Objective:To observe the effect of fluid therapy on volume and coagulation function in patients with severe postpartum hemorrhage during cesarean section of placenta accreta under the guidance of inferior vena cava diameter (IVCD) and inferior vena cava collapse index (IVC-CI).Methods:A prospective randomized controlled study was conducted in 60 pregnant women with severe postpartum hemorrhage (blood loss ≥ 1 000 mL) who were hospitalized for delivery or referred for delivery in the Peking University Third Hospital from December 2018 to July 2019. The patients were divided into routine fluid replacement group and goal-oriented fluid resuscitation group (goal-oriented fluid replacement therapy was given) according to the different ways of fluid replacement. The hemodynamics, blood gas analysis, coagulation function, total fluid replacement, urine volume, prognosis, intraoperative vasoactive drugs utilization rate and postoperative adverse events were recorded before skin incision, after the fetus delivered, postpartum hemorrhage and at the end of operation, and the differences of these indices between the two groups were compared.Results:① Hemodynamics: the heart rate (HR) of the two groups were reached the peak during postpartum hemorrhage, but there was no significant difference in HR at each time point between the two groups. The mean arterial pressure (MAP) was decreased at first and then increased in both groups, and reached the trough at postpartum hemorrhage, but the MAP in the goal-oriented fluid resuscitation group was significantly higher than that in the routine fluid replacement group [mmHg (1 mmHg = 0.133 kPa): 75.6±10.7 vs. 69.2±8.9, P < 0.05]. In the goal-oriented fluid resuscitation group, the central venous pressure (CVP) was increased slightly after the fetus delivered and then stabilized, while in the routine fluid replacement group, the CVP was increased at first and then decreased, and reached the peak in postpartum hemorrhage. During postpartum hemorrhage, CVP in the goal-oriented fluid resuscitation group was significantly lower than that in the routine fluid replacement group [cmH 2O (1 cmH 2O = 0.098 kPa): 9.5±3.9 vs. 11.4±3.4, P < 0.05]. ② Arterial blood gas: partial pressure of oxygen (PaO 2) and partial pressure of carbon dioxide (PaCO 2) in arterial blood at the end of operation in both groups were higher than those in postpartum hemorrhage. There was no significant difference in PaO 2 at the end of operation between the goal-oriented fluid resuscitation group and routine fluid replacement group (mmHg: 189.3±100.5 vs. 240.2±126.3, P > 0.05). The PaCO 2 in the goal-oriented fluid resuscitation group was significantly lower than that in the routine fluid replacement group (mmHg: 34.6±4.6 vs. 36.8±4.1, P < 0.05). The lactic acid (Lac) at the end of operation of the goal-oriented fluid resuscitation group was significantly lower than that of the routine fluid replacement group (mmol/L: 2.2±0.6 vs. 2.6±1.1, P < 0.05). ③ Liquidintake and output volume: the total infusion volume, crystal fluid infusion volume and suspended red blood cell infusionvolume in the goal-oriented fluid resuscitation group were significantly less than those in the routine fluid replacement group [total infusion volume (mL): 3 385.9±1 144.1 vs. 4 448.3±1 194.4, crystal infusion volume (mL): 2 635.6±789.7 vs. 3 160.0±860.3, suspended red blood cell input volume (mL): 695.6±366.2 vs. 911.1±284.7, all P < 0.05], and the utilization rate of vasoactive drugs in the goal-oriented fluid resuscitation group was decreased significantly during operation [13.3% (4/30) vs. 60.0% (18/30), P < 0.05]. The amount of bleeding in the goal-oriented fluid resuscitation group was also significantly less than that in the routine fluid replacement group (mL: 1 451.7±373.8 vs. 1 725.9±372.8, P < 0.05), but there was no significant difference in urine volume between the goal-oriented fluid resuscitation group and the routine fluid replacement group (mL: 369.0±262.7 vs. 485.0±286.8, P > 0.05). ④ Coagulation function: at the end of operation, the prothrombin time (PT) in the goal-oriented fluid resuscitation group was significantly shorter than that in the routine fluid replacement group (s: 10.9±0.6 vs. 11.2±0.6), and the fibrinogen (Fib) in the goal-oriented fluid resuscitation group was significantly higher than that in the routine fluid replacement group (g/L: 3.7±0.5 vs. 2.9±0.8), and the differences were statistically significant (both P < 0.05).⑤ Prognostic index: compared withthe routine fluid replacement group, the proportion of patients transferred to intensive care unit (ICU) at the end of operation in the goal-oriented fluid resuscitation group was significantly lower [16.7% (5/30) vs. 66.7% (20/30), P < 0.05], and ICU length-of-stay was significantly shorter [hours: 0 (0, 24) vs. 24 (0, 24), P < 0.05], but there was no significant difference in the incidence of disseminated intravascular coagulation (DIC), acute renal injury (AKI) or hysterectomy between the goal-oriented fluid resuscitation group and the routine fluid replacement group [the incidence of DIC: 0% (0/30) vs. 6.7% (2/30), the incidence of AKI: 0% (0/30) vs. 3.3% (1/30), the hysterectomy rate: 10.0% (3/30) vs. 26.7% (8/30), all P > 0.05]. Conclusion:Fluid resuscitation guided by IVC-CI can effectively reduce the volume of blood and fluid transfusion and blood loss in patients with severe postpartum hemorrhage and improve their blood coagulation function.