Acute abdominal pain in an elderly patient
A possible large bowel obstruction and severe dehydration prompted us to admit this patient. But a day later, the clinical picture became even more worrisome.
Diagnosis: Pneumoperitoneum
This patient had free air under her diaphragm (due to a viscus perforation) and concomitant septic shock. Free air in the peritoneal cavity—pneumoperitoneum— indicates visceral perforation in 85% to 95% of cases.1,2 A ruptured intra-abdominal viscus is considered a surgical emergency. Pneumoperitoneum is often linked to peptic ulcer disease and is seen in 50% of cases of bowel perforations.3 This condition has a higher prevalence in the elderly and carries a higher mortality rate (up to 30% compared with 19% in a younger population).4
A picture that shifts according to the patient’s age
Physical findings suggestive of visceral perforation include sharp abdominal pain with a rigid abdominal wall. Patients will usually lie still because of the peritoneal irritation. Tachycardia and tachypnea are seen early in the disease process, while hypotension and fever usually develop within 4 to 6 hours.5
Elderly patients, however, can present with milder or nonspecific symptoms. Rather than pain, they may complain of the urge to defecate. Physical exam findings such as tachycardia or fever can also be absent due to autonomic dysregulation or medication. Furthermore, laboratory analysis is commonly within normal limits, making the diagnosis even more challenging in this population.5,6
Imaging confirms the Dx
The standard imaging test used to confirm pneumoperitoneum is a standing chest x-ray that will detect free air in almost 80% of cases.7 The sensitivity is influenced by the location of the perforation: Free air will be seen in 69% of gastroduodenal perforations, 30% to 41% of distal small bowel perforations, and 37% to 46% of large bowel perforations.1 Abdominal computed tomography scans have been reported to be more sensitive (up to 100%), especially in identifying small pneumoperitoneum.8,9
