CT quantification of hemoperitoneum volume in abdominal haemorrhage: a new method

In emergency departments, focused assessment for sonographic examination of trauma patients (FAST) accurately detects hemoperitoneum in unstable patients. Currently, only an approximation of the volume of free intraperitoneal fluid (FIPF) can be done using ultrasound (US) and CT scans. We previously reported a new method developed on an experimental cadaveric model using US examination of the abdomen and applying a mathematic formula to effusion measurements to evaluate the exact volume of FIPF. The aim of this prospective study is to extrapolate this method in a clinical practice and apply it to CT measurements of the same area.

We included prospectively eleven patients admitted with acute intraperitoneal haemorrhage: 10 patients with post-traumatic hemoperitoneum and 1 patient with a ruptured extra-uterine pregnancy. The mean age was 43.2 years (extremes: 21-82). There were six males and five females. All of these patients had to undergo emergency surgery by laparotomy or laparoscopy. The amount of FIPF was assessed preoperatively on axial sections of CT scan, by measuring fluid thickness in millimetres in the hepatorenal pouch (Morrison's pouch), between the inferior aspect of the liver and the anterior aspect of the right kidney. During the emergency surgical procedure, we collected and quantified FIPF volume by direct measure in all cases.

The correlation between fluid thickness x (mm) on the CT scan and the estimated amount of FIPF was established by the following linear function: volume (mL) = 81.068x + 263.2. The Spearman's R obtained is 0.779 and the significance level is 0.005. We found a constant correlation between FIPF measured by radiologic procedure and direct per-operative measurement of FIPF.

This new linear function can be used to measure the exact volume of FIPF. This evaluation can help surgical decisions, especially when abdominal trauma is associated with other haemorrhagic lesions.