enough; the record needs to show the risk itself.

Before you submit, run this checklist:

• Confirm the operative report describes the bony pelvis, not the hip joint or femur.
• Match the base units, 6, to CPT 01120 specifically, not a neighboring pelvis or hip code.
• Verify the physical status modifier and provider role modifier are both on the claim.
• Check that the ICD-10 code reflects a pelvic bone diagnosis supporting medical necessity.
• Pull the current year’s conversion factor for the payer and locality before estimating reimbursement.

How Pabau keeps pelvis and hip billing from blurring together

Anesthesia billing runs on volume, and volume is exactly where a six-unit bony pelvis code and an eight-unit hip arthroplasty code start to blur together. Practice management software like Pabau builds claims management tools around the procedure code actually documented in the anesthesia record. Base units, time, and modifiers stay tied to what happened in the operating room, not to an assumption made from the surgical schedule.

Digital anesthesia forms, part of Pabau’s patient intake tools, capture start and stop times, physical status, and qualifying circumstances at the point of care. That data flows straight into the billing record. It is one less manual transcription step, and one less place for a bony pelvis case to get miscoded as a hip case.

Tired of pelvis and hip codes getting mixed up?

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Getting bony pelvis anesthesia billing right

CPT code 01120 is simple once the boundary is clear. Six base units, a bony pelvis diagnosis, and modifiers that match the provider’s role are what separate a clean claim from a denial. The mistake to avoid is the one this code invites: treating pelvis and hip as interchangeable. CPT and ICD-10 both treat them as two different anatomical worlds.

Pabau’s claims management tools help catch a mismatched code before it reaches a payer. That might be a pelvis claim wearing hip base units, or a modifier that never made it onto the line. If cleaner anesthesia billing is the goal, book a demo to see the workflow in practice.

Continue your research

Billing for a total hip arthroplasty instead? See our guide to CPT code 01214 for the correct hip joint anesthesia code and base units.

Need a structured billing workflow for surgical procedures? Claims management software from Pabau helps practices reduce denials and track modifier assignments across provider types.

Managing multi-location surgical or anesthesia practices? Multi-location management tools centralize billing workflows across sites, including per-location conversion factor tracking.

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