Why do they cancel surgery if you're sick? An expert's guide to patient safety

September 29, 2025 •

4 min read

Statistics from various studies show that patient unsuitability, often due to illness, is a leading cause of elective surgery cancellations. There are several critical medical reasons why do they cancel surgery if you're sick, all focused on minimizing risks and ensuring the best possible outcome for you.

Quick Summary

Elective surgery is often canceled when a patient is sick to minimize significant health risks, including complications from anesthesia, a weakened immune response, and compromised healing. This cautious approach ensures the best chance for a successful procedure and a smooth recovery, protecting the patient's well-being.

Key Points

Anesthesia Risks: Combining anesthesia with an illness, especially a respiratory one, increases the risk of breathing complications and adverse reactions during surgery.
Weakened Immune System: Your body's resources are diverted to fight illness, leaving less energy for healing and increasing the risk of postoperative infections.
Delayed Healing: A compromised immune system and general bodily stress from illness can lead to a longer, more difficult recovery period after surgery.
Protecting Others: Canceling surgery for a contagious patient prevents the spread of illness to other vulnerable patients and staff within the healthcare facility.
Emergency vs. Elective: The decision to cancel depends on the procedure's urgency; elective surgeries are more likely to be postponed, while emergency procedures may proceed despite illness.
Communicate with Your Team: It is crucial to inform your surgeon's office immediately if you fall sick before a planned operation to allow for proper risk assessment and rescheduling.

The Primary Concern: Patient Safety

When you are ill, your body is under stress, and your immune system is occupied fighting the infection. Elective surgery, while planned, is still a major stressor for the body. Adding the strain of a surgical procedure to an already compromised system significantly increases the risk of complications during and after the operation. Medical teams, including surgeons and anesthesiologists, must conduct a thorough risk assessment to ensure that the patient is in the best possible state of health to undergo the procedure safely. This is especially crucial for non-emergency or elective procedures where delaying the operation does not pose a greater threat than proceeding while unwell.

The Dangerous Mix of Anesthesia and Illness

Anesthesia is a powerful set of medications designed to make you unconscious and pain-free during surgery. However, its use becomes more complicated and risky when a patient is sick, particularly with a respiratory infection.

Increased Respiratory Risks

Compromised Breathing: Upper respiratory infections, such as a cold, flu, or sinus infection, can affect your breathing even under normal circumstances. When under general anesthesia, an anesthesiologist monitors and often controls your breathing. A pre-existing respiratory issue can make this process more difficult and increase the chances of dangerous breathing problems, like low oxygen levels, during surgery.
Airway Reactivity: A respiratory illness can increase the reactivity of your airways, leading to spasms, wheezing, or laryngospasm (a painful and dangerous spasm of the vocal cords) during or after the procedure.
Exacerbated Symptoms: A sore throat, a common side effect of intubation for general anesthesia, can be made significantly worse if you already have a throat infection. A nagging cough can also put immense strain on the body, which is a major concern if you are recovering from a procedure that involves sutures.

Weakened Immune Response and Infection Risk

Your immune system is your body's defense against infection. A surgical procedure intentionally creates a wound, making the body susceptible to infection. For your body to heal and fight off potential pathogens, a strong immune response is necessary.

Potential Complications

Increased Postoperative Infections: When you are sick, your immune system is already spread thin. Performing surgery under these conditions can increase the risk of postoperative infections, including pneumonia, wound infections, and blood clots.
Delayed Healing: The healing process demands a lot of energy and resources from the body. If your body is also fighting a viral or bacterial infection, its resources are diverted, leading to slower healing and a potentially prolonged recovery time.

Protecting the Healthcare Environment

Beyond individual patient safety, canceling surgery for a sick patient is also a measure to protect other patients and staff. Many people in a hospital or surgical center already have weakened immune systems, making them highly vulnerable to contagious illnesses like the flu or COVID-19. By postponing surgery, the medical facility prevents the spread of infection, creating a safer environment for everyone.

The Difference Between Elective and Emergency Surgery

Not all surgeries are canceled due to illness. The decision depends heavily on the type and urgency of the procedure. Here is a comparison:


Factor	Elective Surgery (Rescheduled)	Emergency Surgery (Proceeds)
Urgency	Non-life-threatening procedure with a flexible schedule.	Urgent, life-threatening situation requiring immediate intervention.
Illness Risk	High risk of complications from illness outweighs the risk of delaying the procedure.	The risk of waiting for recovery is higher than the risk of proceeding while ill.
Example	A joint replacement or cosmetic procedure is postponed due to a recent respiratory infection.	A patient with a ruptured appendix or severe trauma needs immediate surgery, even if they have a fever.
Decision	Made by the medical team based on a pre-operative assessment and risk analysis.	Made with consideration of the most immediate threat to the patient's life.

What to Do If You Get Sick Before Surgery

If you have a scheduled operation and start to feel unwell, it is crucial to communicate with your medical team as soon as possible, rather than waiting to see if you get better.

Notify Your Surgeon's Office: Call the office immediately and describe your symptoms. This allows the medical team to assess the situation and determine the safest course of action.
Be Transparent: Do not downplay your symptoms. Be honest and forthcoming about how you feel to give your medical team an accurate picture of your health status.
Discuss With the Anesthesiologist: On the day of the procedure, if you are still experiencing minor symptoms, the anesthesiologist will conduct a final assessment to decide if it is safe to proceed.
Reschedule When Advised: While inconvenient, rescheduling is always in your best interest. It ensures that you have the best possible chance for a safe and successful outcome.

For more detailed information on preoperative evaluations and preparation, you can consult authoritative medical resources like those provided by the Mayo Clinic. What is a preoperative evaluation?.

Conclusion: Prioritizing Your Health

While a surgery cancellation can be frustrating and disruptive, it is done with the utmost consideration for your safety. Medical professionals are trained to evaluate the potential risks of surgery, and an acute illness significantly alters that risk-benefit analysis. By delaying the procedure, they give your body the time it needs to recover, ensuring your immune system is strong, your respiratory system is clear, and your recovery is as smooth as possible.

Frequently Asked Questions

Yes, even a mild cold can cause a cancellation, particularly if it's accompanied by other symptoms like a cough, fever, or congestion. The decision depends on the type of surgery, the severity of the symptoms, and your overall health. Always inform your medical team, as respiratory symptoms can increase anesthesia risks.

The waiting time depends on the type of illness, its duration, your overall health, and the surgery being performed. Your surgeon or anesthesiologist will provide specific guidance, but it can range from a few weeks after a respiratory infection to longer for more serious illnesses.

You should contact your surgeon's office immediately. Do not assume your surgery will be canceled, and do not hide your symptoms. The medical team will assess your condition and determine if it's safe to proceed or if rescheduling is necessary.

A fever is a strong indicator of an active infection and is a common reason for cancellation, especially for elective surgery. It suggests that your immune system is fighting an illness, making it an unsafe time for surgery and anesthesia.

Yes, for children, medical teams are even more cautious. A child with a cold, fever, or other illness will often have their elective surgery rescheduled to prevent complications under anesthesia, especially respiratory problems.

Yes. When you are sick, your immune system is compromised and less effective. This can increase the risk of a new infection developing at the surgical site or elsewhere in your body after the procedure.

Cancellation policies vary by hospital and clinic. Some may charge a fee if you cancel at the last minute, while others are more lenient when it comes to illness. It is best to notify your surgeon's office as soon as possible to understand their specific policy.