Retained surgical sponges, euphemistically called 'Gossypibomas', are rare occurrences which are infrequently reported in the literature because of legal implications. Their manifestations and complications are so variable that diagnosis is difficult and patient morbidity is significant. In this note, we discuss the classical ultrasound, computerized tomography (CT) scanning and magnetic resonance imaging (MRI) features, which, in the presence of a high index of suspicion in a patient who has previously been operated upon, will greatly aid in the pre-operative diagnosis of this unfortunate complication. The gossypiboma masquerading as a perinephric abscess has not been previously reported.