Changes in hemoglobin and hematocrit levels following orthognathic surgery of the mandible.

Red blood cell mass has been shown to recover rapidly with great decreases, as occurs in orthognathic surgery. However, blood loss during bilateral sagittal split osteotomy is considered minimal. The purpose of this study was to verify changes in hemoglobin (Hb) and hematocrit (Ht) levels following orthognathic surgery of the mandible. Data from 12 patients with a mean age of 27.5 years, from both genders, that were submitted to bilateral sagittal split osteotomy in the prognathism reduction were evaluated. No patient received blood transfusion during the procedure nor postoperatively. Procedures were performed by the same surgeon, with the use of reciprocating and sagittal saws. Levels of Hb and Ht were obtained in preoperative, one day postsurgery, and one, three and six weeks postoperatively. Statistical analyses were used to verify the difference in each group, and between periods. Patients lost a mean decrease in Hb of 2.0 g/dl, and in Ht of 5.2%. There was significant difference as to the levels of Hb (p=0.002) and Ht (p=0.010). These levels presented significant changes from immediate postoperative to six weeks for Hb, and to three weeks for Ht. It was concluded that a slow recovery of hemoglobin and hematocrit levels occurred following orthognathic surgery of the mandible.