Mock embryo transfer does not affect uterine contractility.

OBJECTIVE: To assess the degree of utero-stimulation induced by transcervical introduction of a catheter as in mock ET. DESIGN: Prospective study. SETTING: Reproductive medicine unit. PATIENT(S): Eighty volunteers undergoing mild ovarian stimulation and IUI. INTERVENTION(S): Just before IUI, women had uterine contraction (UC) frequency assessed with 2-minute sagittal ultrasound scans of the uterus (precatheter measurement). Thereafter, one of three types of catheters, each with a different stiffness level (low, n = 25; medium, n = 30; or high, n = 25) was introduced into the cervix up to the inner cervical os, then immediately withdrawn, and the UC frequency reassessed (postcatheter measurement). MAIN OUTCOME MEASURE(S): Percentage change in UC frequency. RESULT(S): Median (range) UC frequency was not significantly different at pre- and postcatheter measurements: 2.0 (0.0-4.5) UC per minute and 2.2 (0.0-5.5) UC per minute. In addition, the stiffness of the catheter (low, medium, or high) did not influence the UC frequency, with median (range) percentage of change from pre- to postcatheter measurement at 0 (-100% to +75%), 0 (-100% to +100%), and 0 (-40% to +100%), respectively. CONCLUSION(S): The introduction of a catheter up to the inner cervical os, as usually performed in mock ET, does not stimulate uterine contraction frequency, irrespective of catheter stiffness.