Acute idiopathic scrotal oedema: incidence, manifestations and aetiology.

Twenty-four children with a total of 31 episodes of acute idiopathic scrotal oedema (AISO) were assessed during a 5 year period. AISO accounted for 30 per cent of all admissions with acute scrotal pathology in this period and was the final diagnosis in 69 per cent of cases in those presenting under the age of 10 years. Although presentation was with unilateral (48 per cent) or bilateral (52 per cent) AISO, considerable overlap between these two groups occurred. Five patients (21 per cent) had recurrent attacks. Fourteen boys (60 per cent) had a history of allergy or had allergic manifestations at presentation compared with an incidence of allergy of 28 per cent in 42 controls (P less than 0.05). AISO is the commonest cause of the 'acute scrotum' in boys under the age of 10 years and is probably allergic in origin.