Peritoneal fluid of low CT Hounsfield units as a screening criterion for traumatic bowel perforation

Purpose: To investigate whether peritoneal fluid of low CT Hounsfield units is an important screening criterion for traumatic bowel perforation. Materials and methods: We performed a retrospective study on two cohorts of blunt trauma patients who had peritoneal fluid. Intravenous and oral contrast was used for the first cohort (61 patients) as opposed to intravenous contrast only for the second cohort (60 patients). We compared the CT Hounsfield units of peritoneal fluid with bowel perforation. The optimal cutoff value of CT Hounsfield units was determined, and its diagnostic values for bowel perforation were calculated. Results: The mean CT Hounsfield units (HU) of peritoneal fluid with bowel perforation were significantly lower (30.3 ± 9.0 versus 44.1 ± 13.6 HU, p = 0.008) in the second cohort. The optimal cutoff value was 43 HU, and its sensitivity, specificity, accuracy and positive likelihood ratio were 100.0, 69.2, 73.3% and 3.3, respectively, for bowel perforation. Comparisons of CT HUs of peritoneal fluid with bowel perforation in the first cohort that used additional oral contrast for CT did not show statistically significant differences. Conclusion: Peritoneal fluid of low CT HU is a sensitive and important CT screening criterion for traumatic bowel perforation.