Purpose: Free abdominal extra-luminal gas is considered an ominous clinical and radiological finding, with little data reporting the etiologies and prognosis of this entity. We investigated the causes and prognosis of extra-luminal free abdominal gas in the emergency department (ED).
Methods: We collected data for all patients who underwent abdominal-pelvic computerized tomography (CT) scan in our ED between February 2012 and February 2019. The final cohort included patients with non-loculated extra-luminal free gas. We devised a scoring system to assess for free gas amount: small – gas bubbles only; medium – any gas pocket less than 2 cm in diameter; large – any gas pocket larger than 2 cm. Laboratory results and clinical assessment regarding the source of free gas and all-cause mortality rates were collected.
Results: Our cohort included 372 patients. In the small amount group, the two most common etiologies were colonic diverticulitis (81/250; 32.4%) and normal post-operative free gas (42/250; 16.8%). In the medium amount group, colonic diverticulitis (42/250; 16.9%) and anastomotic leak (42/250; 14.1%) were the main etiologies. In the large amount group, peptic disease (42/250; 21.6%) and colonic diverticulitis (42/250; 17.6%) were the common etiologies. 280/372 patients (75.2%) had the source of free gas identified during initial ED admission. Mortality rates at 90-days post ED admission were 7.2%, 9.9% and 21.6% for small, medium and large amount groups, respectively (p=0.007), significantly higher for the large amount group.
Conclusion: Colonic diverticulitis was the most common etiology for free extra-luminal free gas, and peptic disease was the most common cause of large amount of free extra-luminal free gas. Mortality rates were significantly higher in patients with large amount of free gas.
