The abdominal wall: an overlooked source of pain.

When abdominal pain is chronic and unremitting, with minimal or no relationship to eating or bowel function but often a relationship to posture (i.e., lying, sitting, standing), the abdominal wall should be suspected as the source of pain. Frequently, a localized, tender trigger point can be identified, although the pain may radiate over a diffuse area of the abdomen. If tenderness is unchanged or increased when abdominal muscles are tensed (positive Carnett's sign), the abdominal wall is the likely origin of pain. Most commonly, abdominal wall pain is related to cutaneous nerve root irritation or myofascial irritation. The pain can also result from structural conditions, such as localized endometriosis or rectus sheath hematoma, or from incisional or other abdominal wall hernias. If hernia or structural disease is excluded, injection of a local anesthetic with or without a corticosteroid into the pain trigger point can be diagnostic and therapeutic.