Contamination of embryo transfer catheter and treatment outcome in in vitro fertilization

Purpose: The effect of embryo transfer (ET) catheter contamination with mucus and/or blood on treatment outcome in an in vitro fertilization (IVF) program was evaluated. Methods: One thousand four ET procedures in 877 patients having conventional IVF in the long (1189 cycle) and short (15 cycles) protocol were analyzed to determine the impact of catheter contamination on the incidence of retained embryos and the clinical pregnancy rate, Results: Catheter contamination with mucus and/or blood is a feature of difficult ET. Embryos were significantly more likely to be retained when the transfer catheter was contaminated with mucus (17.8 versus 3.3%) or blood (12 versus 3.3%). When the catheter was contaminated and an embryo(s) was retained and immediately retransferred, the pregnancy rate was not compromised. The pregnancy rate was significantly reduced when the ET catheter was contaminated with blood (15.5 versus 27.1%; P = 0.002), but no embryo was retained in the catheter set Conclusions: Catheter contamination compromises the treatment outcome in IVF only when there is no associated retained embryo(s). As increased vigilance in searching for extruded embryos may not be practical, we suggest that cervical mucus should be routinely aspirated and ET performed as atraumatically as possible.