Combination of dirty mass volume and APACHE II score predicts mortality in patients with colorectal perforation

BACKGROUND: “Dirty mass” is a specific computed tomography (CT) finding that is seen frequently in colorectal perforation. The prognostic significance of this finding for mortality is unclear. METHODS: Fifty-eight consecutive patients with colorectal perforation who underwent emergency surgery were retrospectively reviewed in the study. Dirty mass identified on multi-detector row CT (MDCT) was 3D-reconstructed and its volume was calculated using Ziostation software. Dirty mass volume and other clinical characteristics were compared between survivor (n = 45) and mortality groups (n = 13) to identify predictive factors for mortality. Mann–Whitney U test and Χ(2) test were used in univariate analysis and logistic regression analysis was used in multivariate analysis. RESULTS: Dirty mass was identified in 36/58 patients (62.1%) and located next to perforated colorectum in all cases. Receiver-operating characteristic (ROC) curve analysis identified the highest peak at 96.3 cm(3), with sensitivity of 0.643 and specificity of 0.864. Univariate analysis revealed dirty mass volume, acute disseminated intravascular coagulation (DIC) score, acute physiology and chronic health evaluation II (APACHE II) score, and sequential organ failure assessment (SOFA) score as prognostic markers for mortality (p<0.01). Multivariate analysis revealed dirty mass volume and APACHE II score as independent prognostic indicators for mortality. Mortality was stratified by dividing patients into four groups according to dirty mass volume and APACHE II score. CONCLUSIONS: The combination of dirty mass volume and APACHE II score could stratify the postoperative mortality risk in patients with colorectal perforation. According to the risk stratification, surgeons might be able to decide the surgical procedures and intensity of postoperative management.