Residual embryos in failed embryo transfer.

One hundred thirteen embryo transfers (ETs) were performed in an in vitro fertilization and ET program of which residual or extruded embryos were found in 17 transfers (15%). Residual or extruded embryos are those embryos found outside the uterine cavity, either at the cervical os, on the vaginal speculum, or remaining in the catheter after an ET. Patients were divided into two groups according to the method of inspection for residual embryos. In group I, microscopic visualization of the transfer catheter alone revealed that 9 of the 67 transfers (13.4%) had 17 residual embryos either at the catheter tip or adherent to mucus on the side of the catheter. In group II inspection of the catheter and cervical wash revealed that 8 of 46 ETs (17.4%) had 15 residual embryos that failed to be transferred during the initial attempt. Six of these 15 (40%) were found in the cervical wash medium. Thus, failure of the proper placement of embryos at the time of transfer may occur frequently. Evaluation of only the transfer catheter may result in a significant underestimation of the problem.