Intermittent self-catheterization (ISC) may be needed, because your bladder does not empty completely or it does not empty at all. There are many causes for this problem in some cases called neurogenic bladder: stroke, spinal cord injury, diabetes, spina bifida, and obstruction to the outflow of urine are the most common reasons. Sometimes after an operation on the colon such as a colostomy, the bladder does not empty well and you may need to self catheterize for some time until the bladder begins to function normally again. ISC may be required for several days, weeks, months or indefinitely. This procedure is often taught to patients by Occupational Therapists (OT) or Rehabilitation Nurses (RN).