A new method to approach exact hemoperitoneum volume in a splenic trauma model using ultrasonography

In the trauma setting, the Focused Assessment for the Sonographic examination of the Trauma patient (FAST) accurately detects hemoperitoneum. Currently, only an approximate evaluation of the volume of free intraperitoneal fluid (FIPF) can be done by imaging modalities such as ultrasound (US). The aim of this study was to correlate the thickness of FIPF measured by US in different sites of the peritoneal cavity with the total volume of an experimental post-traumatic hemoperitoneum. An intra-abdominal collection with ongoing bleeding was simulated in eight cadavers with no previous abdominal surgery. Between 200 and 2000 ml of saline solution was instilled into the left hypochondrium of eight non-embalmed cadavers. During the instillation, FIPF thickness was measured every 200 ml by US in six different declivous sites of the peritoneal cavity. The volume of FIPF instilled could be mathematically correlated with fluid thickness in all the sites through the linear equation Y=aX+b, where Y is the volume of FIPF in milliliters, a is 33 (variability coefficient), X is the FIPF thickness in millimeters and b is 470 ml (minimum volume detectable by US). The best correlation between thickness and volume was obtained in the hepatorenal pouch (Morrison pouch). Evaluation of the impact of intraperitoneal hemorrhage on the hemodynamic state of spleen trauma patients is of paramount importance for the surgeon, who has to decide whether to perform a laparotomy for hemostasis or not, specially when intra- and extra-abdominal injuries conjointly exist. After clinical validation, this new method to calculate the exact volume of FIPF could be used in current clinical practice of abdominal trauma to assist in the decision-making regarding non-operative treatment of spleen trauma.