Acute hemoperitoneum in children: prevalence of low-attenuation fluid

Background. Recent evidence indicates that acute hemoperitoneum may have lo wer than expected attenuation values at CT. Objective. To characterize the attenuation of acute hemoperitoneum at CT in children following blunt abdominal trauma and to assess the prevalence of low-attenuation fluid. Materials and methods. The CT scans of 19 consecutive children with isolate d hepatic or splenic injury and associated peritoneol fluid were retrospect ively analyzed. The attenuation value of peritoneal fluid was assessed in a ll peritoneal spaces. Results. Fluid was noted in 53 peritoneal spaces (27 abdominal, 26 pelvic). Fluid attenuation ranged from 20 to 64 HU. The mean fluid attenuation in p elvic spaces (37.5 +/- 9.4 HU) was significantly lower than in abdominal sp aces (444.9 +/- 10.2 HU) (P = 0.008), Fluid in 8/26 (31 %) pelvic spaces an d 2/27 (7%) abdominal spaces had attenuation values less than or equal to 3 0 HU, Fluid surrounding the site of injury (perihepatic or perisplenic spac e) was significantly higher in attenuation than fluid at other sites (P < 0 .001), There was no correlation between the mean attenuation value of perit oneaI fluid in each patient and the admission hematocrit (r = -0.14, P = 0. 55). Conclusions. There is great variability in the attenuation of acute hemoper itoneum. Blood in pelvic spaces has significantly lower attenuation than bl ood in abdominal spaces. Hemoperitoneum in the pelvis has values of less th an or equal to 30 HU in approximately one-third of spaces. The attenuation of acute hemoperitoneum does not correlate with hematocrit.