Winter 2025 Issue

Taming the Obstetrics Coding Beast
By Elizabeth S. Goar
For The Record
Vol. 37 No. 1 P. 14

From Pregnancy to Postpartum

Having babies is big business in the United States, with nearly 3.6 million births recorded in 2023 at an average cost of $18,865 per birth.1 Prenatal care typically involves 10 to 15 visits to the obstetrician’s office for a range of tests including routine blood work, a glucose test, genetic testing, ultrasounds, and other screenings. Delivery, which takes place in hospitals more than 98% of the time, is typically followed by a 48- to 96-hour hospital stay, depending upon the type (vaginal or cesarean), any complications, and any need for specialty care or monitoring.2,3

With so many moving parts, it’s understandably complex to secure full and appropriate reimbursement for the plethora of services provided prenatal to postbirth. However, the level of complexity is exacerbated by several factors that are unique to coding obstetrics (OB).

“The first is the global obstetrical package, which bundles all routine obstetrical care into one CPT code,” says Trisha Malisch, CCS-P, CPC, COBGC, lead coder on the Society for Maternal-Fetal Medicine Coding Committee. “The other is that ICD-10 coding for OB can be complex [and] the challenges are about the same whether the site of service is inpatient or outpatient.”

Nigel Spier, MD, medical director of OB/GYN for ModMed, also points to the global OB package as a major complicating factor for both documentation and coding. Not only are “you accounting for the antepartum care [but] there are all kinds of different rules around that … because each antepartum or office visit itself is not a billable event, but [rather] a trackable event.”

Often, coders will utilize “dummy” F and H codes, depending on the payer, to track these events until they can be “tallied up to determine [if] you meet the minimum required for the full global OB package by that payer,” he says, adding that the one-size-fits-all EHR systems designed primarily for evaluation and management coding for individual and short episodes of care add to the challenge—particularly when it comes to managing payers’ information requests and claim denials.

“What obstetricians need is a way to track the number of visits and make sure they’re capturing all the information that justifies the ultimate outcome, which is the delivery,” he says. “You would think that would be pretty straightforward, but it’s not. I remember my office manager arguing with payers; the baby was in. The baby came out. Pay the doctor.”

An Inherently Complex System
The global OB package only scratches the surface when it comes to factors contributing to the complexity of OB coding. One goes all the way back to health care’s 2015 transition to ICD-10-CM. According to Leigh Poland, RHIA, CSS, vice president of coding services with AGS Health, not only does ICD-10 require a more granular representation of clinical concepts, but it also increased the number of OB-related codes by about 44,000 over ICD-9.

Further, OB diagnosis and coding has its own set of chapter-specific coding guidelines and “there are many unique definitions related to OB coding, so you must pay close attention to the ICD-10-CM coding tabular instructional notes and definitions to make sure you are selecting the appropriate codes,” she adds.

Indeed, the coding challenges start with the pregnancy confirmation visit. While logic dictates that the confirmation visit would be the first entry into the OB global package, that is not the case with all payers. “Unless you have a system that understands all the types of scenarios, you might get a denial for that confirmation of pregnancy visit,” Spier says.

OB coding is fraught with other opportunities for coding-related delays and denials due to a necessary level of complexity that mirrors that of the pregnancy journey. Poland, along with Angels Rani Jeritta, CCS, AGS Health’s manager of coding services and coding education, took a deep dive into the challenges of pregnancy-related coding in the webinar, “Masterclass on Obstetrics Coding: From Pregnancy to Postpartum.”4

It starts simply enough: OB codes are found in chapter 15 of ICD-10-CM in the range O00-O9A, Pregnancy, Childbirth, and the Puerperium (postpartum) and take precedence over codes from other chapters. For example, for a normal inpatient delivery, O80 is always the principal diagnosis. For routine outpatient prenatal visits with no complications present, the principal diagnosis code comes from category Z34 (encounter for supervision of normal pregnancy).

Here, however, is where we get our first taste of the complexity that lies ahead; even though OB codes are found in chapter 15 of ICD-10, the Z codes used for some principal diagnoses should not be used with codes from that chapter. And things get harder from there:

• Supervision of high-risk pregnancy. The first-listed diagnosis code for routine visits should come from category O09 (supervision of high-risk pregnancy), although secondary chapter 15 codes may also be used. For labor or delivery without complications, O80 (encounter for full-term uncomplicated delivery) is used. When complications occur, the applicable chapter 15 code is used.

• Episodes when no delivery occurs. When no delivery takes place, the principal diagnosis should correspond to the principal pregnancy complication that necessitated the encounter. If multiple complications are treated or monitored, any of the codes can be listed first.

• Episodes when delivery occurs. The complication that prompted the admission is the principal diagnosis. For multiple conditions, the first-listed code should be the one that relates most closely to the delivery and the others are listed as additional diagnoses.

• Admission with other delivery. When delivery is not normal, the principal diagnosis is the reason for admission. For example, if a patient is admitted for treatment of preeclampsia and has a C-section complicated by fetal deceleration, the principal diagnosis is preeclampsia.

• Admission for other obstetrics care. When the admission or encounter is for care other than delivery, the reason for admission or encounter is the principal diagnosis code. For example, an office visit for care of a 40-year-old patient in the fourth month of her third pregnancy (O09.522, Z3A.00) or admission of a patient who delivered a healthy newborn in the taxi on the way to the hospital (Z39.0). If more than one complication is present, any one of them can be the first-listed diagnosis.

Additional codes from other chapters may also be used in conjunction with chapter 15 codes to further specify conditions. If the patient with pregnancy is admitted with a condition and the physician states the condition is incidental to pregnancy, code ICD-10-CM code Z33.1 would be assigned.

Documentation is also critical when assigning the trimester code from category Z3A, as documenting gestation at 39 weeks and six days makes the correct code 39 weeks. However, for inpatient admissions covering multiple weeks, gestation is based on the date of admission, not discharge.

ICD-10-PCS procedure codes and guidelines also come into play for delivery assistance procedures, including induction of labor, artificial rupture of membranes, fetal head rotation, forceps delivery, vacuum extraction, episiotomy, and cesarean delivery. Further, contraceptive management and procreative management are covered by a series of Z codes that can be supplemented by additional codes if an underlying condition is present. Finally, special codes are needed when a pregnancy extends beyond the usual 39-week gestation period: O48.0 for postterm pregnancy lasting 40 completed weeks through any number of days into week 42, and O48.1 for prolonged pregnancy for 43 or more weeks.

Complications add yet another layer of complexity. Those involving fetal conditions that affect management of pregnancy, which are indicated with codes from categories O35 (maternal care for known or suspected fetal abnormality and damage) and O36 (maternal care for other fetal problems), are only reported if they are responsible for modifying the management of the mother (ie, requires diagnostic studies, additional observation, special care, or pregnancy termination). Similarly, fetal stress complications (O68–O77) are only reported when management of the mother is impacted.

“The coding challenge for each pregnancy stage is really understanding what services are being provided, and when,” Malisch says. “It can be tricky when there isn’t a code for a procedure or diagnosis. An example of this is single umbilical artery—there isn’t a specific code for this condition, so we have to use a general code that doesn’t really describe the problem.”

The Documentation Impact
While the examples above are not exhaustive, they effectively illustrate the multifaceted and complex nature of OB coding, and why it is a prime target for denials. In fact, the OB denial rate exceeds 22%, putting it at the top of the list among specialties. The impact of inaccurate codes and claim denials can be significant.

“From a physician practice standpoint, inaccuracy can delay payment or result in incorrect payment and sometimes can cause confusion for the patient when they get their explanation of benefits or their statement,” Malisch says. “Inaccuracy or inefficiency can also contribute to incomplete and/or unreliable data.”

Poland adds that undercoding can lead to underpayments, while overcoding can lead to financial penalties. However, the impact goes beyond financial; it can create barriers to improving the quality of maternity services.

“Pregnancy and OB coded data is being used to measure, evaluate, and improve the quality of maternity services,” she says, noting that the Joint Commission Perinatal Care Measure Set, the CMS Inpatient Quality Reporting Program, state Medicaid agencies, statewide quality improvement collaboratives, and the Merit-based Incentive Payment System all track OB and pregnancy data for quality improvement efforts.

As is often the case, improvements in both coding accuracy and denial rates can be achieved through improvement efforts. Malisch points out that most coders already utilize computer-assisted coding solutions and software “that allows them to look up codes and modifiers, check for coding edits, and look at RVUs [relative value units], and these tools are really essential.”

“Of course,” she adds, “electronic medical records also have a lot more capability now to guide physician code selection or suggest codes that can then be analyzed by a professional coder.”

In addition to utilizing computer-assisted coding and computer-assisted professional coding tools, Poland notes that “a medical coder can improve their coding skills and accuracy by staying up to date on coding guidelines, continuous learning and regularly attending workshops and training sessions, utilizing coding software effectively, performing thorough reviews of patient documentation, conducting self-audits, and seeking feedback from peers or supervisors.”

At the end of the day, however, “Clinical documentation is always key to accurate coding, because it supports both the services that were rendered and why those services were clinically appropriate,” Malisch says. “In practices that have professional coders, documentation is often the first communication point between the physician and their coder, so timeliness and accuracy of documentation contributes a lot to efficiency.”

In “Master Class on Obstetrics Coding,” AGS Health’s Poland highlights several areas that are ripe for both queries and clinical documentation improvement. Anemia is at the top of the list.

“This is one of those areas … where we see facilities putting policies together on what is appropriate blood loss [and] hemoglobin and hematocrit levels after delivery. If it falls below those appropriate levels, then they like for us to initiate a query,” she says, reminding coders to also be alert to other indicators such as palpitations, syncope, dizziness, lightheadedness, pale, fatigue, lethargy, or weakness. “All of these are warning signs that there might be that need to place a query for anemia if it’s not documented,” Poland says.

Other areas that often trigger queries related to postpartum hemorrhage and chorioamnionitis (aka amnionitis or intraamniotic infection), a bacterial infection of the membranes surrounding the fetus that occurs before or during labor. Poland adds, “You want to make sure you’re looking at pathology results very closely because there are opportunities there for queries.”

The AI Influence
Documenting and coding the OB journey is one that most expect to benefit from the rise of increasingly powerful artificial intelligence (AI) tools. The question is, how much?

Poland says that AI is most often being deployed in areas with high volumes of data and repetitive codes, including emergency medical settings and outpatient medical imaging. “Due to the complexities of OB and pregnancy coding, it would be a challenge to utilize an AI tool for obstetrics coding,” she says, adding that she has not seen any AI products that are targeting the area.

Malisch says it’s likely that some aspects of clinical documentation already benefit from AI. However, she concurs that the specialty is not well-suited for extensive automation. While it may be possible to automate some OB coding, “it’s not likely the easiest specialty area for coding automation. This is particularly true in the subspecialty of maternal-fetal medicine, where pregnancy is high-risk or complicated.”

She suggests that tracking routine antepartum visits that are included in the global package is one area where automation might be helpful, as it could help ensure complete capture of all billable services.

Spier is more optimistic, noting that AI can play a significant role in improving first-pass claim rates by documenting care in real-time through ambient listening and leveraging advanced algorithms to analyze it, along with the patient’s history, to identify information that is both important for care decisions and to support claims.

For example, AI can identify when a patient has dealt with high blood pressure at the end of previous pregnancies, indicating a higher risk of gestational hypertension during her current pregnancy—one of the most common contributors to maternal morbidity and mortality. Monitoring the patient requires more office visits than usual, which normally would trigger a payer inquiry without proper documentation.

With AI, “Now you have all that information right there when you present it to the payer, so there’s a much better chance for a first-pass success when you submit that claim and much less chance for denial,” Spier says. “That’s the ideal situation for OB/GYNs … to know that once my patient delivers, all the documentation went out too, so you’ll get paid appropriately. And if it’s high risk, you’ll get paid for that too, as you should.”

— Elizabeth S. Goar is a freelance health care writer in Benton, Wisconsin.

 

References
1. Martin JA, Hamilton BE, Osterman MJK. Births in the United States, 2023. NCHS Data Brief. 2024;507:10.15620/cdc/158789.

2. Pendergrass M. How much does it cost to have a baby? 2025 averages. Forbes Advisor website. https://www.forbes.com/advisor/health-insurance/how-much-does-it-cost-to-have-a-baby/#:~:text=Average%20Cost%20of%20Childbirth%20in,(KFF)%20Health%20System
%20Tracker. Updated January 2, 2025.

3. Maternal and newborn care in the United States. In: National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Division of Behavioral and Social Sciences and Education; Board on Children, Youth, and Families; Committee on Assessing Health Outcomes by Birth Settings; Backes EP, Scrimshaw SC, eds. Birth Settings in America: Outcomes, Quality, Access, and Choice. Washington, D.C.: National Academies Press; 2020. https://www.ncbi.nlm.nih.gov/books/NBK555484/#:~:text=Hospitals%20are%20
the%20most%20common,a%20Level%204%20maternity%20unit 

4. Poland L, Jeritta AR. Master class on obstetrics coding: from pregnancy to postpartum [webinar]. AGS Health website. https://www.agshealth.com/webinars/master-class-on-obstetrics-coding-from-pregnancy-to-postpartum/. Published 2024.

 

Resources for OB Coders
To help coders keep their obstetric coding skills in peak form, our experts shared several resource recommendations.

In addition to the “Master Class on Obstetrics Coding” webinar, AGS Health’s Leigh Poland, RHIA, CSS, suggests keeping up to date with official coding resources like AMA and ICD-10-CM/PCS Coding Guidelines, AMA CPT Assistant, and AHA Coding Clinic for HCPCS and ICD-10-CM/PCS.

“I also find the ICD-10-CM and ICD-10-PCS Coding Handbook and The Merck Manual very helpful,” she adds.

Trisha Malisch, CCS-P, CPC, COBGC, suggests AAPC and the American College of Obstetricians and Gynecologists, as well as the Society for Maternal-Fetal Medicine, which offers a discounted membership option for coders. “We have a lot of resources, including a service that allows members to ask coding questions that are answered by the coding committee. I would also suggest making sure AHIMA and CMS are in the bookmarks bar,” she adds.

— ESG