[Impact of blood reserve tests in bariatric surgery: How necessary and how routine?]

Preoperative blood ordering is frequently in bariatric surgery, even for procedures that rarely require blood transfusion. The aim of this study was to evaluate the patients who receive transfusion and determining their associated factors and assess the need to make a pre-operative blood reserve test in elective bariatric surgery based on the rational analysis of over-reserve, risk-benefit and cost-effectiveness.

A retrospective review was conducted on consecutive patients who underwent bariatric surgery between 2020 and 2024. Clinical-pathological and surgical variables were analyzed. The crossmatch-to-transfusion ratio, probability of transfusión, and transfusion index were calculated.

A total of 174 patients underwent bariatric surgery. Only one patient required a blood transfusion, yielding a transfusion probability of 0.57%, a crossmatch-to-transfusion ratio of 88, and a transfusion index of 0.02. None of the analyzed variables were associated with hemoglobin loss. The total cost of preoperative blood screening for these patients was €842.16.

Likelihood of receiving perioperative transfusion in bariatric surgery is very low. All blood reserve parameters show over-reserve in these surgeries. Data obtained allowed us to remove the blood reserve test in bariatric surgery of our protocol.