A stoma bag works by being placed over the stoma, so that waste products are collected as they’re expelled. The bag collects urine or faeces, depending on the type of stoma, and can either be drainable via an opening at the bottom of the bag, or closed and removed as a whole unit when full.
Both drainable and closed styles are available as one- or two-piece bags; one-piece bags have an adhesive pad attached to them which sticks to the skin and is removed as a whole unit when the bag is full, whereas two-piece bags have the adhesive pad separately.
This adhesive pad (called a flange) can remain in place for a few days as two-piece bags are removed and replaced. The advantage of the two-piece system is that the skin remains undisturbed as bags are emptied and changed, reducing the risk of aggravated and sore skin.