In the absence of infection-specific clinical signs and symptoms, it is often difficult for the maxillofacial surgeon to decide whether leukocytosis after orthognathic surgery is part of the normal postoperative response, as suggested for a variety of non-maxillofacial surgeries, or a sign of a developing infection. The aim was to determine the trends and factors predictive of postoperative WBC (white blood cell) values after orthognathic surgery that may provide the surgeon appropriate guidance for decision making.

This retrospective cohort study included a total of 83 consecutive patients who underwent 93 orthognathic surgical cases over six years. The natural history of postoperative WBC values and incidence of leukocytosis were characterized, and their differences across potential predictor variables were then analyzed using univariate analysis and multivariate regression analysis.

On post-operative day (POD) 1, the mean post-operative WBC count reached the peak level, with an increase of 11.4 × 10⁶ cells/μL. By POD 2, it declined slightly to a level approximately two times more than the preoperative level. Over the first two post-operative days, the incidence of leukocytosis was 93.5%. Multivariate regression analyses revealed that gender, duration of surgery and pre-operative WBC count were the only significant predictors of the post-operative WBC value, whereas the pre-operative WBC count was the only significant (OR: 2.61, P < 0.05) predictor of post-operative leukocytosis.

Post-operative leukocytosis after orthognathic surgery is significantly influenced by the pre-operative WBC count, and has similar trends with a much higher incidence, compared to non-maxillofacial surgeries.