Originally posted here by Kathryn Hess, MMS, PA-C, at Texas Children’s Hospital

If your child is undergoing a surgical procedure, there can be a lot of stress and uncertainty surrounding the process. Your level of worry may even increase if your child then develops a fever after the surgical procedure. Although there are many causes of postoperative fever, below are four common questions parents have about postoperative fever.

What is technically considered a fever?

Fever is defined as a temperature greater than 100.4oF. After undergoing any surgical procedure, developing a fever during the postoperative period is common. There are numerous reasons why someone may become feverish after surgery.

How does a fever occur?

Surgical procedures cause trauma to cells and tissues of the body. When this trauma occurs, the damaged cells release little molecules called cytokines. These cytokines help regulate immunity, and one of the ways they do this is by triggering the release of a molecule called prostaglandins. The prostaglandins then signals the brain to increase the body’s temperature, which results in a fever. Hence, the most common cause of a mild temperature after a surgical procedure is the manipulation of tissues and cells during the procedure

What may be causing my child’s postoperative fever?

A common acronym your clinician may use to decipher the potential cause of postoperative fever are the “5 Ws.” These stand for “wind, water, wound, walking and wonder drugs.”

  • Wind: Reminds the medical team to check for partial collapse of the lung, also known as atelectasis. A chest X-ray may be used to determine if your child is experiencing atelectasis.
  • Water: Represents the potential for urinary tract infections, which is common, especially if a urinary catheter was used during and post-surgery.
  • Wound: Represents a possible surgical site infection. Surgical site infections are a major risk with any surgical procedure. Your child’s medical team will instruct you on how to care for the surgical site.
  • Walking: Reminds clinicians to check for blood clots in the legs, such as deep vein thrombosis.
  • Wonder drugs: Represents a potential side effects as a result of the specific medications your child may be taking. Certain medications have a higher risk of causing fever. For example, penicillin and sulfonamide medications are notorious for causing fevers.

Does the timing of the fever matter?

Yes, it absolutely does. While the “5 Ws” are a quick way to determine the potential cause of postoperative fever, your clinician will also consider the time frame in which the fever occurs. If a fever occurs within the first 48 hours after surgery, the cause is more likely non-infectious; it is likely the body’s response to damaged tissue. Fevers that occur more than 48 hours after surgery have a higher likelihood of being caused by infection from the surgical site. To simplify the timeframe of postoperative fevers, timing is categorized into “immediate, acute, subacute and delay.”

  • Immediate – occurring within the first few hours after surgery: Possible causes of immediate fevers may include reaction to blood products, adverse reactions to medications, presence of inflammation or trauma prior to and during surgery.
  • Acute – occurring within the first week of surgery: Possible causes of acute fevers may include infectious causes, such as urinary tract infections, pneumonia, and intravascular (IV) catheter infections. While surgical site infections are possible within this acute period, they are more likely to occur within the subacute time frame, or more than one week after surgery.
  • Subacute – occurring around 1-4 weeks post-surgery: Other causes of fever in the subacute period may be central line catheter infections, blood clots (DVT or pulmonary embolism), or drug reactions.
  • Delayed – occurring more than 1 month after surgery: Causes of delayed fevers are most commonly due to viral infections or delayed cellulitis.

Other possible causes of postoperative fever

Other considerations such as patient age, location of surgery, invasiveness of surgery, prior tissue inflammation and duration of surgery can also help determine a potential cause for delayed fever. The degree of tissue damage can depend on the type of surgery performed, as well as on the duration of surgery. For example, someone undergoing a laparoscopic appendectomy is at reduced risk of spiking a fever compared to someone who may have undergone open-heart surgery.

If your child develops any fever in the postoperative period, you should notify the surgeon immediately. Look for signs that may indicate an infection, such as fever, redness around the surgical site, discharge coming from the surgical site, warmth around the surgical site, pain with urination, pain with walking, difficulty breathing, or rash, and be sure to report any abnormalities to your child’s clinical team.