Removal of cervical mucus: effect on pregnancy rates in IVF/ICSI

Cervical mucus may cover the embryo transfer catheter during passage of the cervical canal, interfering with the correct placement of the embryo(s) into the uterine cavity. The effect of removal of cervical mucus prior to embryo transfer in IVF/ intracytoplasmic sperm injection (ICSI) on live birth rate was studied. The study was set up as a single blind randomized controlled trial. Couples undergoing IVF/ICSI were randomly allocated to either removal of cervical mucus prior to embryo transfer, or a mock procedure. Randomization was done with stratification for age, cycle number and method of treatment. Primary outcome was live birth rate. A total of 317 couples were included and underwent 428 cycles, of which the outcome of 3 cycles was unknown. Baseline characteristics of both groups were comparable. Live birth occurred in 52 of 220 (24%) cycles in the treatment group and 42 of 205 (21%) cycles in the control group (risk difference 3%, 95% confidence interval-5- 11%). It is unlikely that removal of cervical mucus prior to embryo transfer has a significant effect on live birth rate. A small effect, however, cannot be excluded.