An Underpad is a disposable pad that is put down on many medical examining tables, hospital beds and other areas where patients either lie or sit. Chux is the medical term for the same product. Regardless of the name used, this product helps to protect the immediate area from leakage and bodily fluids while adding with a bit of padding for patient comfort.

Chux are usually blue and white and feature a thick, soft, absorbent batting backed by a thin layer of waterproof material. The soft layer absorbs liquid, blood and other bodily fluids while the waterproof backing insures the liquid won't seep through to whatever lies below. Different sized pads are available, some small enough to fit on a chair seat while others are large enough to cover a bed. Some even can absorb up to 2.5 cups of liquid before becoming fully saturated.

A super-absorbent version of the chux pad is also on the market. Some have the capacity to absorb more than eight cups of liquid. The super absorbent chux are usually only available in more compact sizes, with the largest being around three feet square.

A similar pad is also available in a reusable version. Instead of disposing of the pad when it becomes soiled, it can be thrown in the washing machine for re-use. The reusable option is a viable option for those who are bedridden or have frequent urinary accidents, but not ideal for emergency use.
In the home incontinence setting, underpads or chux are best used for providing overnight protection from symptoms of incontinence. Generally placed on top of the bed, the pads are meant to give individuals maximum comfort while sleeping.