Up to a certain depth, ultrasound provides a higher resolution than the CT. Thus, subtle structures can be resolved by ultrasound – e.g. detection of septations in effusions is better when using ultrasound.
Current ultrasonographic equipment possesses such qualitative imaging possibilities that even effusions without septations may be echogenic (e.g. due to a higher amount of proteins in effusion). Thus, distinguishing between exudate, transudate and even empyema may not be trivial.
Your patient suffers from pneumonia complicated with parapneumonic effusion. Correct distinguishing between complicated and uncomplicated parapneumonic effusion results in different therapeutic approaches. Thus, the characteristics of effusion should be assessed by a puncture. The safe puncture should be performed with the help of sononavigation.
Does this patient (suffering from recurrent unilateral pleural effusion) present with transudate or exudate?