I have pleura liquid in both of my lungs. i had an operation and doctors took sample from the liquid pleura, everyting is fine but no root cause found?

Pleural effusion.: If no etiology for the pleural effusion was identified on the first pass, then another round of thinking and testing may be necessary. A pleural effusion is not a diagnosis unto itself - it hints to another process occurring - this process needs to be identified. You should revisit your doctor and continue investigations until an answer, or list of answers, is reached.