Bethanechol is used to treat urinary retention by stimulating detrusor muscle contractions.

• A. Increasing urine production
• B. Relaxing the detrusor muscle
• C. Stimulating bladder contractions
• D. Inhibiting bladder contractions

Answer: (C)

This item tests how a cholinergic agonist helps relieve urinary retention by activating the bladder’s muscle. Bethanechol is a muscarinic (parasympathomimetic) agent that stimulates receptors in the bladder, especially the detrusor muscle. When the detrusor contracts, the bladder empties more readily, reducing retention. The other ideas don’t fit: increasing urine production comes from effects on the kidneys or diuretics, not detrusor contraction; relaxing the detrusor would make it harder to void; and inhibiting bladder contractions would prevent voiding. So the action that best explains its use is stimulating bladder contractions.