CPT code 58146 – Abdominal myomectomy (complex)

Key takeaways

CPT code 58146 covers open abdominal myomectomy for 5 or more intramural myomas, or intramural myomas weighing over 250 g in total.

Surface myomas never count toward 58146, so a case with only subserosal or pedunculated fibroids stays on 58140.

Payers expect the intramural count and total weight in the operative note, with the pathology weight as corroboration.

A 90-day global period bundles routine post-op care, so follow-up visits inside that window aren’t billed separately.

Pabau, the practice management platform we build, pre-fills claims from the patient record and validates required claim fields before sending through Claim.MD.

What CPT code 58146 covers, and when it applies

CPT code 58146 is the open abdominal myomectomy code for heavier or more numerous fibroids. The AMA descriptor reads as follows.

Myomectomy, excision of fibroid tumor(s) of uterus, 5 or more intramural myomas and/or intramural myomas with total weight greater than 250 g, abdominal approach.

Either condition is enough on its own. Five small intramural myomas qualify, and so does a single intramural myoma weighing 300 g. The surgeon removes them through a laparotomy, repairs the uterine wall and leaves the uterus in place.

That uterine preservation separates 58146 from the hysterectomy codes. Surface myomas don’t count toward either threshold, and the next two sections show why that matters.

What happens in the OR decides the code

Open abdominal myomectomy starts with a laparotomy, either a Pfannenstiel or a vertical midline incision, depending on uterine size and fibroid location. The surgeon incises the serosa and myometrium over each myoma and enucleates it from its pseudocapsule.

The myometrial defects are then closed in layers to rebuild the uterine wall. The removed myomas are weighed before they go to pathology. That weight, together with the count, is what the coder reads to choose the code.

• Approach: Open abdominal (laparotomy). Laparoscopic cases use 58545 or 58546 instead.
• Myomas that count: Intramural myomas only. Their number and total weight drive the choice between 58146 and 58140.
• Surface myomas: Subserosal and pedunculated myomas can come out in the same session, but they don’t count toward 58146.
• Uterine preservation: Yes. The uterus is reconstructed after the myomas are removed.

Why 58140 steals your 58146 claim

Code 58140 covers 1 to 4 intramural myomas with total weight of 250 g or less and/or removal of surface myomas. CPT code 58146 takes over once the case passes either intramural threshold.

The weight in both descriptors is the total weight of the intramural myomas. It isn’t the uterine weight or the weight of every specimen in the jar. Surface myomas fall under 58140 whatever their number or size, so leave them out of the count. The chart below shows the order to read the note in.

A common error looks like this. The op note says multiple fibroids were removed and gives no weight, so the coder falls back to 58140. Pathology later reports 310 g of intramural myoma tissue.

Payers expect the count and weight in the operative note, and the pathology weight corroborates it. Ask the surgeon for an addendum before the claim goes out.

Neighboring codes that look like 58146

Once the count and weight are settled, check the approach and whether the uterus stayed. If the surgeon ends up removing the uterus, the case moves to a hysterectomy code such as 58150 instead.

ICD-10 pairings that prove medical necessity

The procedure code says what the surgeon did, and the diagnosis has to explain why. For CPT code 58146, that means a uterine leiomyoma code, usually backed by a symptom code.

Symptom codes for heavy bleeding, pelvic pain or urinary pressure strengthen medical necessity. Payers also look for evidence that conservative management was tried or clinically contraindicated. These pairings are examples, not a payer-approved list, so check each payer’s policy.

What the op note has to say for 58146

Medical necessity gets the claim considered. The operative note gets it paid. Because 58146 pays more than 58140, auditors check its two definitional facts first.

Strong medical billing documentation for this procedure puts each element below in the operative note. Payers expect them there, and the pathology report corroborates the weight.

• Intramural myoma count: The exact number removed. “Multiple fibroids” can’t support the 5-or-more criterion.
• Total intramural weight: Grams, recorded before the specimen goes to pathology. “Specimen sent to pathology” says nothing about weight.
• Surface myomas, listed separately: So the coder can leave them out of the count.
• Surgical approach: A plain statement that the approach was open abdominal.
• Location and closure: Where each myoma sat and how the myometrium was closed in layers.
• Blood loss and operative time: Both support modifier 22 when the case was substantially harder than usual.

Modifiers for 58146: Use them sparingly

Most 58146 claims need no modifier. When one applies, it changes how the code is paid or how it sits next to other codes from the same session.

Modifier 22 doesn’t guarantee extra payment. Payers decide whether to increase it, and many want a written request with clinical justification. Reserve it for cases that clearly exceed the usual work of CPT code 58146.

How Medicare prices CPT 58146

Every modifier decision feeds into the same fee schedule math. Medicare rates change each year with the Physician Fee Schedule final rule, so this guide doesn’t quote dollar amounts. Use the CMS Physician Fee Schedule lookup and the FastRVU 2026 lookup to pull current values for your locality.

The relative value unit (RVU) structure follows the standard three-component model used across the AMA CPT code set.

The formula is (work RVU × work GPCI) + (PE RVU × PE GPCI) + (MP RVU × MP GPCI), multiplied by the conversion factor. GPCI stands for geographic practice cost index. High-cost metro areas carry higher GPCIs, so the same surgery pays more there.

The 90-day global: What you can still bill

Once the claim is paid, the global period governs what follows. CPT code 58146 carries a 90-day global surgical period set by CMS. The surgeon’s fee covers related post-op care for those 90 days, so routine follow-up visits aren’t billed separately.

• Modifier 24: Unrelated evaluation and management service during the global period. The diagnosis code must clearly reflect a condition unrelated to the original surgery.
• Modifier 79: Unrelated procedure or service performed by the same physician during the global period.
• Modifier 78: Return to the operating room for a related procedure during the global period, such as managing a post-operative complication.
• Modifier 58: Staged or related procedure during the global period that was planned at the time of the original procedure.

Pre-operative E/M visits on the day before or the day of surgery are bundled too. The exception is the visit where the decision for surgery was made, which takes modifier 57 on the E/M code.

Prior auth for CPT 58146: Get it before the scalpel

All of that assumes the case was approved first. Many commercial payers and Medicare Advantage plans require prior authorization for CPT code 58146. Traditional Medicare doesn’t generally require it, though a Medicare Administrative Contractor may set coverage criteria in a Local Coverage Determination.

• Commercial insurance: Prior authorization is commonly required. Attach pre-operative imaging (MRI or ultrasound), symptom documentation, and evidence that conservative management failed.
• Medicare Advantage: Plans set their own prior auth rules, separate from traditional Medicare. Verify with each plan before scheduling.
• Medicaid: State programs vary. Some require prior auth, and others leave it to managed care organizations with their own criteria.
• Auth under the wrong code: Say the auth was approved for 58140, but the surgeon removed seven intramural myomas. Ask the payer whether the authorization can be updated before you submit.
• Retroactive authorization: Emergency procedures may qualify, but elective myomectomy usually doesn’t. For most payers, a missed prior auth can’t be fixed after the service.

Place of service: Where 58146 gets billed

The place of service (POS) code tells the payer where the surgery happened and sets the facility or non-facility rate. CPT code 58146 is an inpatient-oriented procedure, almost always performed in a hospital.

58146 is rarely performed in an ambulatory surgical center (ASC). Verify payer and ASC-list coverage before scheduling one there.

The facility bills its own share under the hospital outpatient or ASC payment system. The physician bills on a CMS-1500 at the fee schedule rate. A wrong POS code pays the wrong rate, which means either a recoupment or a corrected claim.

A well-prepared superbill captures the POS at the time of service. Pabau submits CMS-1500 and 837P claims through Claim.MD, with CPT and ICD-10 code libraries and required-field checks.

One claim, from the OR to the clearinghouse

Here’s how a clean 58146 claim moves, using an example case. The surgeon removes seven intramural myomas and one pedunculated myoma through a Pfannenstiel incision. The intramural myomas weigh 410 g together.

1. Op note: The surgeon dictates the intramural count (seven), the total intramural weight (410 g) and the pedunculated myoma as a separate line.
2. Code selection: The case crosses both thresholds, so the coder reports 58146 with D25.1 first and symptom codes after it.
3. Authorization check: The auth on file was requested for 58140 before surgery. The billing team asks the payer to update it to 58146.
4. Claim build: POS 21 goes on the claim because the patient was admitted. No modifier applies, since the case was routine for its size.
5. Submission: The claim goes out as an 837P through the clearinghouse, which returns an acceptance or a rejection to fix.
6. Payment and follow-up: The remittance posts payment, and post-op visits over the next 90 days are logged without charges.

That closes one loop of revenue cycle management for the case. The checklist below turns those steps into a pre-submission routine.

Before you submit: A 58146 checklist

Run this list on every 58146 claim before it leaves the practice. Each line maps to a denial reason in the next section.

• Intramural count and total intramural weight are stated in the operative note.
• Surface myomas are listed separately and left out of the count.
• The open abdominal approach is stated in plain words.
• Prior authorization is on file for 58146, not 58140.
• The POS code matches where the surgery happened.
• Modifier 22, if used, has a cover letter quantifying the extra work.
• No routine post-op visits inside the 90-day global are billed separately.
• A D25 diagnosis comes first, with symptom codes after it.

Why 58146 claims get denied, and the fix

Many 58146 denials trace back to a short list of preventable documentation problems. The checklist above catches them before the claim reaches the payer.

Reading denial codes for this code family helps you spot the patterns behind repeat denials. A structured denial management workflow then turns those patterns into fixes.

When the same denial keeps coming back, change the process as well as the claim. A US claims clearinghouse with eligibility checks and claim edits stops many POS, authorization and diagnosis errors before payer review.

How claims management software keeps 58146 claims moving

In many practices, a coder reads the op note, re-keys codes into a payer portal and finds a missing authorization number only after a rejection. Each round trip delays payment.

Pabau’s claims management software builds the claim from the patient record instead. The CPT code attached to the service lands on the charge line, and ICD-10 codes come from the recorded problem list.

Built-in CPT and ICD-10 lookup libraries help coders confirm each code. The Send button stays locked until required fields, such as authorization numbers, are complete. Claims then go out through Claim.MD, with eligibility checks and remittance posting.

Choosing between 58140 and 58146 stays a coding decision based on the op note. Pabau clears the re-keying and missing-field rejections, so your team spends its time on that decision.

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Pabau pre-fills claims from the patient record and validates required claim fields before sending through Claim.MD. Your team spends less time re-keying 58146 claims and fixing rejections.

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Conclusion

CPT code 58146 is won or lost in the surgeon’s dictation. When the note gives the intramural count and the total intramural weight, the coder has a choice that’s easy to defend. When it doesn’t, the claim drifts to 58140 or into an appeal.

So start upstream. Add required count and weight fields to your myomectomy op-note template, and match the prior auth to the procedure performed. Keep modifier 22 for cases you can defend on paper. A few extra lines per note cost far less than reworking a denied surgical claim.

Book a demo to see how Pabau pre-fills your gynecology surgery claims and holds them until every required field is complete.

Continue your research

Need to verify related claims before submission? Understanding clean claim requirements covers what payers check before processing surgical procedure claims.

Removing submucous fibroids through the scope instead? CPT code 58561 covers hysteroscopic removal of leiomyomata and how it is billed.

Want to understand clearinghouse validation for surgical codes? How 837 electronic claim files work explains the structure payers use to validate CPT and ICD-10 pairs on submission.

Building a denial reduction process for your gynecology practice? Medical billing compliance guidance outlines the documentation and audit standards that apply to surgical codes.

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