Thoracentesis is a procedure to remove fluid or air from the pleural space (the area between the lungs and chest wall) using a needle or catheter. Correct coding of thoracentesis is vital for accurate billing and compliance. This article reviews the official 2025 CPT codes for thoracentesis, explains the differences between codes (such as diagnostic vs. therapeutic uses and use of imaging guidance), and guides ultrasound documentation, modifier application, Medicare NCCI bundling rules, commercial payer variations, documentation requirements, and common denial reasons.

All information is based on the latest 2025 CPT and billing guidelines, with references to authoritative sources including CMS, the AMA, NUCC, and AAPC.

CPT Codes for Thoracentesis

The Current Procedural Terminology (CPT) codes for thoracentesis are maintained by the American Medical Association (AMA) [1]. Notably, there were no changes to the thoracentesis codes in the 2025 CPT code set (no new, deleted, or revised respiratory system codes) [7]. The primary thoracentesis-related CPT codes and their descriptors are:

32554 – Thoracentesis, needle or catheter, aspiration of the pleural space; without imaging guidance [1].
32555 – Thoracentesis, needle or catheter, aspiration of the pleural space; with imaging guidance [1].
32556 – Pleural drainage, percutaneous, with insertion of indwelling catheter; without imaging guidance [1].
32557 – Pleural drainage, percutaneous, with insertion of indwelling catheter; with imaging guidance [1].

Codes 32554 and 32555 describe a standard thoracentesis (aspiration of pleural fluid/air) where the needle or small catheter is removed at the end of the procedure [4]. In contrast, codes 32556 and 32557 describe placement of an indwelling pleural catheter (e.g. chest tube or pigtail catheter) that is left in place for continuous drainage [4]. The choice between these codes depends on whether the catheter was removed after aspiration (thoracentesis) or left in the pleural space (for ongoing drainage).

Diagnostic vs. Therapeutic Thoracentesis

Thoracentesis can be performed for diagnostic purposes (removing fluid for analysis) and/or therapeutic purposes (removing fluid/air to relieve symptoms). Importantly, the CPT code is the same regardless of the intent – there are no separate codes for “diagnostic thoracentesis” versus “therapeutic thoracentesis.” As the AAPC explains, if a provider uses a needle or catheter to remove pleural fluid (whether to obtain a sample or to relieve an effusion), you would report CPT 32554 (or 32555 if imaging is used) [4]. In practice, a single thoracentesis often serves both purposes (fluid may be sent to the lab for analysis, and the removal of fluid provides symptom relief), and it should be coded only once per side.

Because the same code covers both diagnostic and therapeutic aspirations, documentation should clearly state the clinical purpose and outcome. For example: “Removed 800 mL of cloudy fluid from left pleural space for symptomatic relief; sample sent to pathology for cytology.” This indicates both therapeutic effect and diagnostic evaluation, justifying the procedure. There is no additional CPT code if the fluid is sent for lab analysis – it’s part of the thoracentesis service.

Pleural biopsy considerations: Medicare’s National Correct Coding Initiative (NCCI) bundles pleural biopsy (32400) with thoracentesis unless it’s a distinct procedure [2]. Therefore, only if a separate biopsy is documented should 32400 be billed, and it must be appended with modifier -59 or a Medicare XU modifier to indicate a distinct procedure. If no separate tissue sample was taken, do not report 32400 in addition to the thoracentesis [4].

Imaging Guidance and Ultrasound Documentation

Imaging guidance is a key factor in thoracentesis coding. CPT 32555 and 32557 explicitly include imaging guidance, whereas 32554/32556 do not [1]. In practice, the most common guidance modality is real-time ultrasound, although CT or fluoroscopy might be used in some cases. When coding:

If imaging guidance (e.g. ultrasound) is used during the procedure: Choose the code that includes imaging guidance (32555 for a one-time aspiration, or 32557 if an indwelling catheter is placed). Do not bill a separate ultrasound guidance code (such as 76942) or other imaging code, because the guidance is considered an integral component of 32555/32557 [2]. CPT guidelines bundle the imaging into these procedure codes.
If no imaging guidance is used: Report 32554 (or 32556 if placing an indwelling catheter). These codes represent “blind” or anatomically guided thoracentesis without real-time imaging.

Ultrasound guidance documentation requirements: When imaging guidance is utilized (as in CPT 32555/32557), proper documentation is crucial. Medicare and industry standards require that if ultrasound guidance is billed, there must be permanently recorded images and a description of the findings or technique in the record [2].

The provider should document that ultrasound was used to identify the pleural fluid pocket and guide needle placement, and ideally note that ultrasound images were saved. A brief report of the guidance can be included in the procedure note (for example: “Ultrasound was used to localize a large left pleural effusion; under real-time ultrasound guidance, the needle was advanced into the fluid collection…”). Ensuring the note explicitly mentions the use of ultrasound (or CT, etc.) will support the use of the “with imaging guidance” CPT code and withstand payer scrutiny.

Proper Use of Modifiers (26, TC, 59, etc.)

Coding modifiers are critical to ensure accurate billing for thoracentesis and related services. Key modifiers and their use cases include:

Modifier 26 (Professional Component) – Do not use -26 on the thoracentesis procedure codes 32554-32557 themselves, because these are global surgical procedure codes, not split into professional/technical components like standalone imaging codes are.
Modifier 59 (Distinct Procedural Service) – Modifier 59 is crucial for overriding NCCI edits when you perform separate services that are not normally reported together. In thoracentesis coding, use 59 if you need to indicate that two procedures on the same day were independent of each other (e.g., a distinct pleural biopsy or a repeat thoracentesis at a separate session) [2]. Medicare now encourages the use of more specific X-modifiers (XE, XP, XS, XU) in place of 59 in many cases.
Modifier 50 (Bilateral Procedure) – Thoracentesis codes are defined as unilateral procedures (one pleural space). If a thoracentesis is performed on both the left and right pleural spaces during the same session, you should indicate a bilateral service. Medicare prefers the use of modifier -50 on a single line with one unit to denote a bilateral procedure (they will typically pay 150% of the single code rate). Commercial payers may require separate lines with LT and RT modifiers.
Modifier 25 (Significant Separate E/M Service) – If an Evaluation & Management (E/M) service is performed on the same day as the thoracentesis, modifier -25 may be needed on the E/M code. Generally, the pre-procedure evaluation work is considered part of the procedure itself. However, if the physician performed a significant, separately identifiable E/M service (e.g., evaluating multiple conditions), then the E/M can be billed with modifier 25 [6].

Medicare Billing Guidelines and NCCI Edits

The National Correct Coding Initiative (NCCI) policy manual and edits are particularly important to follow for Medicare claims. Key Medicare guidelines include:

Post-procedure chest X-ray is bundled: After a thoracentesis, it is common practice to obtain a chest radiograph (e.g. CPT 71045) to confirm lung re-expansion. According to the NCCI Policy Manual, this immediate post-procedure chest X-ray is considered part of the thoracentesis package and should not be billed separately [2][8]. CMS explicitly states that a chest radiologic examination performed to confirm the success of the procedure or absence of complications is integral to the procedure.
Imaging guidance is bundled: If one were to erroneously code a guidance ultrasound (76942) in addition to 32555, Medicare’s edits would flag and deny the imaging code as bundled [2].
Medically Unlikely Edits (MUEs): Medicare’s MUE for thoracentesis codes is typically 2 units per day for 32554/32555 (one per pleural space).
Physician supervision: Thoracentesis, when performed in a hospital outpatient setting, is considered a therapeutic service that typically requires at least direct physician supervision by Medicare rules.

Commercial Payer Coverage and Differences

While many commercial insurance payers align with Medicare’s coding guidelines, there can be variations in coverage and billing rules for thoracentesis:

Bundling and edits: Most private payers implement coding edits similar to NCCI, meaning they also will not pay separately for things like post-procedure chest X-rays or unbundled imaging guidance.
Prior authorization: Unlike Medicare, many commercial insurers require prior authorization for outpatient hospital procedures or even office procedures like thoracentesis.
Bilateral procedure billing: Some commercial payers want two line items (32554 LT and 32554 RT) instead of a single 32554-50 line. Always refer to the payer’s billing manual.

Documentation Requirements to Support Billing

High-quality documentation is the foundation for correct coding. Key documentation points include:

Indication: Document the reason (e.g. “Large left pleural effusion causing shortness of breath”).
Technique details: Describe the site, needle size, and specifically whether imaging guidance was used.
Imaging results (if applicable): If ultrasound guidance was used (CPT 32555), document it thoroughly (e.g. “Ultrasound guidance was used to identify a pocket of fluid; images were saved to PACS”) [2].
Volume and character: Record the amount of fluid removed (e.g. “1200 mL of straw-colored fluid”).
Separate procedures: If any other procedure was done at the same session, document it clearly to justify any distinct service modifiers.

Common Reasons for Denials and How to Avoid Them

Denial: “Procedure not documented” – Occurs when 32555 is billed but the op note doesn’t mention ultrasound use. Fix: Ensure the note explicitly states imaging was used and saved.
Denial: “Bundled service” – Occurs if you bill 71045 (chest X-ray) or 76942 (ultrasound) on the same day. Fix: Follow NCCI bundling rules; do not bill routine post-procedure imaging [8].
Denial: “Missing modifier” – Occurs if an E/M is billed without modifier 25, or bilateral procedures are billed without modifier 50/RT/LT. Fix: Double-check modifier usage.
Denial: “Medical necessity” – Occurs if the diagnosis code is non-specific (e.g., “cough”) instead of the condition (e.g., J90 Pleural Effusion). Fix: Use specific ICD-10 codes.

References and Resources

For further reading and official guidance, you may consult:

[1] American Medical Association (AMA) CPT® Resources – The official source for CPT codes and guidelines.
[2] CMS National Correct Coding Initiative Policy Manual, Chapter 5 (2025) – Medicare coding rules for respiratory procedures, including bundling of imaging.
[3] Medicare Physician Fee Schedule Look-up – For global period, RVUs, and bilateral indicators.
[4] AAPC – Resources on thoracentesis coding and common pitfalls.
[5] NUCC (National Uniform Claim Committee) – 1500 Claim Form Reference Manual for modifier placement.
[6] CMS MLN Matters and Guides – General procedure coding and documentation guides.
[7] ACS Coding for Chest Procedures – Summary of CPT 2025 changes for general surgery.
[8] AAPC Forum: Chest X-rays and Thoracentesis – Discussion on bundling issues and strategies.

CPT Coding for Thoracentesis (2025 Guidelines)