What is a wound infection

A wound infection is one that develops at the site of surgical incision (or cut) when you had your surgery. It can occur a few days or up to a few weeks after your operation. Many wounds normally appear slightly discoloured after surgery and this usually disappears after a few days. An infected wound however may be discoloured, hot, swollen, painful and leak pus (white, yellow, green or coffee coloured thick cloudy fluid). If you have an infected wound you might also have a high temperature of above 380C or feel feverish.

With a heart bypass operation you may have an incision wound on your legs or arms (where a vein graft was taken) as well as on your chest. It is possible for any of these wounds to become infected.

Causes

Most surgical wounds heal quickly without any infection. However, bacteria can enter your wound during your surgery or after your surgery before your wound has healed. If these bacteria multiply, they can cause a wound infection. These bacteria may come from your own body, usually the surface of your skin, or they may come from the air in the operating theatre, equipment or other people. If the edges of your wound do not come together after surgery, or if they separate again, it is possible for bacteria to enter your wound through any small gaps.

Types

Wound infections are usually described by the depth or area that they affect. If only the top skin layers are affected, it is called a ‘superficial infection’. Sometimes, the area under the skin along the incision also becomes infected and this is called a ‘deep infection’.  Superficial or deep infections can involve the whole length of the wound or only parts (or sections) of it.

Less commonly, severe infections can develop after heart surgery which affect the heart or bone, these are called ‘organ/space infections’. For instance, the valve inside the heart can become infected (infective endocarditis) or the lining that covers the heart can become inflamed and infected (e.g. pericarditis). These types of infection may not be visible to the naked eye so symptoms of infection, such as high fever or general unwellness, should be discussed with your doctor. Infections can also develop in the chest bone (mediastinitis) or affect leg bone (osteomyelitis) if the area where a vein graft (blood vessel) was taken from becomes badly infected.

Rates

Published research rates of wound infections after heart surgery vary from 1% to 10%.  These rates can be affected by different infection prevention practices used at each hospital and whether some patients are more likely to develop infections. The rates also vary depending on which method of wound infection monitoring is used (hospitals can use a variety of different ways to measure wounds).