Cannulation of a resistant internal os with the malleable outer sheath of a coaxial soft embryo transfer catheter does not affect in vitro fertilization-embryo transfer outcome

OBJECTIVE: To assess the impact of cannulation of a resistant cervical os with the outer malleable sheath of a double-lumen, soft ET catheter on IVF-ET outcomes. DESIGN: Retrospective cohort study. SETTING: University-based IVF center. PATIENT(S): One hundred forty-two patients undergoing 142 ETs. INTERVENTION(S): Trial ultrasound-guided ET at all transfers, leaving the malleable outer sheath in situ when the soft inner catheter could not negotiate the internal os. MAIN OUTCOME MEASURE(S): Implantation rate and clinical pregnancy rate. RESULT(S): In 102 ETs (71.8%), the soft inner sheath easily negotiated the internal os (group 1). Forty ETs (28.2%) required cannulation of resistant internal ora with the outer sheath of the trial catheter (group 2). Implantation rates (35% vs. 32% in groups 1 and 2, respectively) and clinical pregnancy rates (50% vs. 45%) were not significantly different between groups. Blood was present on the transfer catheter after ET more frequently in group 2 than in group 1 (55% vs. 15%); however, neither the implantation rate nor the clinical pregnancy rate were affected by the presence of blood. CONCLUSION(S): Cannulation of a resistant internal os by the malleable outer sheath and blood on the transfer catheter after ET do not have an adverse effect on implantation rate or clinical pregnancy rate.