Editor,—Acute appendicitis is the most common surgical emergency in children, estimated to occur at a rate of 4 per 100 per annum. Its prompt diagnosis is important because the risk of perforation increases with time, occurring in 10% of patients by 24 hours and up to 50% by 48 hours.1 The technique for renal transplantation in children is similar to that in adults, the extraperitoneal placement of the kidney being sited in the right (or more rarely left) iliac fossa (RIF). The renal artery is anastomosed to the common iliac artery or aorta and the renal vein to the external iliac vein or inferior vena cava. The differential diagnosis of RIF pain in this group of children …