Nearly everyone will experience abdominal pain at some time. Such discomfort, often called "stomach pain," can signify a transient, benign problem, or it can herald something far more serious, such as ulcers, gallbladder disease or even cancer. Pain arising within the abdominal cavity can be difficult to pinpoint. The nerve impulses relayed from the internal organs to the brain aren't well-localized, so abdominal pain can stem from anatomic, metabolic, malignant, infectious or toxic processes that originate anywhere within the abdomen or even elsewhere in the body.
The abdominal cavity is bounded at its upper end by the diaphragm and ribs, at its lower end by the pelvis, at its rear by the spine and in front by the abdominal wall. The abdominal wall consists of skin, fat, muscle and connective tissue. Lining the abdominal cavity and enclosing its contents is a thin, sensitive envelope called the peritoneum. The abdominal organs include the stomach, the large and small intestines, the liver, the gallbladder, the spleen, the pancreas, the kidneys, the urinary bladder and a host of lesser structures. Several important blood vessels pass through the abdomen, including the aorta, which is the main artery from the heart.
One peculiar property of the abdominal organs is that they don't necessarily transmit pain messages when they are sliced or cut, but they do send pain impulses when they are stretched, compressed, inflamed, twisted or, in the case of the hollow organs, when they are dilated. Anyone who has had a lot of gas after a meal, a severe bout of diarrhea, a gallbladder attack or a case of appendicitis is familiar with the types of pain that can originate in the abdomen.
Finding a Cause
When a physician evaluates a patient with abdominal pain, the patient's history and associated complaints are sometimes just as important as the physical examination itself. For example, upper abdominal pain that gets better after a meal is often caused by a stomach ulcer, while a severe, intermittent pain that moves from a patient's back, to the flank and finally to the groin could be caused by a kidney stone. And a pain that seems dull and generalized at first may eventually sharpen and settle into one specific location. This often occurs with appendicitis, which can cause vague pains around the navel until the peritoneum overlying the appendix in the lower right abdomen becomes inflamed.
Alarm Signs and Symptoms
Doctors often search for so-called "alarm signs" to help them decide if a person with abdominal pain needs urgent evaluation. Such signs include blood in the stool or vomit, anemia, persistent or severe vomiting or diarrhea, fever, weight loss, pain that awakens the patient at night and prolonged loss of appetite. A person's family history might also prompt further investigation, as in the case of individuals whose relatives have had colon cancer.
Abdominal pain that is associated with weight loss is worrisome. Cancer and inflammatory bowel disease, such as Crohn's disease or ulcerative colitis, are not infrequent causes of these two symptoms. Both inflammatory bowel disease and cancer can interfere with the absorption of nutrients from the gut, and cancer often exerts a "catabolic effect," in which tumors produce chemicals that accelerate the breakdown of fat and skeletal muscle. This can result in weight loss even when the patient is maintaining adequate food intake.
Individuals with persistent abdominal pain or pain that is accompanied by alarm signs or symptoms should seek medical attention. Abdominal pain that is associated with unexplained weight loss is especially concerning. Waiting for such pain to spontaneously resolve may delay diagnosis and treatment, and early treatment can be lifesaving for someone with cancer, infection or a problem that requires surgery.