ObjectiveTo explore the postoperative effect of preoperative anemia on patients undergoing unilateral total hip arthroplasty (THA).MethodsA total of 200 patients undergoing unilateral primary THA from July to September 2018 were selected. According to the preoperative hemoglobin level and the World Health Organization definition of anemia (hemoglobin below 120 g/L for women and below 130 g/L for men), the patients were divided into the non-anemia group and the anemia group. All anemia patients were given dietary guidance and balanced diet before the operation, and no drug treatment was given. Both groups adopted accelerated rehabilitation strategy during the perioperative period, and postoperative anemia was treated according to a unified standard. The intraoperative blood loss and length of operation of the two groups were recorded. The presence of anemia on the first postoperative day, postoperative blood transfusion rate, incidence of postoperative complications (hypotension, nausea and vomiting on the first postoperative day, and infection-related unplanned readmission within 90 days after discharge), range of motion of the hip joint (hip flexion and hip abduction), and length of hospital stay were compared between the two groups.ResultsIn the 200 patients, 51 (25.50%) presented anemia before surgery and 149 did not. There were 114 cases developing mild anemia and 7 cases developing moderate anemia after surgery in the non-anemia group, with an anemia incidence of 81.21%; in the anemia group, there were 30 cases of mild anemia and 20 cases of moderate anemia, and 1 case did not have anemia after surgery. The postoperative transfusion rates of the non-anemia group and the anemia group were 2.01% and 11.76%, respectively, and the incidences of postoperative complications were 7.38% and 35.29%, respectively; the differences were statistically significant (P<0.05). However, there was no statistically significant difference in hip mobility or length of hospital stay between the two groups (P>0.05).ConclusionsQuite a few patients undergoing THA have anemia before surgery. The incidence of postoperative anemia is high due to the trauma and massive bleeding of the operation, and preoperative anemia will aggravate anemia after surgery. Preoperative anemia can increase the perioperative transfusion rate of THA patients, increase the incidence of postoperative complications, and affect the hospitalization experience of patients.