 The various ways these tests are performed have also been evaluated. For example, there was no statistical difference in outcomes of a CST; whether completed supine or standing and independent of bladder volume. In regards to the pyridium pad tests, several studies have compared a 1 hour to 24 hour pyridium pad test with varying results of efficacy. Furthermore, in a study done when comparing pad weight and color, even asymptomatic women had positive pyridium pad tests suggesting this test is less specific in identifying SUI. A secondary analysis of the looked at how different reduction methods effect the predictability of post-operative SUI on UDS. Reduction of pelvic organ prolapse with a speculum was the most sensitive in identifying post-operative SUI at 53. However, there is a paucity of evidence as to which pre-operative test is best in identifying SUI in patients with pelvic organ prolapse. 