Opens in a new tab

Sinusoid sign

The sinusoid sign in lung ultrasound refers to the dynamic, undulating appearance of the pleural line, often seen during inspiration and expiration in healthy lungs. This subtle, wave-like motion reflects the normal sliding of the visceral and parietal pleura, indicating the absence of pneumothorax or significant pleural adhesions. Recognizing the sinusoid sign is a key diagnostic feature for ruling out conditions that impede lung sliding.

This ultrasound finding is critical for medical professionals evaluating lung pathology, particularly in emergency and critical care settings. It helps differentiate normal lung mechanics from abnormalities, making it an essential component of pulmonary ultrasound assessment and aiding in accurate and timely diagnoses.

Clinical Author

Dr. Emma Khabure is an experienced Family Physician in Kenya with a dedicated focus on point-of-care ultrasound (POCUS) across clinical settings. Over the past 3 years, Dr. Emma Khabure has...

Read More
Want to learn more?

POCUS Essentials Course

Learn More

Related Posts by Term

POCUS QA process

The QA Gap: Why Most POCUS Programs Still Don’t Have One and How to Fix It

POCUS training can give clinicians the confidence to scan. But
continue reading

How AI Will Change the Way You Practice POCUS — Insights From Our Expert Panel

Part 1 of a 3-Part Series on Artificial Intelligence in
continue reading

Building the Next Generation of Ultrasound Educators: The GUSI MedConnect Instructor Training Program

In a small practice room at Touro University California, a
continue reading

MedConnect – Bruno Vargas

“I don’t know how to be a doctor without using
continue reading

Closing the Maternal Care Gap in Rural Philippines With POCUS

Bridging the Maternal Care Gap with POCUS In many rural
continue reading

How Lung Ultrasound Helps Clinicians Catch Tuberculosis Sooner

Webinar Summary: June 18, 2025 | Presented by Global Ultrasound
continue reading

The FASH Exam: POCUS for HIV-Associated Tuberculosis

The FASH exam is a focused POCUS protocol that helps
continue reading

Hands-On POCUS Training for Primary Care in San Francisco

See how GUSI teaches hands-on POCUS for primary care in
continue reading

POCUS vs. CT Scan: When Ultrasound Is the Safer First Step

POCUS provides immediate, radiation-free answers to focused clinical questions, while
continue reading

Contribute to the POCUSpedia

Help us improve the accuracy and completeness of the POCUSpedia. Your contributions help maintain the highest standards of factual content.
Contributors who provide verified corrections or additions will be credited with a link to their chosen web address. We appreciate your expertise and time in helping us maintain accurate information about POCUS

As a [Specialty] clinician, POCUS has completely changed how I practice. GUSI’s training gave me the confidence to make faster, more accurate decisions for my patients.

JONATHAN DOE
Private Practice Owner

Suggest a Correction

* Required fields

“”