On the basis of the evidence available in this review, no specific conclusion can be made regarding the superiority of one catheter class over another. Further adequately powered studies reporting on clinical outcomes (e.g. live birth rate) are required. Additional outcomes such as miscarriage rates and measures of discomfort need to be reported.
Flexible versus rigid intrauterine insemination catheters: a prospective, randomized, controlled study.
To prospectively compare pregnancy rates for couples undergoing IUI by a single healthcare provider with random assignment to either rigid (Tomcat; Kendall Sovereign, Mansfield, MA) or flexible (Soft Pass; Cook, Spencer, IN) catheters.
                Randomized, controlled study.
                Tertiary care infertility practice.
                One hundred infertile women enrolled from a single infertility practice who met the inclusion and exclusion criteria for IUI were enrolled. Of the 100 patients, 95 underwent ovarian stimulation before IUI: 35 with clomiphene citrate alone, 60 with clomiphene citrate combined with a single dose of gonadotropins.
                Timed IUI was performed with either rigid (Tomcat) or flexible (Cook) insemination catheters.
                Pregnancy rate per cycle.
                No differences were noted between groups for the following: age, length of infertility, day-3 FSH level, number of prior IUI cycles, total motile sperm count, days of abstinence, infertility diagnoses, insemination ratings, and stimulation protocols. No difference in pregnancy rates was observed between rigid and flexible catheter groups.
                There is no statistically significant difference between flexible and rigid catheters for IUI.