What is the role of a pad test in the assessment of urinary incontinence?

Updated: Jan 22, 2021
  • Author: Sandip P Vasavada, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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A pad test is a useful adjunct to the patient's history and physical examination. The pad test is an objective test that determines whether the fluid loss the patient is experiencing is in fact urine. Intravesical methylene blue, oral phenazopyridine (Pyridium), or oral Urised (methenamine, methylene blue, phenyl salicylate, benzoic acid, atropine sulfate, hyoscyamine) may be used as a coloring agent. Methylene blue and Urised turn the urine blue; phenazopyridine turns the urine orange.

Pad tests may be short term or long term. Short-term tests have the advantage of convenience and assured compliance. Long-term tests may be more representative of daily incontinence.

Short-term tests generally involve the subject drinking a known volume of liquid or undergoing retrograde filling of the bladder. A preweighed sanitary pad is applied. The individual is instructed to perform specific activities such as coughing, running in place, bending and lifting, and hand washing. The testing interval can range from 15 minutes to 2 hours. At the end of the test period, the pad is removed and weighed.

Long-term tests are conducted under normal living conditions for 24-48 hours. Each pad is preweighed and then weighed again after use by the patient at home, or, alternatively, the pad is placed in an airtight plastic bag and weighed later by the clinician.

Every 1 g increase in weight is equivalent to 1 mL of urine. The International Continence Society considers the finding of a weight change of less than 1 g during its standardized 1-hour test to be a negative result. Vaginal discharge and sweat can be other physiologic sources of pad weight gain. Testing should not be conducted during menstruation, for obvious reasons.

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