Unusual causes of abdominal pain.

Common and uncommon GI and other intraperitoneal illnesses may present in unusual ways. In addition, many systemic or extraperitoneal disease processes frequently include abdominal pain as a clinical manifestation. The clinician should suspect an unusual cause of abdominal symptoms in patients with repeated visits to the ED without a diagnosis, those who appear ill or complain of severe abdominal pain with disproportionately negative abdominal physical examination findings, those with constitutional or extraperitoneal symptoms or signs, and the elderly or immunocompromised. After initial resuscitation and stabilization have taken place, early evaluation of the need for urgent surgical evaluation and operative management is crucial in the patient with abdominal pain, even when the cause of the symptoms is unclear. A thorough history and careful and complete abdominal and nonabdominal physical examination, paired with appropriate but judicious diagnostic testing, are essential to detecting these unusual causes of abdominal pain and to preventing needless morbidity and mortality.