Ureteropelvic junction obstruction: an overlooked cause of cyclic vomiting

Cyclic vomiting syndrome is an unusual cause of recurrent episodes of repetitive vomiting, particularly in children. Although in only a minority of cases can an underlying cause be found, each patient deserves a thorough evaluation for treatable conditions. We present four cases of cyclic vomiting syndrome caused by ureteropelvic obstruction. Surgical correction was followed by resolution of symptoms in all four patients.