Ultrasound demonstration of pericardial empyema in an infant with pyrexia of undetermined origin.

An infant with pyrexia of unknown origin presented to the Paediatric Unit. The initial infection screen was unhelpful and he was, therefore, referred for abdominal ultrasound to look for occult sepsis. During epigastric scanning, a large loculated fluid collection was demonstrated in the pericardium. A pericardial empyema should not be forgotten as a possible source of infection in the infant with undetermined pyrexia.