Which solution is contraindicated on a sterile field for an endoscopic case using electrosurgical instruments?

In the context of an endoscopic case using electrosurgical instruments, the use of normal saline is contraindicated on a sterile field due to its electrical conductivity properties. When an electrosurgical device is activated, the current can flow through solutions that are conductive. Normal saline is an ionic solution, meaning it allows electrical current to pass through it. If it comes into contact with the electrosurgical instruments, it can lead to unintended current flow, which may result in burns, tissue damage, or even affect the functionality of the device.

On the other hand, solutions like sterile water and chlorhexidine are not conductive and can be used safely around electrosurgical instruments. Betadine, while it is an antiseptic, is also typically avoided on sterile fields but for different reasons, such as potential reactions or staining but does not present the same risks regarding conductivity. Thus, the safety of using non-conductive solutions is crucial in maintaining a secure and effective sterile environment during endoscopic procedures involving electrosurgical tools.