OB/GYN Denial Patterns
OB/GYN practices face unique denial challenges driven by the global obstetric package rules. The most costly denials involve unbundling errors where services included in the global package are billed separately, or conversely, where separately billable complications are incorrectly included in the global fee. These errors are bidirectional: some lose revenue by not billing for separately payable services, and others create compliance risk by billing for services included in the package.
Denial Reason 1: Global Package Unbundling (CARC 97)
CARC 97 (payment adjusted based on modifier) is the most common OB denial, triggered when a service that is included in the global obstetric package is billed separately. Routine antepartum visits, the standard postpartum visit, and routine intrapartum care are all included. Billing a separate E/M code for a routine prenatal visit when the global package has been or will be billed results in denial of the E/M charge.
The fix requires clear workflow rules: all routine antepartum visits are tracked on the antepartum log and billed through the global package. Only visits that address non-routine complications with separate diagnoses are billed individually. The billing team must review every E/M charge submitted during a patient pregnancy to verify it represents a separately billable complication, not routine care.
Denial Reason 2: Antepartum Visit Count Disputes (CARC 16)
When billing antepartum-only codes (59425, 59426), payers may request documentation of the exact number of antepartum visits to verify the code selection. If the practice bills 59426 (7+ visits) but can only document 5 visits, the claim is denied or adjusted to 59425 (4-6 visits). The antepartum visit log is the primary defense against this denial.
Denial Reason 3: Preventive vs. Problem Visit Coding (CARC 50, CARC 11)
Well-woman exam denials mirror primary care preventive visit issues. Billing a preventive code for a visit that was primarily problem-focused, or billing a problem-focused E/M for a visit that was primarily preventive, triggers diagnosis-procedure mismatch denials. When both services are provided, both codes should be billed with modifier 25 on the E/M and separate diagnosis codes for each component.
Denial Reason 4: Ultrasound Coverage Limits (CARC 119)
Some payers include a specific number of obstetric ultrasounds in the global OB package or limit the number of covered ultrasounds per pregnancy. A practice that performs 4 OB ultrasounds when the payer covers 2 will see denials on the additional studies unless they are medically indicated by a complication diagnosis. Documentation of the clinical reason for each ultrasound beyond the standard protocol is essential.
Denial Reason 5: Missing Modifier on Split Visits (CARC 4)
When a well-woman exam and a problem visit are billed together, missing modifier 25 on the E/M code results in denial of the E/M component. The payer will process the preventive visit and deny the E/M as bundled. This modifier error costs the practice the full E/M reimbursement ($92 to $132) on every affected visit.
Prevention Strategy
OB/GYN denial prevention requires: an antepartum visit tracking system, clear rules for identifying separately billable complications vs. routine care, modifier 25 prompts for split preventive/problem visits, and ultrasound documentation protocols that support each study beyond the standard pregnancy protocol. Practices that implement all four components maintain denial rates below 5%.