76604

Ultrasound, chest (includes mediastinum), real time with image documentation

CPT code 76604 describes a diagnostic ultrasound examination of the chest, which encompasses the evaluation of the chest wall, the pleural space, and the mediastinum. This procedure utilizes high-frequency sound waves emitted from a transducer to produce real-time, dynamic images of internal structures. Unlike ionizing radiation used in X-rays or CT scans, ultrasound provides a safe and non-invasive method for evaluating soft tissues and fluid collections. Clinically, this code is most frequently used to detect and quantify pleural effusions, which are abnormal accumulations of fluid between the layers of the pleura. The ultrasound allows the clinician to determine if the fluid is free-flowing or loculated (trapped in pockets) and to characterize its nature, such as identifying the presence of septations or debris which might suggest an empyema or complex effusion. Beyond fluid assessment, 76604 is utilized to evaluate chest wall masses, identifying their depth, size, and relationship to the ribs or musculature. It can also be used to assess the movement of the diaphragm, which is essential in diagnosing diaphragmatic paralysis or dysfunction. The examination includes the mediastinum, though visualization there may be limited by air-filled lungs; however, it remains useful for evaluating enlarged lymph nodes or masses in specific acoustic windows. To report this code, the provider must perform a thorough real-time assessment and maintain permanent image documentation within the patient's medical record along with a formal written report.

Clinical Indications

  • Suspected pleural effusion based on physical exam or chest X-ray
  • Evaluation of chest wall masses, lumps, or localized swelling
  • Assessment of diaphragmatic movement and excursion
  • Characterization of pleuritic chest pain
  • Screening for pneumothorax in emergency or trauma settings
  • Evaluation of suspected mediastinal masses
  • Follow-up of abnormal findings on other imaging modalities
  • Assessment of suspected hemothorax or empyema

Procedure Steps

  1. Patient is positioned, typically in an upright sitting position for pleural evaluation or supine for chest wall/mediastinal assessment.
  2. A conductive ultrasound gel is applied to the chest area to facilitate sound wave transmission.
  3. The clinician selects an appropriate transducer, usually a high-frequency linear array for superficial chest wall structures or a lower-frequency curvilinear probe for deeper pleural visualization.
  4. The transducer is moved across the intercostal spaces to avoid rib shadowing and visualize the underlying pleura and lung surface.
  5. The pleural line is identified to observe 'lung sliding,' which confirms the absence of pneumothorax at that site.
  6. The presence, location, and volume of any pleural fluid collections are measured and characterized.
  7. Evaluation of the diaphragm is performed during both quiet and deep inspiration to check for paradoxical movement.
  8. Any identified masses in the chest wall or mediastinum are measured in at least two dimensions.
  9. Representative images are captured and archived in the imaging system for permanent documentation.
  10. A formal report is generated detailing the findings, including the presence or absence of fluid, masses, or dynamic abnormalities.

Coding Guidelines

  • 76604 requires both real-time imaging and permanent image documentation to be reported.
  • Do not report 76604 in conjunction with ultrasound guidance codes (e.g., 76942) unless the diagnostic ultrasound is a separate, distinct service performed prior to the procedure.
  • If the procedure is performed in a facility setting (e.g., hospital), the physician should append modifier 26 to denote the professional component.
  • This code should not be used for ultrasound of the heart; see echocardiography codes 93303-93308.
  • For ultrasound of the breast, refer to codes 76641 or 76642.
  • A written report signed by the interpreting physician is required for the professional component of the service.

Associated ICD-10 Codes