Speaker's Highlight

• Don Sin University of British Columbia, St. Paul Hospital (Canada)
  Kenneth R. Chapman Toronto General Hospital Research Institute (Canada)
• Parameswaran Nair McMaster University (Canada)
  Carolyn Calfee UCSF (U.S.A.)
• Gregory P. Downey University of Colorado School of Medicine (U.S.A.)
  David A. Schwartz University of Colorado School of Medicine (U.S.A.)
• Neil Schluger Tuberculosis Control Branch, California Department of Public Health (U.S.A.)
  Nick Kim Critical Care & Sleep Medicine, University of California San Diego (U.S.A.)
• Nicola Hananiah Baylor College of Medicine (U.S.A.)
  Jae-Joon Yim Seoul National University College of Medicine (Republic of Korea)
• Koichiro Asano Tokai University School of Medicine (Japan)
  Diahn-Warng Perng Taipei Veterans General Hospital (Taiwan)
• Konstantinos Kostikas University of Ioannina (Greece)
  Karin Klooster University Medical Center Groningen (Kingdom of the Netherlands)

• Lung Ultrasound in the Diagnosis of Pleural Effusion

  Lung ultrasound has become a valuable bedside tool for identifying pleural effusion, estimating its size and guiding immediate management. In respiratory medicine, its strength lies in real-time imaging: clinicians can examine the pleural space while assessing breathing effort, oxygenation and haemodynamic stability.

  Pleural fluid may develop with heart failure, pneumonia, malignancy, pulmonary embolism, trauma or systemic disease. Symptoms are often non-specific, ranging from breathlessness and pleuritic pain to cough and fatigue. A focused ultrasound examination can quickly determine whether fluid is present and whether it appears simple, complex or loculated.

  For Australian clinicians, this matters in busy emergency departments, respiratory wards and intensive care units where access to formal imaging can vary. A patient in a Melbourne tertiary hospital, a regional service in Queensland or a remote clinic supported by retrieval teams may need an early answer before computed tomography or specialist review is available.

  Lung ultrasound does not replace clinical assessment, chest radiography or CT when those tests are indicated. It adds a portable, radiation-free view that can shorten diagnostic uncertainty, support safer procedures and help clinicians monitor change over time.

  Why Bedside Ultrasound Matters

  Pleural effusion appears on ultrasound as an anechoic or hypoechoic space between the parietal and visceral pleura. In a supine patient, fluid may collect posteriorly and be difficult to detect with a limited anterior examination. Scanning the posterolateral chest, especially above the diaphragm, improves sensitivity.

  The method is particularly useful when a chest X-ray is equivocal or when a patient cannot be transported safely. It can be repeated after diuresis, antibiotics or drainage without exposing the patient to ionising radiation. In Australian public hospitals, where imaging demand can be high, this ability to perform a focused assessment at the bedside is clinically practical.

  Feature	Lung Ultrasound	Chest X-ray	CT Chest
  Radiation	None	Low dose	Higher dose
  Bedside use	Excellent	Limited	Usually requires transport
  Small effusions	Often detected	May be missed	Detected reliably
  Septations and fluid character	Well assessed	Poorly assessed	Assessed in detail
  Procedure guidance	Real-time	No	Limited for bedside use
  Main limitation	Operator dependence	Lower sensitivity	Cost, radiation and access

  Recognising Fluid And Its Character

  A simple effusion is usually dark, homogeneous and free-flowing. With respiration, the collapsed lung may move within the fluid, producing the “sinusoid sign” on M-mode. The diaphragm should be identified carefully because subdiaphragmatic fluid, ascites or an enlarged organ can mimic a pleural collection.

  Complex effusions may contain internal echoes, debris, fibrin strands or septations. Echogenic fluid can suggest blood, pus or highly cellular material, although ultrasound appearance alone cannot establish the cause. A cloudy collection in a patient with fever and pneumonia raises concern for parapneumonic effusion or empyema.

  The spine sign can help identify fluid above the diaphragm in a supine patient, as vertebral echoes become visible through the fluid-filled space. Dynamic assessment is important: movement of the lung, diaphragm and septations can distinguish a genuine pleural collection from adjacent pathology.

  Linking Findings With The Clinical Picture

  Ultrasound findings should be interpreted alongside symptoms, examination and laboratory results. Bilateral effusions with diffuse B-lines and reduced cardiac function may support congestion from heart failure. A unilateral collection with fever, pleural pain and focal consolidation points towards infection, while an unexplained recurrent effusion may require investigation for malignancy.

  Pleural thickening, nodularity and irregular diaphragmatic surfaces are concerning features, although they are not diagnostic in isolation. Research into pulmonary fibrosis mechanisms also highlights why chronic inflammatory and fibrotic lung disorders require broader clinical context rather than reliance on a single image.

  When a patient has recent trauma, an ultrasound scan may identify haemothorax rapidly. In a patient with suspected pulmonary embolism, a pleural effusion is usually a secondary and non-specific finding; it should not be treated as proof of embolic disease. The scan contributes to a larger diagnostic pathway.

  Safe Scanning In Australian Practice

  A low-frequency curvilinear probe is generally suitable for deeper pleural fluid, while a high-frequency linear probe can show superficial pleural detail. The patient should be positioned as comfortably as possible, often sitting upright or leaning forward. If the patient is critically unwell, scanning in the supine or semi-recumbent position may be necessary.

  Australian practice includes major metropolitan services in Sydney, Melbourne and Brisbane, as well as smaller hospitals where one clinician may cover emergency, inpatient and procedural duties. Clear documentation of the probe position, patient posture, fluid depth and internal appearance helps maintain continuity when images are reviewed remotely or by a visiting respiratory physician.

  In rural Western Australia, the Northern Territory and remote Queensland, transfer decisions may depend on retrieval availability and weather. Point-of-care ultrasound can support early stabilisation and referral discussions, but it should never delay drainage or transfer when the patient has sepsis, respiratory compromise or suspected tension physiology.

  Avoiding Common Diagnostic Traps

  A small amount of fluid can be physiological, while a larger collection may still produce few symptoms. Scanning only the anterior chest can miss dependent fluid. Mistaking the liver or spleen for pleural pathology is another avoidable error, particularly when the diaphragm is not clearly visualised.

  Consolidated lung may resemble tissue within an effusion. Air bronchograms, the position of the diaphragm and the movement of the abnormal area during respiration can help distinguish consolidation from a fluid collection. Loculated fluid may sit outside the usual dependent position and can be missed if the examination is too brief.

  Ultrasound also has limited ability to define the full extent of pleural disease, mediastinal pathology or a mass deep within the chest. Findings that are atypical, progressive or clinically discordant should prompt formal imaging and specialist assessment rather than repeated bedside scanning alone.

  Practical Scanning Recommendations

  A consistent examination improves reliability, particularly for clinicians developing point-of-care ultrasound skills. In Australian training environments, supervised scanning, image archiving and local credentialling processes help ensure that a useful bedside test is applied safely across emergency and respiratory settings.

  The following habits make pleural assessment more dependable:

  • Scan both sides for comparison, including posterior and posterolateral zones where feasible.
  • Identify the diaphragm before measuring or describing a collection.
  • Use respiratory movement and M-mode when the diagnosis is uncertain.
  • Record whether fluid is free-flowing, echogenic, septated or loculated.
  • Mark the safest drainage site only after assessing depth, nearby organs and the patient’s position.

  Putting Findings Into Practice

  When pleural fluid is suspected, ultrasound can answer several immediate questions: Is fluid present? Is it large enough to matter clinically? Does it appear simple or complex? Is there a safe pathway for aspiration or drainage? These answers guide the next step without pretending that imaging alone reveals the complete diagnosis.

  For thoracentesis, real-time or pre-procedure ultrasound reduces the chance of puncturing the diaphragm or an abdominal organ. The operator should reassess immediately before needle insertion because fluid can shift with posture and respiration. Appropriate sterile technique, consent, anticoagulation review and post-procedure monitoring remain essential.

  The practical takeaway is straightforward: use lung ultrasound early, scan systematically, interpret the pleural space alongside the patient’s whole clinical picture, and escalate to chest radiography, CT or specialist review when the findings do not fit.

  Richard Russell Nuffield Department of Clinical Medicine, University of Oxford (United Kingdom)
• Mona Bafadhel King’s College London (United Kingdom)
  David Jackson Guy’s and St Thomas’ Hospital, King’s College London (United Kingdom)
• James Chalmers University of Dundee (United Kingdom)
  David Price University of Aberdeen (United Kingdom)