Constipation and a frequent or urgent need to urinate may occur along
with low back pain. They usually are not symptoms of another problem.
However, the involuntary passing of urine or stool—or an inability to
urinate at all—may result from damage to the nerves that control the function
of the bladder, bowel, and sex organs. This may be caused by:
Loss of bowel or bladder control is a medical emergency, and you
should see a doctor right away.