Urine remaining in the bladder after urination. In acute retention, this arises suddenly; in the chronic condition, a little urine remains in the bladder each time urine is passed. Urine retention is usually caused by constriction either at the neck of the bladder or in the urethra, as a result of sclerosis of the neck of the bladder, swollen bladder, bladder stones, a stone in the urethra or a narrowing of the urethra. In middle-aged men, the cause is frequently an enlarged prostate. One reason why retention can occur in women is pressure on the urethra as a result of prolapse of the bladder during pregnancy or in swelling of the uterus. Spinal cord disorders can also cause urine retention. Acute retention with stretching of the bladder is accompanied by pain, but in chronic retention this is usually not the case. Cystitis can easily occur because some urine always remains in the bladder. Treatment of urine retention is generally aimed at eliminating the cause. In the first instance, the bladder is often emptied by a catheter. If this is not possible, the bladder can be pierced above the pubis in order to draw off urine.