Most Common OB/GYN Billing Mistakes and How to Prevent Them

Did you know that, according to insurers, 19% in-network claims in 2023 were denied, which is nearly one in five bills for treatment already delivered? These claim denials in OB/GYN rarely happen due to major errors. It comes from small, routine slips and tiny gaps that quietly turn clean work into denials, underpayments, and refund requests.

In this blog, we have discussed common OB/GYN billing mistakes and how providers and their teams can prevent them. You will see simple checklists you can implement immediately. Read through to the end, and you will leave with a concise guide that stops revenue leakage before it starts.

Confusion about the Global Maternity Package

The mistake: Billing component codes when a global maternity package applies, or billing a global package when your group provided only part of the care. It causes denials, underpayments, or refunds if you pick the wrong path.

What to know:

Global maternity codes (e.g., 59400, 59510, 59610, 59618) include routine antepartum visits, the delivery, and routine postpartum care. They don’t include many ancillary services like ultrasounds, special screening tests, amniocentesis, and other separately reportable procedures. If another provider handled part of the care, bill the appropriate component codes instead of the global. Payer policies vary slightly, so always confirm the plan’s definition of “global.”

How to prevent global maternity package mistakes:

• Keep a one-page “what’s included / what’s excluded” sheet for each major payer (list common add-ons that aren’t bundled).
• If your practice provided only delivery or only antepartum/postpartum care, use delivery-only or component codes per the payer’s grid.
• Clearly document exception services (e.g., detailed ultrasounds, genetic screening) so they’re billed outside the bundle.

Misusing Modifier 25 on same-day E/M + procedures

The mistake: Forgetting modifier 25 when a significant, separately identifiable E/M occurs on the same day as a minor procedure (e.g., IUD insertion) or using it on nearly every visit. Underuse of modifier 25 causes missed revenue, and overuse without support can trigger audits.

What to know:

Use modifier 25 on the E/M service when and only when the patient’s condition required significant, separately identifiable work beyond the usual pre-/post-work of the procedure performed that day. Document the separate problem, medical decision-making, and why additional work was needed.

How to prevent modifier 25 mistakes:

• Train your team: Provide ongoing training for providers and billing staff on Modifier 25 criteria and evolving payer policies.
• Strengthen communication: Standardize handoffs between providers and billers, and encourage billers to request clarification on documentation when needed.
• Audit routinely: Perform periodic chart reviews to assess Modifier 25 usage and catch recurring issues before they lead to denials.
• Leverage technology: Use billing software that flags missing or mismatched modifiers in real time.

Using Modifier 59 (or X{EPSU}) to “bypass” bundling edits

The mistake: Appending -59 to force payment when two codes bundle under NCCI edits, even if the services aren’t truly distinct. This causes denials, refund demands, or audit risk.

What to know:

-59 indicates a distinct procedural service and should be used only when no more specific modifier applies. CMS encourages using the X-modifiers for clarity: XE (separate encounter), XS (separate structure), XP (separate practitioner), XU (unusual non-overlapping). Always review NCCI edits first and document why the services are distinct.

How to prevent modifier 59 mistakes:

• Turn on NCCI edits in your scrubber and require a note in the claim when using -59/X-mods stating the clinical reason (different site, separate encounter, etc.).

Obstetric ultrasound coding and documentation misfires

The mistake: Choosing the wrong ultrasound code (e.g., 76801 vs 76805 vs 76815 vs 76816) or missing required elements. Payers downcode, deny, or request refunds when documentation fails to match the CPT code’s scope.

What to know:

• 76805 (standard 2nd/3rd trimester) requires a defined anatomic survey.
• 76815 (limited) is a focused check (for a specific question) rather than a full survey.
• 76816 (follow-up) documents interval growth or re-exam of a known concern. Your report must include the elements required for the code you choose, guided by AIUM/ACR/ACOG/SMFM practice parameters. Many payers limit the number of 76805 per pregnancy and expect 76815/76816 for subsequent focused exams when medically necessary.

How to prevent obstetric ultrasound coding and documentation:

• Build structured ultrasound templates that auto-prompt the required elements for 76805 and 76816.
• Train staff to select limited vs follow-up vs standard based on the clinical question and gestational age.

Pap smear mix-ups (Q0091/G0101, screening vs. diagnostic)

The mistake: Billing Q0091 (collection of screening Pap for Medicare) when the visit was diagnostic, missing frequency rules, or forgetting special modifier rules for repeat unsatisfactory screens.

What to know:

For Medicare screening, use G0101 for the screening pelvic exam and Q0091 for the collection of a screening Pap (not for diagnostic Pap). Most beneficiaries qualify every 24 months; high-risk or certain younger patients after an abnormal Pap may qualify annually. If a screening specimen is unsatisfactory, CMS instructs using Q0091 with modifier -76 for the repeat collection.

How to prevent pap smear mix-ups:

• Intake should flag screening vs problem-oriented visits; select screening HCPCS only when appropriate.
• Load Medicare screening intervals and the Q0091 + -76 repeat rule into your EHR order sets.

LARC (IUD/implant) coding gaps, missing device codes, or wrong combinations

The mistake: Billing insertion/removal without the device HCPCS, omitting an E/M + -25 when a truly separate evaluation occurred, or mis-coding same-day removal and reinsertion.

What to know:

Most LARC visits require three lines when appropriate: the procedure (e.g., 58300 for IUD insertion or 58301 for removal), the device (HCPCS J-code such as J7300 for copper IUD; J7296–J7298/J7301 for levonorgestrel IUDs), and a separately identifiable E/M + -25 when the evaluation goes beyond the usual pre/post work. When removal and insertion occur the same day, follow payer rules on multiple-procedure or distinct-service modifiers and document the reason (e.g., expired, side effects). Link appropriate Z30 diagnoses for contraceptive management.

How to prevent LARC coding gaps:

• Create LARC “smart sets” that preselect procedure + device and prompt for Z30 diagnosis codes; add an E/M with -25 only when supported.

Medicaid sterilization (tubal) claims without a valid HHS-687 consent

The mistake: Attempting payment for postpartum tubal ligation or interval sterilization without a valid HHS-687 consent not signed far enough in advance, exceeding the 180-day window, missing signatures/dates, or using an outdated form version.

What to know:

Federal rules require that consent be signed ≥30 and ≤180 days before the sterilization procedure (with limited exceptions like premature delivery or emergency abdominal surgery where ≥72 hours must elapse). Many state programs and MCOs require attaching a completed HHS-687 to the professional and facility claims; denials are non-appealable if the consent window or signatures aren’t valid. Forms are periodically updated, so confirm you’re using the current version.

How to prevent it:

• Track consent signature date, expected delivery date, and form version in your pre-op checklist; build alerts for the 180-day expiration.
• Train OR schedulers and billers to verify the form is complete and attached to all related claims (surgeon, anesthesia, facility).

CLIA and QW pitfalls for office tests (e.g., urine pregnancy)

The mistake: Performing or billing waived tests without an active CLIA certificate, or using modifier QW incorrectly.

What to know:

Your site must have an appropriate CLIA certificate for every test performed. Many waived tests require modifier QW on claims; CMS regularly publishes updates adding new waived tests and reminding practices to align billing with their CLIA status. Urine pregnancy testing (81025) is a classic point-of-care example; confirm local MAC requirements for QW usage.

How to prevent CLIA and QW pitfalls:

• Store your CLIA number in the practice management system; audit it on every claim line that needs it.
• Keep a quick reference of current CLIA-waived tests and QW rules for your MAC.

Timely filing misses and prior authorization missteps

The mistake: Submitting outside the filing window or scheduling procedures requiring PA without documented approval.

What to know:

For Medicare, claims must be received within 12 months (1 calendar year) of the date of service; late claims aren’t payable except for narrow exceptions. Commercial and Medicaid managed care plans vary, so you need a payer-specific grid. Separately, new federal rules are tightening prior authorization expectations (faster decisions, reasons for denials, and public reporting) for Medicare Advantage, Medicaid/CHIP plans, and certain marketplace plans. Operational changes are rolling out as payers implement the Interoperability and Prior Authorization Final Rule (CMS-0057-F).

How to prevent filing mistakes:

• Maintain a live, timely filing matrix and set claim-submission alerts at 30/60/90 days post-DOS.
• For surgeries and advanced imaging (e.g., LEEP, hysteroscopy, sterilization), a PA number is required before scheduling and attaching it to the encounter.
• Watch payer updates on the new federal PA standards so your workflows (and APIs, where available) keep pace.

Administrative claim data errors (NPI, place of service, taxonomy)

The mistake: Submitting claims with mismatched billing vs. rendering NPI, using the wrong place of service (POS) code, or keeping outdated taxonomy and enrollment info.

What to know:

• POS codes indicate where the service occurred and affect payment (e.g., office vs. outpatient hospital). Use CMS’s POS code set and your MAC’s guidance.
  
• NPI data (billing and rendering) must be current and match payer enrollments. Keep your NPPES record up to date, including the correct primary taxonomy. Misalignment between your claim and what the payer has on file commonly triggers rejections.

How to prevent administrative claim data errors:

• Run a monthly audit of billing NPI + rendering NPI + taxonomy across payers; verify against NPPES and payer portals.
• Train front-office and coders on when to use POS 11 (office) vs POS 22 (outpatient hospital) and other common OB/GYN sites.

Diagnosis coding mistakes in obstetrics

The mistake: Using Z34 (supervision of normal pregnancy) when complications exist, or forgetting the trimester-specific detail.

What to know:

For routine, uncomplicated prenatal care, use Z34 series codes. For high-risk or complicated pregnancies, report O-codes with trimester specificity; Chapter 15 codes generally take sequencing priority when an obstetric complication is present. Always code to the highest specificity required by ICD-10-CM.

How to prevent diagnosis coding mistakes:

• Add an intake question about complications. If yes, use O-codes and include the trimester; reserve Z34 for true routine encounters.

Conclusion

Accurate billing in an OB/GYN practice is essential. It protects compliance and keeps the practice financially steady. The aim is not perfection. The aim is a dependable system that produces clean, defensible claims.

Insurers have different rules, so provide simple, payer-specific guidance. Keep training staff on a regular schedule. Use global maternity codes correctly. Apply the right modifiers. Record what was done, especially ultrasounds and procedures, with complete notes. These actions reduce denials and prevent underpayments.

Technology strengthens the process to avoid medical billing mistakes in OB/GYN. Claim-scrubbing tools catch errors before submission. Timely filing alerts prevent missed deadlines. Routine internal audits confirm that standards are met and stay met.

Address common OB/GYN billing mistakes before they recur. Tighten internal controls where gaps appear. The result is steadier revenue and smoother operations. Reliable, error-free OB/GYN billing supports fair reimbursement and helps sustain the practice’s integrity.