What is Postoperative Fever?
Postoperative fever means a patient has temperatures exceeding 38 C (or over 100.4 F) on two days in a row after surgery, or greater than 39 C (or over 102.2 F) on any day after surgery. Understanding the possible diagnoses for this condition, and applying a step-by-step approach, can be very helpful in pinpointing the exact cause, and starting the right treatment.
It’s important to remember that a fever can be a sign of sepsis, which is a serious infection that spreads throughout the body. Sepsis needs to be quickly spotted and treated correctly to lessen the chances of severe health risks in such cases.
What Causes Postoperative Fever?
The cause of a medical issue can often be influenced by the timing.
For example, people with certain conditions that weaken the immune system might not show typical signs of an infection like inflammation or fever, despite having a serious infection.
When a patient has a fever, doctors need to consider several possible causes. These can be both infectious, from germs like bacteria present in the hospital or at the surgical site, and non-infectious. Non-infectious causes range from blood clots in the veins (deep vein thrombosis), blockages of the arteries in lungs (pulmonary embolus), heart attacks (myocardial infarction), reactions to drugs or blood transfusion, to hormone-related conditions such as adrenal insufficiency, which is when your body doesn’t produce enough hormones, or thyroid storm, which is a life-threatening health condition associated with untreated or undertreated thyroid disease.
A fever that occurs a long time after surgery is more likely to be caused by an infection. It’s also important to note that a patient might have more than one thing causing their fever at the same time, so it’s possible for both infectious and non-infectious causes to be present.
Risk Factors and Frequency for Postoperative Fever
Postoperative fever, or a fever that happens after surgery, is a common occurrence. The exact numbers are not clear, but it happens in a high percentage of patients. Depending on the type of operation, between 20% to 90% of patients may develop a fever in the early days following surgery, usually on the first or second day. Most of these cases are tied to harmless causes.
This type of fever can happen after any kind of surgery, no matter what type of anesthesia was used. It also occurs in children and in both males and females. While it can occur after smaller surgeries, it’s quite rare and depends on the specific procedure. However, surgeries involving the abdomen and chest tend to result in the highest amount of post-surgery fevers.
Signs and Symptoms of Postoperative Fever
Fever is a common symptom that may occur after surgery, and depending on when it appears, it could be an indication of various underlying issues. Reasons for fever can be categorized based on when it’s observed: Immediately after surgery, Within the first week following surgery, Between 1 to 4 weeks after surgery, and More than 4 weeks after surgery.
Immediately after surgery or within the first day, fever can be a sign of:
- Malignant hyperthermia: This is usually due to exposure to certain anesthetics or muscle relaxants. Symptoms include a high fever and a family history of problems with anesthesia.
- Bacteremia: This can occur when bacteria enter the bloodstream and cause a high fever. This often happens soon after procedures such as urinary tract instrumentation if urine is infected.
- Gas gangrene: This infection can cause a high fever after gut-related surgery. It’s treated with surgery and antibiotics.
- Febrile non-hemolytic transfusion reaction: This can cause fever, chills, and discomfort 1 to 6 hours after surgery. It’s managed by stopping the transfusion and administering antipyretics (fever-reducing drugs).
Within the first week following surgery (Day 1 to 7), fever could be caused by:
- Typical response to surgery during the first 48 hours.
- Pneumonia due to unresolved atelectasis (collapsed lung) on Day 3, diagnosed with a chest x-ray, sputum culture, and treated with antibiotics.
- Urinary tract infection, diagnosed with analysis and culture of urine, and treated with antibiotics.
- Thrombophlebitis (blood clot in a vein) on Day 5, diagnosed with ultrasound, and treated with heparin.
- Pulmonary embolism (blood clot in the lungs) or wound infection on Day 7, diagnosed with an angiogram, and treated with heparin or antibiotics and drainage, respectively.
Fever that occurs between weeks 1 and 4, also known as subacute fever, could be due to:
- Deeper infections in the pelvic or abdomen, diagnosed with a rectal exam or CT scan, and treated with surgery or radiologically guided percutaneous drainage.
- Drug reactions, diagnosed by a rash and peripheral eosinophilia (increase in a specific type of white blood cells).
More than 4 weeks after surgery, delayed fever, it could be due to:
- Skin and soft tissue infections (SSTI)
- Viral infections
However, keep in mind that other causes that are not time-based may still be possible. They may have different physical manifestations and are dependent on the type of surgery performed.
Testing for Postoperative Fever
Here is a simplified explanation of the crucial steps doctors follow in the early stages of medical examination:
The first step in any medical evaluation is to judge a patient’s general appearance, along with their Glasgow Coma Scale (an assessment tool that quantifies the patient’s level of consciousness) and vital signs (like heart rate, breathing rate, body temperature, and blood pressure).
The patient’s medical notes are thoroughly examined. These would include details such as the kind of procedure they underwent, when the procedure was done, any complications that occurred during the procedure, their medical history, and notes from the last ward rounds.
The intake and output of the patient is also checked. This involves understanding what the patient is eating and drinking and keeping a close check on their bowel movements. If the patient exhibits a particular type of loose, watery stool (Type 7), it may indicate that they have an infection called Clostridium difficile enterocolitis.
The doctor will look at your current treatment plan, like whether you are on antibiotics, or if you are being given medicine to prevent blood clots forming in your veins.
A system-based assessment is also carried out. This is another detailed examination, focusing on different systems of your body like lungs, heart, stomach, and urinary tract.
Certain parts of the patient’s body are closely examined for signs of infection. These could be the skin for bedsores or cellulitis, or around areas where an IV might have been inserted.
For patients with low blood pressure, a venous blood gas test may be done to measure serum lactate. This aids in administering the right amount of fluids to the patient. Increased heart rate might require an Electrocardiogram (ECG), a test to examine the heart’s electrical activity and rule out heart attack.
Certain patients also have their oxygen levels and blood sugar monitored. In carbon dioxide retaining patients, for instance, those with Chronic Obstructive Pulmonary Disease (COPD), the doctor tries to maintain an oxygen saturation of between 89% to 92%. Increased blood sugar levels also might suggest a serious infection called sepsis. a urinalysis, a test to measure various components of the urine might also be done to rule out urinary tract infection.
Blood tests include measuring white blood cell count, and C-reactive protein levels (inflammatory markers) among others. If these are increasing, it may point towards sepsis. Doctors also measure your hemoglobin level, which is a protein that helps carry oxygen throughout your body. They will check your liver and kidney function, the clotting ability of your blood, and your electrolyte levels.
Doctors might also do a culture test, which involves growing bacteria or other microorganisms to check for infection. They will take samples from your blood, urine, wounds, and potentially sputum (phlegm coughed up from the lungs) for the test.
Medical imaging procedures like a chest X-ray or abdominal ultrasound/CT scan might be done to check for the cause of your symptoms. For instance, a chest X-ray might be done to confirm or rule out pneumonia, while the abdominal imaging can check for infection or inflammation in your abdominal organs. A Doppler ultrasound scan of your legs may be done to rule out blood clots in your deep veins.
Treatment Options for Postoperative Fever
If you’re being treated for a condition that might require hospital care, you may receive treatments like oxygen to help you breathe, maintaining your body’s fluid balance to support your system, fluids directly into your veins to hydrate you more efficiently, and a urinary catheter to handle urine output if necessary. You might also be given antibiotics to fight off any infections.
You may also be given medicine for pain relief (analgesics), medicine to prevent vomiting (antiemetics), and might be advised to do incentive spirometry, which is a simple breathing exercise that can help to keep your lungs healthy.
Additionally, you’ll be given preventive treatments to stop blood clots from forming in your veins (venous thromboembolism), which may involve medication like low molecular weight heparin and the usage of special compression stockings to promote blood flow in the legs.
As part of the treatment plan, your healthcare providers will regularly update senior health professionals on your progress. They might also seek further advice from specialist doctors in infectious diseases to make sure that your treatment is as effective as possible.
What else can Postoperative Fever be?
Just like we talked about before, what might be causing the fever can depend on when it started, along with some other factors. Here are some of the major conditions that doctors could consider:
- Pneumonia
- Pulmonary embolus (blockage in a lung artery due to a blood clot)
- Wound infection
- Urinary tract infection
- Transfusion reaction (negative reaction to a blood transfusion)
- Sinusitis (inflammation or swelling of the tissue lining the sinuses)
What to expect with Postoperative Fever
In the majority of cases, a fever after surgery is harmless and goes away on its own. Patients with a condition where a blood clot travels to the lungs (pulmonary embolism) or a condition where a blood clot forms in a deep vein (deep vein thrombosis) often experience a mild fever which usually gets better within a few days of starting treatment.
However, the outlook isn’t as positive for patients who experience a leakage at the surgical joining of two sections of the intestines (anastomotic leaks) or a blockage of the intestines (bowel obstruction). These complications can lead to more serious issues, meaning the patient’s recovery might be more difficult and take longer.
Possible Complications When Diagnosed with Postoperative Fever
Not recognizing the cause of a fever or how serious it is can result in a person developing conditions such as SIRS (Systemic Inflammatory Response Syndrome), sepsis, severe sepsis, or septic shock. This could potentially lead to extended hospital stays and even a heightened risk of death.
Our List of Possible Consequences:
- SIRS (Systemic Inflammatory Response Syndrome)
- Sepsis
- Severe sepsis
- Septic shock
- Prolonged hospital stays
- Increased risk of death
Preventing Postoperative Fever
Patients who have been under general anesthesia – a state of controlled, temporary loss of sensation or consciousness – are usually encouraged to use a breathing exercise tool known as ‘incentive spirometry’. This device helps them breathe deeply to keep their lungs fully inflated and prevent the collapse of tiny air passages in the lungs, a condition known as ‘atelectasis’. Additionally, it’s essential for patients who’ve had surgery to move about as soon as it’s safe to do so. Getting up and moving around early in the recovery stage can help speed up the healing process.
