that may radiate to the lower back. The pain may worsen when the patient lies down and may be relieved
when he leans forward or sits up. Before rupture, the aneurysm may produce a pulsating mass in the
epigastrium, accompanied by a systolic bruit over the aorta. However, the mass stops pulsating after
rupture. Associated signs and symptoms include mottled skin below the waist, absent femoral and pedal
pulses, blood pressure that's lower in the legs than in the arms, and mild to moderate abdominal tenderness
with guarding. Significant blood loss causes signs of shock, such as tachycardia, tachypnea, and cool,
clammy skin.
♦ Mesenteric artery ischemia. This lifethreatening disorder is characterized by 2 to 3 days of persistent,
low-grade abdominal pain and diarrhea leading to sudden, severe abdominal pain and rigidity. Rigidity
occurs in the central or periumbilical region and is accompanied by severe abdominal tenderness, fever,
and signs of shock, such as tachycardia and hypotension. Other findings may include vomiting, anorexia,
diarrhea, and constipation. Always suspect mesenteric artery ischemia in patients older than age 50 who
have a history of heart failure, arrhythmias, cardiovascular infarct, or hypotension.
♦ Peritonitis. Depending on the cause of peritonitis, abdominal rigidity may be localized or generalized.
For example, if an inflamed appendix causes local peritonitis, rigidity may be localized in the right lower
quadrant. If a perforated ulcer causes widespread peritonitis, rigidity may be generalized and, in severe
cases, boardlike.
Peritonitis also causes sudden and severe abdominal pain that can be localized or generalized. It can also
produce abdominal tenderness and distention, rebound tenderness, guarding, hyperalgesia, hypoactive or
absent bowel sounds, nausea, and vomiting. Most patients also experience fever, chills, tachycardia,
tachypnea, and hypotension.
♦ Pneumonia. In lower lobe pneumonia, severe upper abdominal pain and tenderness accompany rigidity
that diminishes with inspiration. Associated signs and symptoms include blood-tinged or rusty sputum,
dyspnea, achiness, headache, fever, sudden onset of chills, crackles, egophony, decreased breath sounds,
dullness on percussion, and a dry, hacking cough.
OTHER CAUSES
♦ Insect toxins. Insect stings and bites, especially black widow spider bites, release toxins that can produce
generalized cramping abdominal pain, usually accompanied by rigidity. These toxins may also cause low-
grade fever, nausea, vomiting, tremors, and burning sensations in the hands and feet. Some patients
develop increased salivation, hypertension, paresis, and hyperactive reflexes. Children commonly are
restless, have an expiratory grunt, and keep their legs flexed.
SPECIAL CONSIDERATIONS