Why does a nurse advice her patient to drink enough fluids following his spinal injury?

Urinary tract infection.

Clients in the early stage of spinal cord damage experience an atonic bladder, which is characterized by the absence of muscle tone, an enlarged capacity, no feeling of discomfort with distention, and overflow with a large residual. This leads to urinary stasis and infection. High fluid intake limits urinary stasis and infection by diluting the urine and increasing urinary output.