Chronic Abdominal Pain

Pain receptors in the abdomen respond to mechanical and chemical stimuli. Stretch is the principal mechanical stimulus involved in visceral pain and is brought on by distension and contraction. Different types of chemical and physical causes can work together to make you feel abdominal pain and the threshold for perceiving pain varies among patients. Chronic pain may be triggered by an initial insult, and for some people, normal physiological processes such as digesting food can be felt as painful. Visceral hyperalgesia may predispose to chronic pain even after the initial cause has resolved. 

Pain originating in the organ walls can often be perceived to come from a distant site, this is known as referred pain. Referred pain usually is located in the skin’s dermatomes at the causative organ’s spinal levels, or can be from an organ pushing on a nerve that travels elsewhere in the body and causes pain at the distal site. A classic example of this pain is an inflamed gallbladder being perceived as aching scapula (posterior shoulder).