Hidden blood loss after total hip arthroplasty.

A prospective study was carried out to analyze the characteristics of hidden blood loss after total hip arthroplasty (THA) in a series of 1232 patients. The method of deducting the observed perioperative blood loss from the calculated total blood loss based on hematocrit changes was used to calculate the hidden blood loss of each patient. The reinfused and transfused bloods were also considered. We found that the amount of hidden blood loss after THA was much larger than we observed perioperatively and significantly different between differently diagnosed patients. We concluded that THA can cause a large amount of hidden blood loss, which should be monitored carefully. Retaining and repairing the articular capsule is recommended during the operation, which can significantly decrease hidden blood loss.