CT in patients with blunt abdominal trauma: clinical significance of intraperitoneal fluid detected on a scan with otherwise normal findings.

OBJECTIVE: The purpose of this study was to determine the clinical significance of intraperitoneal fluid seen on CT scans with otherwise normal findings in patients with blunt abdominal trauma.
MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 60 patients with blunt abdominal trauma who had scans showing normal findings except for the presence of intraperitoneal fluid. The location of the fluid was determined (pouch of Douglas, pelvis, paracolic gutters, mesentery, Morison's pouch, perihepatic or perisplenic spaces). The amount of fluid in each location was categorized as minimal, moderate, or marked. The total volume of fluid in each patient was estimated as small (+1), intermediate (+2), or large (+3) on the basis of the sum of the amount of fluid in the individual peritoneal locations. The amount and location of fluid were compared between patients who required exploratory laparotomy and those who were managed conservatively.
RESULTS: In most patients, the total fluid volume was small (44 patients, 73%) as opposed to intermediate (11 patients, 18%) or marked (five patients, 8%). Thirty-seven patients had fluid in one location, 12 patients had fluid in two locations, and 11 patients had fluid in three or more locations. Intraperitoneal fluid tended to accumulate in the pouch of Douglas (67%) and Morison's pouch (33%). Patients requiring laparotomy had a higher total fluid volume score compared with the patients managed conservatively (2.2 versus 1.3, p < .002) and had larger amounts of fluid in the upper abdomen. Laparotomy was required in only one patient (2%) who had a small amount of fluid compared with three patients (27%) with intermediate and two patients (40%) with marked amounts. Mesenteric and/or bowel injuries were noted in all six patients at laparotomy. One patient had a small superficial liver laceration that was not diagnosed with CT. No other injuries to the solid viscera were missed on the scans. Two of the four patients with mesenteric fluid seen on the CT scan had mesenteric lacerations found during surgery, and the remaining two did well with conservative management.
CONCLUSION: Patients with blunt abdominal trauma who have small amounts of intraperitoneal fluid as the sole abnormality shown by CT may generally be treated conservatively. However, patients with even a small quantity of mesenteric fluid may benefit from peritoneal lavage to help exclude bowel or mesenteric injury. Intermediate and large amounts of fluid are less common as the sole CT abnormality but have a higher likelihood of being associated with bowel or mesenteric injury.