Is serum C-reactive protein a reliable predictor of abdomino-pelvic CT findings in the clinical setting of the non-traumatic acute abdomen?

The aim of this study was to determine if serum C-reactive protein (CRP), an acute phase reactant which exhibits a rapid rise in serum in inflammatory conditions, is a reliable predictor of abdomino-pelvic CT findings in the clinical setting of the non-traumatic acute abdomen. All patients presenting with symptoms of acute abdominal pain to a level-1 emergency department over a 12-month period were included. Patients with serum CRP measured on admission and within 24 h of the abdomino-pelvic CT scan were subselected and those with a history of recent surgery, malignancy, and inflammatory bowel disease were excluded (n = 241). CT findings were graded in consensus by two radiologists and visceral adipose volume and severity of adipose stranding were also assessed. Statistical analysis was performed using SPSS v17. Positive imaging findings were evident on 176 CTs (73 %). There were equal numbers of positive and negative CT scans in patients with low serum level of CRP (0-5 mg/L). As CRP level increased the proportion of positive CTs increased (p < 0.001, Chi-square test for trend). The likelihood ratio for positive CT findings in patients with a CRP level greater than 130 mg/L was 3.45 with reported specificity and sensitivity of 90.9 and 31.4 %, respectively. A low CRP level (0-5 mg/L) does not out rule positive findings on CT in the clinical setting of the acute abdomen. Increasing levels of CRP predict, with increasing likelihood, positive findings on CT.