This is Henoch-Schonlein purpura.The condition is a small vessel vasculitis usually affecting children but also, occasionally, adults. The purpuric rash usually appears on the buttocks and thighs. It can be associated with arthralgia, haematuria and abdominal pain with GI haemorrhage, intussusception and obstruction. It is an uncommon cause of acute abdomen, the pain being due to bleeding within the bowel wall, leading to intussusception .