Abstract
Although pleural effusion is a frequent finding in clinical practice, determining its aetiology may be challenging, and up to 20% of cases remain undiagnosed. Pleural effusion may occur secondary to a nonmalignant gastrointestinal disease. A gastrointestinal origin is confirmed based on a review of the medical history of the patient, thorough physical examination and abdominal ultrasonography. In this process, it is crucial to correctly interpret findings on pleural fluid obtained by thoracentesis. In the absence of high clinical suspicion, identifying the aetiology of this type of effusion may be difficult. Clinical symptoms will be determined by the gastrointestinal process causing pleural effusion. In this setting, correct diagnosis relies on the specialist's ability to evaluate pleural fluid appearance, test for the appropriate biochemical parameters and determine whether it is necessary or not to send a specimen for culture. The established diagnosis will determine how pleural effusion is approached. Although this clinical condition is self-limited, many cases will require a multidisciplinary approach because some effusions can only be resolved with specific therapies.