S M Wazien Wafa S Saadun Tarek Wafa, Mohammad Zikri Ahmad, Mohd Boniami Yazid, Mohd Hashairi Fauzi, Shaik Farid Abdull Wahab, Nafisah Idris

AIM

To demonstrate the advantage of bedside ultrasound to exclude potentially life-threatening chest pathology over other imaging modality.

METHODS

A 56-year-old moderately built lady with history of pulmonary tuberculosis contact was diagnosed with sepsis secondary to right foot diabetic foot ulcer.

She was planned for emergency debridement. She was otherwise stable hemodynamically with no signs of respiratory distress. Pre-operation chest x-ray showed incidental finding of suspicious opaque line over left lung which was preliminary reported to be left pneumothorax.

Bedside ultrasonography however showed that sliding sign were present on all areas, with presence of seashore sign and lung pulse. No lung point detected.

The patient was then sent for plain chest computed tomography (CT) which confirmed no pneumothorax. With this finding, the opaque line which mimicked pneumothorax in the chest x-ray was reported to be skinfold artefact of the patient.

RESULTS

Skinfold shadow is a common artefact on chest x-ray, especially in anterior-posterior (AP) position. It is more frequent to occur in older patients or those with weight loss.  It can mimic the visceral pleural line and can be wrongly interpreted as pneumothorax.

In this case, patient is asymptomatic, and the finding of opaque density on chest x-ray is an incidental one.

The ultrasound performed had safely exclude the presence of pneumothorax, and based on a meta-analysis review, the usage of ultrasound to detect pneumothorax has higher negative predictive value compared to chest radiography.

Ultrasound thus could provide real-time bedside confirmation of presence or absence of a pneumothorax, without the need to expose patient to higher radiation from CT thorax or repeated chest radiography.

CONCLUSION

Skinfold artefact can be mistakenly interpreted as pneumothorax on chest radiography and this potentially life-threatening pathology can be safely excluded with bedside lung ultrasonography.

The higher sensitivity of ultrasound compared to chest x-ray and its immediate availability compared to CT thorax could avoid delay in the definitive management of patient.

Although CT scan is considered ‘gold standard’ imaging modality in detecting pneumothorax, it requires more resources and could further expose patient to the risk of unnecessary radiation.