CHARACTERISTICS OF ABDOMINAL PAIN



Abdominal pain usually takes one or a combi­nation of three patterns: (1) Visceral pain is usu­ally dull, poorly localized due to the multiseg-mental bilateral innervation of abdominal organs, and often midline in location. It originates in an abdominal viscus and may have a crampy orgnawing quality. (2) Parietal (somatic) pain is in­tense, often well-localized and lateralized. The pain is due to stimulation, usually inflammatory in nature, of the parietal peritoneum. (3) Referred pain is localized superficial or deep pain per­ceived in areas remote from the diseased viscus and innervated by the same spinal segment. The pain is sometimes associated with hyperesthesia.

Although visceral pain is usually poorly local­ized, certain useful generalizations can be made. Pain from the esophagus is usually substernal, may be discretely localized, and, if severe, may penetrate to the middle of the back or the left arm. Pain from the stomach, duodenum, and pancreas is epigastric, often with radiation to the back. Liver, gallbladder, and bile duct pain may be epi­gastric but is usually located in the right upper quadrant. Gallbladder or biliary pain may be re­ferred to the tip of the scapula. Pain from a sub­phrenic abscess or hepatic abscess may be referred to the shoulder tip. Jejunal and ileal pain is often periumbilical, although terminal ileal pain may be felt in the right lower quadrant. Colonic pain is poorly localized but is usually felt in the lower abdomen or hypogastric area, as is pain from the pelvic organs. Finally, rectal pain may be felt over the sacrum. Unusual but diagnostically important patterns of abdominal pain include angina-like left upper quadrant discomfort from the trans­verse colon, and left back/hip pain resembling L4 root disease or ovarian disease but emanating from the transverse or the descending colon. Pos­terior appendiceal rupture sometimes produces similar pain in the right lumbar-gluteal area.

The quality and progression of pain may also be helpful. The pain of esophageal reflux (heart­burn) is usually burning in nature, whereas the characteristic pain of peptic ulcer disease gnaws or burns and often subsides following ingestion of food or antacids. Pain due to bowel obstruction is described as recurrent, severe, and cramping (colic), often interposed with short periods of lit­tle or no pain. Furthermore, patients with bowel colic pain are often restless. In contrast, the term biliary colic is a misnomer, as the pain associated with cystic duct obstruction is usually steady rather than intermittent in nature. Pain due to in­flammation, particularly of the parietal perito­neum, transmits a steady quality, felt locally, if the peritoneum is irritated focally by an under­lying diseased organ such as an inflamed appen­dix or gallbladder, or diffusely if material such as gastric juice, intestinal contents, blood, or pus has leaked into the peritoneal cavity. Peritoneal irritation is accompanied by tenderness, by guarding {voluntary tensing) and rigidity [involuntary spasm) of the overlying abdominal muscles, and by rebound tenderness. Such patients usually lie still to minimize the discomfort. Pain due to in­testinal ischemia is usually severe, poorlv local­ized and steady, often with little abdominal ten­derness in the early stages. The pain related to dissection of an abdominal aortic aneurysm oc­curs suddenly and is severe and often described as “tearing.” Some types of abdominal pain change characteristically with time. For example, sudden severe pain that subsequently becomes generalized con­comitant with the appearance of signs of perito­neal irritation suggests that a hollow viscus has perforated to cause generalized peritonitis. In con­trast, the pain of acute appendicitis or cholecys­titis may begin as a poorly localized midline pain that later moves directly over the inflamed organ as localized peritoneal inflammation develops.