These comments are only about loss of control of bowels and bladder for play, not anything to do with actual medical conditions.
It is easily possible to do stuff that will make someone absolutely incapable of controlling their pee and/or poo in any way.
Making someone lose pee control is simple and works for both men and women.... a urinary catheter. This can be a simple in-and-out to completely empty the person's bladder or a Foley which can stay in for longer periods of time. The in-and-out most always completely empties a person's bladder within a few minutes. Once the catheter is in a person, they are going to pee until empty. There is no amount of muscle straining or anything else that's going to stop the flow, except if the catheter is expelled, which can happen quite easily if it's not held in place.
For longer term use, a Foley catheter is used. These have a little balloon near the tip and once the catheter is in somebody, the balloon is filled with a few ml of sterile water. One a Foley is properly in and the balloon is inflated, all control of peeing is lost until the catheter is removed. The person will dribble pee through the catheter 24/7. Period.
Making someone lose poo control is pretty much the same. Essentially, a tube goes into the person's anus that prevents the muscles from closing the opening. There are a variety of anal rings and hollow butt plugs that do this. Some have a bulge on the inside to ensure the plug cannot be pood out and some have a harness or straps to prevent their expulsion. Since the person can no longer close their anal opening, the poo just comes out. A strong dose of a stool softener and/or laxative hastens the process.
There are also purpose-made products for this purpose which are similar to a closed system colon hydrotherapy session. A rigid tube is inserted, and a large volume enema is given with the outflow tube clamped, and then the clamp released. Not pooing is impossible.
A combination of a Foley catheter and a disposable closed colon cleansing system completely removes a person's control of their most intimate body functions.