During an operation, certain sterile ‘zones’ exist in the operating theatre. These are usually centred around the operating table, and are easy to identify. For example, all the green or blue drapes are sterile. However, the exact outer borders of sterile zones are often surprisingly ill–defined (see ‘where to put your hands’, p. 42).

Most operating lights have a handle for the surgeon to adjust them; they are therefore provided with sterile over–handles, which may be either disposable plastic or re–usable metal or plastic. Some of them are screwed into place, while others (especially the disposable plastic type) are simply pushed firmly into place.

Unless you are scrubbed, gowned and gloved, do not enter the ‘sterile zone’. For example, do not walk between two sterile areas (such as between the scrub nurse's trolley and the draped patient), and do not touch the drapes. If you accidentally breach the sterile field, it is essential that you admit your mistake. For example, if your gloved finger accidentally touches something unsterile when you are scrubbed, you must immediately stop using that hand in the sterile field (unless removing the hand will cause a problem), and request a new glove from the scrub nurse, as soon as the opportunity arises. No–one should think badly of you for doing this; on the contrary, they will probably be pleased with your honesty and respect for the sterile field.

Another common way that the sterile field is accidentally breached, especially if you are tall, is by brushing your head (or hat) against the sterile light handle. If only your hat touches the handle, you may not feel it.