ObjectiveTo compare the pelvis free liquid quantity deepness measured by ultrasound and actual blood volume in abdominal cavity observed during operation in ectopic pregnancy patients, so as to predict the pre-operation intra-abdominal hemorrhage volume. MethodsFive hundred patients with ectopic pregnancy receiving emergent operation were included in the present study. The patients took lithotomy position and were examined by vaginal probe before operation. The pelvis free liquid quantity measured by ultrasound (x) and the actual blood volume in abdominal cavity (y) observed during operation were subjected to statistical analysis using SPSS 16.0 software. ResultsThe pelvis free liquid measured by ultrasound and the actual quantity of blood in abdominal cavity accorded with the following equation: y=43.306 e0.704x, R2=0.983, P＜0.05.The actual volume of blood in pelvis could be calculated by the equation. When the quantities of free liquid in pelvis were 3 cm, 3.5 cm, 4.0 cm, and 4.5 cm, the actual volumes of blood in pelvis were 357.91 ml, 508.92 ml, 732.64 ml, and 1 028.95 ml, respectively. ConclusionThe quantity of intra-abdominal hemorrhage can be predicted by the pelvis free liquid deepness in ectopic pregnancy patients, which may pave a way for more effective treatment of the patients.