Qualitative and quantitative analysis of post-operative drainage: pilot study

Surgical drains can be placed after an operation to collect postoperative blood loss. However, these could be overestimated. Indeed, the fluid elapsed after the first postoperative day would no longer be pure blood. An early withdrawal of redon could then be considered. A monocentric prospective study of 25 patients undergoing total knee or primary hip replacement surgery, for osteo-arthritis, was conducted. Redon flow was evaluated in total volume and in composition by the sedimentation study. A qualitative analysis of the content of the redon was also carried out. To compare the elements found in the drained liquid with the blood data, a preoperative and two postoperative blood samples were taken. 18 TKA and 7 THA were included. A qualitative analysis of the postoperative flow of 11 TKA and 5 THA was requested. Decreases of sedimentation volumes and protein levels were found in the drained liquid compared to the blood for both TKA and THA. Our results tend to prove that on postoperative D1, the liquid drained in the redon would be blood, but that the liquid drained on D2 and D3 would be a mixture of blood and serum. Therefore, the real postoperative blood loss would be overestimated.