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Updated: May 19, 2026

Protocol and Guidelines for Point-of-Care Lung Ultrasound in Diagnosing Neonatal Pulmonary Diseases Based on International Expert Consensus
Published on: March 6, 2019
The V-line: a sonographic aid for the confirmation of pleural fluid
Paul Atkinson1, James Milne, Osama Loubani
1Dalhousie Medicine New Brunswick, 100 Tucker Park Road, Saint John, NB, E2L 4L5, Canada. Paul.Atkinson@dal.ca.
Background:
Ultrasound is being used increasingly to diagnose pathological free fluid accumulation at the bedside. In addition to the detection of peritoneal and pericardial fluid, point-of-care ultrasound allows rapid bedside diagnosis of pleural fluid.
Findings:
In this short report, we describe the sonographic observation of the vertebral or 'V-line' to help confirm the presence of pleural fluid in the supine patient. The V-line sign is a result of the fluid acting as an acoustic window to enable visualization of vertebral bodies and posterior thoracic wall, thus confirming the presence of pleural fluid.
Conclusions:
The V-line is a useful sonographic sign to aid the diagnosis of pleural free fluid.
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