Newswise — Couples who have difficulty conceiving and turn to in vitro fertilization for assistance may increase their chances of pregnancy with the use of ultrasound rather than the traditional method, a new review has found.
The systematic review evaluated two techniques used to transfer an embryo into a woman's uterus after fertilization — ultrasound guidance and "clinical touch" — and concluded that ultrasound appears to improve pregnancy rates.
"The results did not surprise us," said lead author Julie Brown, M.D., of the University of Auckland in New Zealand. "We would intuitively expect a better outcome with respect to pregnancy rates with ultrasound-guided transfer over a 'blind' procedure "¦ and it was nice to have this proven in our meta-analysis."
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.
According to the reviewers, about 80 percent of women who undergo in vitro fertilization will reach the embryo transfer stage with good-quality embryos, but "only a small proportion will then go on to achieve a clinical pregnancy and fewer will achieve a live birth."
It is estimated that up to 85 percent of replaced embryos fail to implant due to a few factors: poor embryo quality, lack of uterine receptivity or the transfer technique itself.
In the clinical touch transfer technique, the clinician uses a catheter to place the embryos into the uterus. It's considered a blind technique because it relies on the clinician's touch to judge when the catheter is in the correct position to inject the embryos. Many clinicians say this method may be the reason why some embryo transfers fail.
Ultrasound-guided embryo transfer (UGET) has been studied to reduce the number of failed implants. According to clinicians, the use of the ultrasound machine makes it easier to confirm the catheter is in the proper location in the uterus before release.
The Cochrane reviewers analyzed 13 studies that included women who were all undergoing embryo transfer. Participants were randomized into groups being administered either ultrasound-guided or clinical touch embryo transfer technique.
Although no studies reported on live births, the reviewers were able to obtain this information from the authors for two studies. Another six studies reported ongoing pregnancies. Compared to the clinical touch group, the number of live births or ongoing pregnancies for women randomized to the ultrasound group was significantly higher. This means that "for a population of women with a 25 percent chance of pregnancy using clinical touch, this would be increased to 32 percent by using UGET," the reviewers say.
Except for blood on the catheter tip following the transfer procedure, which was more likely with the clinical touch method, the Cochrane reviewers found no statistically significant difference between the two groups in the rate of adverse events, such as ectopic pregnancy, miscarriage and multiple pregnancies.
Experts believe these techniques used by clinicians for embryo transfer will continue to be improved in coming years to increase the number of women who are able to conceive with the procedure.
"IVF, as such, has a small success rate of about 30 to 35 percent and this can further vary in different labs," said Ashok Agarwal, Ph.D., director of research at the Reproductive Research Center at the Cleveland Clinic. "In the future, these methods can further be improved upon to achieve a better pregnancy rate, but that will need multiple studies to make sure the right technique is being used and that evidence shows it is these techniques that are improving the success rate."
IVF was first introduced in 1978, and according to the American Society for Reproductive Medicine, accounts for less than 5 percent of all infertility treatment in the United States. Most couples seeking fertility treatment have success with medications or corrective surgeries.
For women wishing to undergo the technique, UGET appears widely available and physicians agree it has it benefits.
"We have used this technique for a number of years," said Randall Hines, M.D., director of the division of reproductive endocrinology and infertility at the University of Mississippi Medical Center. "My experience tells me that in many cases, clinical touch will be successful, but that ultrasound guidance is most helpful for difficult transfers."
"I would encourage women to ask for this approach, and it is used around the country," Hines said. "As the numbers indicate, the use of this approach would be unlikely to make a tremendous difference in pregnancy rates, but can make a difference in a few cases."
Brown JA, et al. Ultrasound versus 'clinical touch' for catheter guidance during embryo transfer in women (Review). Cochrane Database of Systematic Reviews 2007, Issue 1.
The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.
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