Abdominal pain

July 27, 2011

Abdominal pain is the most common gastrointestinal symptom for which medical evaluation is sought. It is a nonspecific, unpleasant sensation that can be associated with a multitude of conditions originating both within and outside the abdomen. Causes may range from common normal physiologic processes to life-threatening emergencies. There are many factors that contribute to the sensation and perception of pain, including underlying pathology, psychosocial disorders, and an individual’s pain tolerance. Thus, abdominal pain is one of the most complex complaints that clinicians encounter.

The sensation of pain is produced by mechanical stimuli, chemical stimuli, or a combination of both. The most common mechanical stimulus is stretch. There are stretch receptors located in the muscular layer of the hollow organs (gastrointestinal, urinary, and biliary tracts), mesentery (membranous attachment of intraabdominal organs to the posterior abdominal wall), and in the capsule (membranous outer covering) of solid organs (e.g., liver, spleen, kidneys). Thus, any process which leads to distention, stretching, and traction may generate abdominal pain. Chemical stimuli can increase the sensitivity of these pain receptors. Pain receptors located in the mucosa (lining of the esophagus, stomach, bladder, and intestines) are stimulated primarily by chemical stimuli released in response to local injury due to inflammation, infection, ischemia (decreased or absent blood flow), necrosis (cell death), or radiation.

Broadly speaking, abdominal pain may be produced by obstruction, inflammation, perforation, or ischemia of any hollow organ. Infection, obstruction of drainage or blood flow, and infiltration (e.g., by tumor cells) may cause capsular distention in solid organs leading to pain. Normal physiologic processes like menstruation and ovulation may also cause abdominal pain. Abdominal pain may be a feature of a number of extra-abdominal conditions including heart attack, pneumonia, testicular torsion, and a variety of metabolic disorders (e.g., lead poisoning, kidney failure). A herpes zoster flare (“shingles”) affecting a nerve that innervates the skin over the abdomen may be a misleading cause of pain before the characteristic rash appears.

Although most episodes of abdominal pain are due to mild self-limited conditions, it is essential to be able to discern the signs and symptoms that represent potential emergencies and require immediate intervention. Medical attention should be sought immediately when abdominal pain is accompanied with any of the following “alarm” signs or symptoms: red blood in the stool; maroon stool; black tarry stool; fever; sudden onset of constipation or bloating; persistent vomiting; vomiting red blood or “coffee grounds”; history of recent abdominal trauma; known or suspected pregnancy; or progressively increasing pain severity.

The clinician must interpret the complaints and physical findings in the particular context of the patient in order to first assess the level of urgency and then implement an efficient diagnostic and treatment strategy. A thorough history and physical examination is the first crucial step in the assessment of abdominal pain. Important information to be obtained are the onset of pain, location, temporal qualities (e.g., intermittent vs.

constant), radiation (e.g., to the back, shoulder, groin), relationship with gastrointestinal functions (e.g., eating, defecation), associated symptoms (e.g., fever, vomiting, jaundice, diarrhea), and any exacerbating or alleviating factors. Other characteristics include the quality of the pain (e.g., sharp, dull, cramping, or gnawing) and its severity. A detailed menstrual history in female patients should also be obtained.

The description of the onset of pain distinguishes acute abdominal pain, lasting hours to days, from chronic pain, occurring over a period of weeks to months. A perforated ulcer, dissecting aortic aneurysm, ruptured ectopic pregnancy, or kidney stones may cause pain that is sudden in onset and reaches peak severity within minutes. Acute abdominal pain that progresses to severe pain within a few hours should alert the clinician to consider acute appendicitis, cholecystitis, diverticulitis, intestinal ischemia, or intestinal obstruction. Acute abdominal pain associated with passing blood either from the upper or lower gastrointestinal tract can be a sign of ulcer disease, intestinal ischemia, or inflammatory bowel disease.

 

SEE ALSO: Chest pain, Chronic pain, Nausea, Pelvic pain, Peptic ulcer disease

Category: A, Abdominal pain