Isolated free fluid on computed tomography for blunt abdominal trauma - A South African Experience

INTRODUCTION The clinical significance of isolated free fluid on abdominal computed tomography (CT) in patients with blunt abdominal trauma is unclear. This audit reviews our unit's experience with isolated free fluid and attempts to refine our clinical algorithms for the assessment of patients with blunt abdominal trauma. MATERIALS AND METHODS All patients who sustained blunt abdominal trauma between December 2012 and December 2017 who were subjected to multidetector CT of the abdomen as part of their initial investigation were included in this study. RESULTS During the five-year period under review, a total of 1066 patients underwent abdominal CT following blunt poly trauma. A total of 84 (7.9%) patients died. There were 148 (14%) patients with CT finding of isolated free fluid. Of these, 128 (67%) were selected for non-operative management, which included a period of serial abdominal examinations. In this non-operative group, five patients failed their abdominal observations and underwent laparotomy. Findings in these five cases were negative (1), non-therapeutic (1), splenic injury (1), Pancreatic and splenic injury (1) and bladder injury (1). Thirteen patients (10%) died, none of whom had surgery. The causes of death were exsanguination from a major traumatic lower limb injury (1), multiple organ failure (1), traumatic brain injury (10) and spinal cord injury (1). The remaining 20 patients underwent laparotomy. The indications were failed non-operative management (5), abdominal distension (1) and suspicion of a missed hollow viscus injury (14). In this group there were 11 therapeutic and 6 non-therapeutic surgeries and three negative laparotomies. For the 15 patients selected for operative management, the findings were as follows: hollow viscus injury (3), mesenteric bleeds (2), splenic and pancreatic injury (1), liver and bladder injury (1), splenic and bladder injury (1), non-therapeutic (4), negative (3). The finding of isolated free fluid on CT is 98% sensitive and 96% specific for true isolated free fluid (chi square 331.598; P= 0.000). This finding predicts successful non-operative management with a positive predictive value of 93% and a negative predictive value of 96%. DISCUSSION In patients with blunt abdominal trauma, the finding of isolated free fluid on abdominal CT alone is no longer an indication for laparotomy. Other clinical factors must be taken into account when deciding on the need for laparotomy, such as haemodynamic status, clinical abdominal findings and the ability to reliably assess the abdomen. In the absence of a clinical indication for urgent laparotomy, patients with isolated free fluid may be observed.