Billing and Documentation for Fetal Nonstress Tests (NSTs)

Coding Tip: Billing and Documentation for Fetal Nonstress Tests (NSTs)

The Society for Maternal-Fetal Medicine (SMFM) Coding Committee; Trisha Malisch, CCS-P, CPC, COBGC; Robert Rossi, MD; Barbra Fisher, MD, PhD

Introduction

Fetal nonstress tests (NSTs) are one of the most frequently used tools for antepartum fetal surveillance in high-risk pregnancies. Accurate documentation is critical to:

• Demonstrate medical necessity
• Support CPT® code selection (e.g., 59025 when an NST is performed alone)
• Distinguish a discrete NST from continuous inpatient fetal monitoring, which is not reported with 59025
• Reduce denials, particularly when NSTs are billed in addition to global maternity care or other surveillance tests

This Coding Tip focuses on what must be documented for an NST and how that documentation supports appropriate billing.

When Is It Appropriate to Bill an NST?

In general, CPT 59025 may be reported when all of the following are met (always confirm with individual payer policies and current CPT guidance):

1. Clinical Indication Exists
• NST is performed when “medically necessary” for a recognized high-risk condition or concern (e.g., hypertensive disorders, diabetes, fetal growth restriction, oligohydramnios, decreased fetal movement, post-term pregnancy, monochorionic twins).
2. Physician/Qualified Health Professional Involvement
• A physician or other qualified health care professional supervises and/or interprets the NST and generates a written report or signed note. When only the professional component is billed (e.g., hospital outpatient setting), modifier -26 is appropriate.
3. Not Continuous Inpatient Monitoring
• Continuous fetal heart rate and uterine contraction monitoring in labor or during observation is generally included in the E/M or observation service and is not reported with 59025.

Billing Pearls and Common Pitfalls

1. NST Alone vs. NST with Biophysical Profile
• 59025: NST performed alone.
• 76818: Biophysical profile with NST.
• 76819: Biophysical profile without NST.
• 76815 + 59025: “Modified BPP” (limited ultrasound for AFI + NST) when both components are performed and documented.
2. Global Obstetric Care Bundling
• Some payers (including certain commercial and managed care plans) consider routine NSTs included in global obstetric or antepartum care codes and do not separately reimburse them; others allow separate payment for medically necessary NSTs in high-risk pregnancies.
• Always check payer contracts and policies to determine whether 59025 may be billed separately and what diagnoses justify medical necessity.
3. Inpatient Continuous Monitoring
• Continuous fetal monitoring on Labor & Delivery (e.g., for induction, augmentation, or active labor) is not reported with 59025 or 59020; it is included in the inpatient E/M or consultation service.
4. Multiple NSTs on the Same Day (Same Fetus)
• CPT Assistant–based and payer policies typically instruct: bill 59025 for the initial NST; subsequent NSTs on the same day for the same fetus are reported with 59025 and modifier 76 (repeat by same physician) or 77 (repeat by different physician), when allowed.
5. Multiple Gestations
• Many payers allow separate reimbursement per fetus (e.g., twin pregnancies) when medically necessary tests are performed and documented for each fetus. Policy language often requires either units of service (e.g., 2 units of 59025) or separate line items with an appropriate modifier (e.g., 59 or 51), linked to diagnoses indicating multiple gestation.

6. Place of Service and Components
• In hospital outpatient or freestanding testing centers, the technical component (-TC) is usually billed by the facility, and the clinician bills only the professional component (-26) for interpretation.
• Ensure the report is clearly attributed to the interpreting provider to support the professional fee.

Key Documentation Elements for an NST

Who decides what must be in an NST report?

The AMA/CPT® code descriptor (59025) defines the service you’re billing, but it doesn’t dictate line-by-line documentation content.

CMS and other payers require that your medical record supports the code and medical necessity and follow any payer coverage policies.

The clinical content of the report—baseline FHR, variability, accelerations, decelerations, uterine activity, duration, interpretation, and plan—comes from specialty practice parameters and standards of care (ACOG/SMFM).^1,2 Those standards are what auditors and payers typically rely on to decide whether your documentation shows that a true NST was performed.

SMFM has recommended that the NST report include the following:

• Patient Name

• Date of Service

• Gestational Age

• Indication for Test

• Fetal heart rate baseline

• Results, (i.e. reactive, non-reactive)

• Physician Signature

Conclusion

Clear, standardized documentation of NSTs:

• Demonstrates that a complete, time-limited fetal surveillance test was performed
• Supports appropriate use of CPT 59025 and related codes
• Reduces denials related to bundling, repeat testing, or insufficient documentation

Members are encouraged to review payer-specific policies and ACOG/SMFM/AIUM guidance on antenatal fetal surveillance indications and documentation.

Download the PDF

Members should submit any coding questions to the SMFM Coding Committee “Ask a Coding Question” website (https://www.smfm.org/ask-a-coding-or-PM-question). Additional information and resources are also available on our coding website (smfm.org/coding).

References

1. Antepartum fetal surveillance. ACOG Practice Bulletin No. 229. American College of Obstetricians and Gynecologists. Obstet Gynecol 2021;137:e116–27.