Systematic Review and Meta-analysis Finds Little Evidence on Benefits of Cervical Mucus Removal Prior to Embryo Transfer in ART Cycles

Pregnancy rates during IVF/ICSI cycles may be adversely impacted even by small variations in embryo transfer methods. Although some studies have evaluated the impact of removal of cervical discharge on ART outcomes, there is a lack of consensus on the embryo transfer outcomes. A recent systematic review and meta-analysis, published in Fertility and Sterility, did not find any significant proof regarding the beneficial effects of cervical mucus removal before embryo transfer in improving the IVF/ICSI cycle outcomes.

Laurentiu Craciunas, Clinical Fellow in Obstetrics and Gynaecology, St. Mary’s Hospital, Central Manchester University Hospitals Foundation Trust, United Kingdom, and colleagues analyzed eight randomized clinical trials to determine the effectiveness of removing cervical mucus prior to embryo transfer in 1715 patients undergoing IVF/ICSI cycles. The researchers noted that there are only moderate-to-low quality trials available, which fail to provide any evidence on the overall usefulness of cervical mucus removal prior to embryo transfer. The meta-analysis further reported significant heterogeneity in the trials and found no statistically significant variation in the rates of implantation, pregnancy, and live birth. Considering the statistical heterogeneity, clinical diversity, and bias risk, the scientists emphasized the need for more randomized controlled trials in multiple centers to arrive at a consensus on the probable beneficial effects of cervical mucus removal.

In order to investigate if cervical mucus aspiration resulted in better clinical outcomes, Eskandar et al conducted a prospective controlled study (Reproductive Biomedicine Online, 2007) on 286 women undergoing ART. The patients were divided into two groups depending on whether they underwent cervical mucus removal (group A) or not (group B). Both the groups had similar features with respect to the cause of infertility, demographics, ovarian stimulation characteristics, and number of embryos transferred. The results showed that group A, in whom cervical mucus aspiration was performed, had higher clinical pregnancy rate (OR = 2.18; 95% CI = 1.32-3.58) than group B. However, the performance of embryo transfer was easier in those subjects who did not undergo cervical mucus aspiration (OR=3.00; 95% CI=1.05-8.55).

As per another prospective, single blind, randomized controlled study by Visschers et al (Reproductive Biomedicine Online, 2007), cervical mucus removal before embryo transfer may not significantly improve live birth rate, but could not exclude a small beneficial impact. The study involved 317 couples who underwent 428 IVF/ICSI cycles, wherein the findings of three cycles were not known. The treatment group in whom cervical mucus was removed had live birth rate of 24% (52/220) as opposed to 21% (42/205) in the controls (risk difference=3%; 95% CI=5- 11%).

By covering the embryo transfer catheter during its passage to the cervical canal, cervical mucus may potentially interfere with the proper placement of the embryo in the uterine cavity. Moreover, during the withdrawal of the catheter, the transferred embryos may stick to the cervical mucus around the catheter. Thus, the embryos may be dislodged from the original site of deposition. Some studies have also indicated the probable interference of the mucus during implantation, when it reaches the uterine cavity. One of the advantages of mucus removal and cervical cleaning is that it decreases the risk of bacterial contamination of the endometrial cavity and catheter. Considering the several advantages associated with the procedure, Eskandar et al (Reproductive Biomedicine Online, 2007) recommended the need to perform cervical aspiration before embryo transfer in all patients undergoing embryo transfer via the cervical route in routine clinical practice.

On the contrary, there are trials which indicate some of the negative effects of the procedure such as increased time required for the additional procedure in a busy IVF center, with no improvement in the clinical outcomes. By eliminating the naturally lubricant mucus, this procedure may enhance the number of difficult transfers. As the results on the potential effectiveness of cervical mucus aspiration seem inconsistent, further large randomized studies are needed to validate the findings, and investigate the association between the presence of retained embryos and the difficult embryo transfer procedure.

References

  • Craciunas L, Tsampras N, Fitzgerald C. Cervical mucus removal before embryo transfer in women undergoing in vitro fertilization/intracytoplasmic sperm injection: a systematic review and meta-analysis of randomized controlled trials. Fertil Steril. 2014 May;101(5):1302-1307.e6.
  • Eskandar MA, Abou-Setta AM, El-Amin M, Almushait MA, Sobande AA. Removal of cervical mucus prior to embryo transfer improves pregnancy rates in women undergoing assisted reproduction. Reprod Biomed Online. 2007 Mar;14(3):308-13.
  • Visschers BA, Bots RS, Peeters MF, Mol BW, van Dessel HJ. Removal of cervical mucus: effect on pregnancy rates in IVF/ICSI. Reprod Biomed Online. 2007 Sep;15(3):310-5.

Comments are closed.


Stay Updated via our Twitter Alerts!

Follow IVF NEWS.Direct! on Twitter

Categories

Archives