Severe Respiratory Syncytial Virus Bronchiolitis Complicated by Bilateral Massive Pleural Effusions in a Previously Healthy Infant: A Case Report.

Respiratory syncytial virus (RSV) bronchiolitis is one of the leading causes of hospitalization in infants, typically presenting with mild-to-moderate respiratory distress. Severe complications such as apnea, respiratory failure, and pneumothorax are known, but massive pleural effusions remain an exceptionally rare manifestation. We report a case of an eight-week-old previously healthy Saudi female infant presenting with severe RSV bronchiolitis. The patient developed progressive respiratory failure requiring mechanical ventilation, re-intubation, and circulatory support. Notably, she developed bilateral massive pleural effusions necessitating urgent bilateral pigtail catheter insertion. Pleural fluid was sterile and transudative in nature. The infant showed significant clinical improvement following drainage and supportive care, with eventual full recovery. This case highlights an unusual but severe complication of RSV bronchiolitis. It underscores the need for clinicians to consider pleural effusion in infants with RSV who deteriorate despite supportive measures, even in the absence of bacterial infection.