Paroxysmal episodes of intense, acute periumbilical pain that lasts for one or more hours with intervening periods of usual health lasting weeks to months, with no evidence of an inflammatory, anatomic, metabolic, or neoplastic process that explains the symptoms. The pain interferes with normal activities and is associated with at least two of the following symptoms: anorexia, nausea, vomiting, headache, photophobia, and/or pallor. [from
NCI]