CPT code 01160: Anesthesia for closed pelvic joint procedures

Key Takeaways

CPT code 01160 describes anesthesia for closed procedures involving the symphysis pubis or sacroiliac joint, sitting within the Anesthesia for Procedures on the Pelvis (Except Hip) section of the CPT code set.

The code carries 4 base units per the ASA Relative Value Guide; reimbursement is calculated as (base units + time units + qualifying circumstance units) multiplied by an anesthesia conversion factor that varies by payer and locality.

Modifiers AA, QX, QY, QZ, and QK are the most commonly applied modifiers; selecting the wrong medical direction modifier is a leading cause of claim denials for 01160.

Pabau’s claims management software helps surgical and anesthesia practices track modifier rules, attach supporting documentation, and reduce denials at submission.

Pelvic anesthesia claims are among the most modifier-sensitive in the CPT code set. A single wrong modifier on CPT code 01160 can trigger an automatic denial, and incomplete anesthesia time documentation compounds the problem. Most billing errors on this code trace back to the same two gaps: misapplied medical direction modifiers and missing operative start/stop timestamps.

This reference covers the complete billing picture for CPT code 01160: its official description, base unit assignment, time unit calculation, applicable modifiers, paired ICD-10 diagnosis codes, reimbursement methodology, and the documentation requirements that keep claims clean.

CPT code 01160: description and clinical context

CPT code 01160 is defined by the American Medical Association (AMA) as: Anesthesia for closed procedures involving symphysis pubis or sacroiliac joint. It sits within the broader section “Anesthesia for Procedures on the Pelvis (Except Hip)” in the claims management software workflow most surgical practices follow when processing pelvic procedure cases.

Two anatomical landmarks define this code’s scope:

• Symphysis pubis: The cartilaginous joint connecting the two pubic bones at the front of the pelvis. Closed procedures here include manipulation under anesthesia, a fluoroscopically guided pubic symphysis injection, and closed reduction of pubic symphysis diastasis. When any of these is done under anesthesia, 01160 reports the anesthesia service, not the injection or reduction itself.
• Sacroiliac (SI) joint: The joint between the sacrum and the ilium. Closed procedures include SI joint injections, arthrodesis (where no open incision is made), and closed manipulation.

The critical word in the descriptor is closed. Once a surgeon makes an incision to directly access either joint, the procedure moves out of 01160 territory and into CPT 01170 (open procedures) or CPT 01173 (open repair of fracture disruption of pelvis). Billing 01160 for an open case is an upcoding risk with potential audit consequences.

Where 01160 fits in the anesthesia CPT hierarchy

Understanding the neighboring codes prevents misassignment. The pelvis (except hip) section runs sequentially, with each code mapped to a specific procedure type and anatomical scope:

Base unit values shown reflect the Arizona ICA fee schedule (2020-2021) and are provided for reference; confirm current values against the AMA’s annual CPT coding resources and your payer’s current contract before billing. The HIPAA compliance documentation requirements for anesthesia records apply equally across all codes in this section.

Base units, time units, and reimbursement calculation

Anesthesia reimbursement follows a formula that is distinct from every other section of the CPT code set. Unlike surgical codes paid on a flat RVU basis, anesthesia payment scales with the actual time the anesthesia provider spends with the patient.

The standard formula, recognized by CMS’s Physician Fee Schedule, is:

For a typical 45-minute closed SI joint injection under anesthesia, the claim totals 7 units before any qualifying circumstances. Exact dollar reimbursement depends on the payer’s contract and geographic locality. Use the FastRVU 2026 RVU lookup tool to verify current Medicare RVU values for your region.

Anesthesia time: start, stop, and documentation

Anesthesia time begins when the anesthesia provider starts preparing the patient for induction in the operating room (or equivalent area) and ends when the provider is no longer in personal attendance. Both timestamps must appear in the surgical practice management software record or paper anesthesia record. Missing or inconsistent timestamps are the most common reason payers request medical records after an anesthesia claim is submitted.

Most commercial payers and Medicare follow the 15-minute per unit convention. Some workers’ compensation carriers use 10-minute increments. Always check your payer contracts before calculating units.

Modifiers for 01160 anesthesia claims

Modifier selection determines whether a claim pays at the full rate or triggers a review. Four categories of modifiers apply to CPT code 01160: provider status, medical direction, physical status, and qualifying circumstances.

Provider status and medical direction modifiers

These modifiers tell the payer who performed the anesthesia and under what supervisory arrangement:

• AA: Anesthesia services performed personally by an anesthesiologist. Full payment applies. No concurrent cases.
• QK: Medical direction by a physician of two, three, or four concurrent anesthesia procedures. Payment is typically 50% of the AA rate per case.
• QX: CRNA service under the medical direction of a physician. Paired with QK on the physician’s claim.
• QY: Medical direction of one CRNA by a physician. Applies when the anesthesiologist directs a single CRNA.
• QZ: CRNA service without medical direction of a physician. Full CRNA payment; the supervising physician does not bill.
• AD: Supervision of more than four concurrent anesthesia procedures by a physician. Reimbursement capped at three base units per procedure.

Matching QK and QX on the respective physician and CRNA claims is mandatory. A claim with QX but no corresponding QK from the directing physician will generate a mismatch edit. Use digital intake and consent forms to pre-capture anesthesia provider assignments before the case date, reducing day-of documentation gaps.

Physical status modifiers

Physical status (P) modifiers add units to reflect patient health complexity. They are required by most payers for anesthesia claims:

• P1: Normal healthy patient (0 additional units)
• P2: Mild systemic disease (0 additional units for most payers)
• P3: Severe systemic disease (+1 unit under ASA guidelines)
• P4: Severe systemic disease that is a constant threat to life (+2 units)
• P5: Moribund patient unlikely to survive without surgery (+3 units)
• P6: Brain-dead patient for organ donation purposes (used in specific circumstances)

Not all payers reimburse for physical status units. Medicare, for example, does not pay additional units for P3-P5. Commercial payers vary. Check your payer contracts and use the AAPC Codify CPT lookup to confirm current payer-specific policies before reporting physical status units.

Qualifying circumstances add-on codes

Qualifying circumstances are billed as separate add-on codes alongside 01160, not as modifiers appended to it:

• 99100: Anesthesia for patient of extreme age (younger than 1 year and older than 70) (+1 unit)
• 99116: Utilization of total body hypothermia (+5 units)
• 99135: Controlled hypotension (+5 units)
• 99140: Emergency conditions (+2 units)

ICD-10 diagnosis codes commonly paired with 01160

CPT 01160 does not carry its own diagnosis requirements, but the surgical procedure it supports must be medically necessary. The paired ICD-10 code on the claim must justify both the underlying procedure and the use of anesthesia. Payers use automated edits to flag CPT-to-ICD-10 mismatches.

Common ICD-10 codes submitted alongside CPT 01160:

Verify ICD-10-CM pairings against the current fiscal year code set using the ResDAC coding resources page, which links directly to CMS update files. The automated billing workflows in Pabau flag mismatched CPT-to-ICD-10 pairs before a claim leaves the practice, catching errors that would otherwise generate a denial.

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Documentation requirements for clean 01160 claims

Clean anesthesia claims require documentation that goes beyond the anesthesia record itself. Payers auditing CPT 01160 claims typically look for five elements:

1. Pre-anesthesia evaluation: Completed within 48 hours before the procedure. Must include ASA physical status assignment, review of allergies, airway assessment, and anesthesia plan.
2. Intraoperative anesthesia record: Time-stamped start and stop of anesthesia, drugs and dosages administered, vital signs at regular intervals, and any intraoperative events.
3. Post-anesthesia note: Evaluation in the recovery area, confirming patient status meets discharge criteria. Required by CMS for Medicare claims.
4. Operative/procedure note: Confirms the procedure was closed (not open). A note describing an incision into the SI joint contradicts a 01160 claim and should prompt a code correction to 01170.
5. Medical necessity documentation: The referring or operating physician’s note establishing why the procedure was required. This is the primary support for the ICD-10 diagnosis code on the claim.

Storing these records in patient record documentation systems that link directly to the claim makes audit responses faster and reduces the administrative burden on billing staff. The medical forms and documentation workflows used during pre-anesthesia intake can be structured to capture all five required elements before the patient enters the OR.

CRNA vs. anesthesiologist: billing implications

The provider type changes both the modifier selection and the applicable payment percentage. When a CRNA performs the service under medical direction (modifier QX), Medicare pays 50% of the allowable to the CRNA and 50% to the directing physician (who bills QK). When the CRNA practices independently without medical direction (modifier QZ), the CRNA bills 100% of the allowable.

Opt-out states allow CRNAs to practice without physician direction. In those states, QZ is the standard modifier for independent CRNA anesthesia. In non-opt-out states, payers may require evidence of physician direction even when direction is claimed. The practice management platform your billing team uses should flag the state-specific rules for each claim before submission.

Related codes and when to use them instead of 01160

Code selection at the pelvis is error-prone because several procedures straddle the open/closed boundary or involve adjacent anatomical structures. Here is a practical decision framework for the most common crossover scenarios.

Use 01160 when: the procedure involves the symphysis pubis or SI joint and no incision is made. Examples: fluoroscopic SI joint injection, closed manipulation under anesthesia, closed reduction of SI joint dislocation.

Switch to 01170 when: the surgeon makes an incision to directly visualize or access the symphysis pubis or SI joint. Examples: open SI joint fusion, open reduction of pubic symphysis disruption, direct surgical stabilization of the SI joint.

Switch to 01173 when: the procedure involves open repair of a fracture or fracture-dislocation affecting the pelvis or acetabular column, including cases where the SI joint disruption is part of a pelvic ring fracture pattern. For sports medicine practice software users managing musculoskeletal injury cases, this code appears most often in polytrauma billing contexts.

Use 01120 when: the procedure involves the pelvis generally (not specifically the symphysis pubis or SI joint) and does not fall into the hip or femur code range. This is the catch-all pelvis code for procedures not specified by 01150, 01160, 01170, or 01173. Anesthesia providers billing for pelvic procedure billing codes in reproductive contexts should confirm whether 01120 or a more specific code applies.

Common 01160 billing errors and how to avoid them

The five errors below account for the majority of denials on CPT 01160 claims. Each is preventable with the right pre-submission workflow.

• Billing 01160 for an open procedure: The operative note describes an incision. The correct code is 01170 or 01173, depending on whether a fracture repair is involved. Outcome: upcoding exposure, potential recoupment.
• Mismatched QK/QX modifiers: The CRNA bills QX but the supervising anesthesiologist’s claim does not include QK (or vice versa). Outcome: automatic denial from payer crosscheck logic.
• Missing anesthesia start/stop time: Time units cannot be verified without timestamps. Outcome: payer downcodes to base units only, resulting in significant underpayment.
• Incorrect physical status modifier: P3 or P4 billed for Medicare without recognizing that Medicare does not reimburse physical status units. Outcome: claim processes but physical status units are stripped, creating a payment discrepancy.
• Outdated ICD-10 code: M54.5 (unspecified low back pain) retired as a standalone ICD-10-CM code in FY2021. Claims still using M54.5 may deny or require correction to the specific subcategory. Using HIPAA-compliant billing practices and integrated code-validation tools catches retired codes before submission.

A pre-submission checklist embedded in your compliance management tools can enforce these checks automatically, flagging each item before the claim reaches the clearinghouse.

Conclusion

CPT code 01160 is a low base-unit code with significant documentation complexity. The closed vs. open distinction, medical direction modifier matching, and anesthesia timestamp requirements each create denial risk when handled manually. Getting all three right on every claim requires systematic pre-submission checks, not memory.

Pabau’s claims management software helps anesthesia and surgical practices build those checks into the billing workflow, linking documentation requirements to each claim before submission. To see how it works for your practice, book a demo.

Continue your research

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