Sonographic appearances in transudative pleural effusions: not always an anechoic pattern.

Area of Science:

• Medical Imaging
• Pulmonology
• Diagnostic Ultrasound

Background:

• Sonographic classification of pleural effusion includes anechoic, complex nonseptated, complex septated, and homogeneously echogenic patterns.
• Previous research suggested transudative effusions are typically anechoic.
• Clinical observation indicates heterogeneous echogenic material can be present in transudative effusions.

Purpose of the Study:

• To re-evaluate the sonographic appearances of transudative pleural effusions.
• To determine the prevalence of different sonographic patterns in transudative pleural effusions.

Main Methods:

• A clinical study enrolled 127 patients with transudative pleural effusion.
• Patients met Light's criteria for transudative effusion (protein ratio <0.5, LDH ratio <0.6, fluid LDH <2/3 upper limit of normal).
• Sonographic appearances were analyzed and categorized.

Main Results:

• Transudative pleural effusions showed an anechoic pattern in 45% of cases (57/127).
• A complex nonseptated pattern was observed in 55% of cases (70/127).
• No complex septated or homogeneously echogenic patterns were found in this cohort.

Conclusions:

• Sonographic findings in transudative pleural effusions are not exclusively anechoic.
• Complex nonseptated patterns are frequent and should not preclude a diagnosis of transudate.
• In afebrile patients with bilateral effusions meeting Light's criteria, focus on treating the underlying cause, even with complex nonseptated sonographic findings.