Purpose: We analyzed radiography and computed tomography (CT) findings of small bowel perforation due to blunt trauma to identify the keys to diagnosis.
Materials and methods: Twelve patients with surgically proven small bowel perforation were retrospectively studied. All patients underwent radiography and CT, and five underwent presurgical follow-up CT. Radiological findings were evaluated and correlated to the elapsed time from the onset of the trauma retrospectively.
Results: Radiography demonstrated free air in only 8% (1/12) and 25% (3/12) at the initial and follow-up examinations, respectively. In contrast, the initial and follow-up CT scans detected extraluminal air in 58% (7/12) and 92% (11/12), respectively. Mesenteric fat obliteration was seen in 58% (7/12) and 75% (9/12) at initial and follow-up CT, respectively. The incidence of both extraluminal air and mesenteric fat obliteration on CT increased as time elapsed, particularly after 8 h. High-density ascites was seen in 75% at initial CT, including two patients without extraluminal air, but was observed in all but one patient at follow-up CT.
Conclusion: The chance of detecting extraluminal air increases as time elapses. High-density ascites may be seen without extraluminal air and might be an indirect or precedent sign of small bowel perforation. Radiologists need to be familiar with these radiological features.