What defines straight catheters?

Straight catheters are specifically designed for single-use procedures where the catheter is inserted into the bladder to drain urine and is then immediately removed after the drainage is complete. This approach allows for temporary bladder emptying without the need for ongoing bladder management or the risks associated with indwelling catheters that stay in place for extended periods. The primary function is effective drainage for a short time, making this option that correctly defines straight catheters.

The other answer choices relate to different types of catheters. Some catheters are designed to be indwelling, meaning they remain in place for longer durations and may present risks such as infection. Continuous drainage mechanisms are associated with specific types of catheters that allow for ongoing urine collection, not temporary uses like straight catheters. Additionally, the idea of catheters that are adjustable in size does not pertain to straight catheters, as this characteristic is not typical or necessary for their intended use.