The causes and pathological changes of bladder contraction are that the tubercle bacilli often repeatedly invade the bladder from renal tuberculosis, causing severe tuberculous cystitis. In the mucosal and muscular layer of the bladder, congestion, edema, tuberculous nodules, tuberculous ulcers, and tuberculous granulation tissue are produced, with a large number of lymphocytes infiltrating and fibrous tissue formation. Finally, bladder contraction occurs. After bladder contraction, the bladder wall loses its normal elasticity, and the capacity is significantly reduced. It is generally believed that the capacity of the contracted bladder is below 50ml. In severe cases, the bladder can shrink to several milliliters of capacity. Due to the repeated infection of the bladder by the tubercle bacilli, the pathological changes in the bladder are an acute and chronic, inflammation and fibrosis, a process of repeated interaction.