From the Research
Postoperative leukocytosis typically starts within hours after surgery, usually peaking at 24 to 48 hours following the procedure. This increase in white blood cell count is a normal physiological response to surgical trauma and represents the body's inflammatory reaction to tissue injury 1. The leukocytosis is primarily characterized by an elevation in neutrophils, which are the first responders to tissue damage. This response is mediated by stress hormones like cortisol and catecholamines released during surgery, as well as inflammatory cytokines produced at the surgical site.
Some studies have investigated the timing and characteristics of postoperative leukocytosis, including a 2011 study published in Clinical Orthopaedics and Related Research, which found that the average postoperative white blood cell count increased to approximately 3 × 10(6) cells/μL over the first 2 postoperative days and then declined to a level slightly higher than the preoperative level by Postoperative Day 4 1. However, the most recent and highest quality study on this topic is not available among the provided references, but based on the available evidence, it is clear that postoperative leukocytosis is a common and generally benign response to surgical trauma.
In uncomplicated cases, the white blood cell count gradually returns to normal within 4 to 5 days after surgery. Persistent or worsening leukocytosis beyond this timeframe, especially when accompanied by fever or other concerning symptoms, may indicate a postoperative complication such as infection and warrants further evaluation. The magnitude of leukocytosis generally correlates with the extent of surgical trauma, with more invasive procedures typically causing higher white blood cell elevations 2.
It's worth noting that some studies have found that preoperative asymptomatic leukocytosis may be associated with adverse postoperative outcomes, including increased risk of medical complications and infection-related postoperative complications 3. However, this is not directly relevant to the question of when postoperative leukocytosis typically starts.
Overall, the key point is that postoperative leukocytosis is a normal response to surgical trauma, and its timing and characteristics can vary depending on the individual and the type of surgery.