Patients older than 12y/o with adolescent idiopathic scoliosis planed for elective posterior scoliosis correction surgery will be enrolled for this study after informed consent. Patients will be randomly assigned to a treatment group or a control group. Functional fibrinogen will be measured using TEG 5000 (Haemoscope Corp, IL, USA) at the start of surgery and the results of FLEV and MA will be recorded. When the estimated blood loss reaches 15% of estimated blood volume, a second functional fibrinogen will be measured and the patients in treatment group will receive fibrinogen concentrate (FIBRORAAS, Shanghai RAAS Blood Products Co, Ltd, Shanghai, China) 30mg kg-1. For safety concern, the maximum fibrinogen concentrate administration for each individual shall not exceed either 2g or the results calculated based on functional fibrinogen measurements: fibrinogen concentrate dose (g) = (FLEVintraop [mg/dL] - FLEVpreop [mg/dL])×bodyweight (kg)×0.0007. Patients in the control group will receive placebo treatment with normal saline. After 15 minutes from fibrinogen concentrate or placebo administration, a third functional fibrinogen measurement will be performed to assess the effect of treatment. The following treatment will be guaranteed by the standard protocol in the presence of ongoing bleeding.