Ultrasound beats clinical touch for catheter guidance in embryo transfer

February 26, 2007

Embryo transfer will more likely result in pregnancy if catheter placement is guided by ultrasound rather than clinical touch, according to a study analyzing research through August 2006.

Embryo transfer will more likely result in pregnancy if catheter placement is guided by ultrasound rather than clinical touch, according to a study analyzing research through August 2006.

Dr. Julie Brown of the University of Auckland in New Zealand and colleagues published their results in the Cochrane Database of Systematic Reviews. Their aim was to help better understand one of the many variables involved in successful in vitro fertilization.

Clinics and practitioners all use slightly different methods and have different policies with varying percentages of successful pregnancies. Recent studies have emphasized the importance of catheter placement in achieving successful implantation, but there has been no consensus on the best method for guiding the catheter to just the right place.

Previous studies comparing ultrasound guidance with clinical touch have shown conflicting results, mainly because of inconsistent reporting of randomization, allocation concealment, and power calculation, according to the authors. They compiled a list of 15 studies published through August 2006 in which the two techniques were compared. Thirteen of the 15 studies met the group's requirements for randomization.

None of those 13 studies reported live births, just pregnancies that successfully implanted and the rates of adverse events such as miscarriage, ectopic pregnancy, and multiple pregnancies. Brown and colleagues contacted earlier researchers and were able to obtain data for live births in two of the studies.

Six other studies were still tracking ongoing pregnancies. These findings confirmed that women who had ultrasound-guided embryo transfer were significantly more likely to have live births or ongoing pregnancies at a rate of 32% compared with 25% of the women who had clinical touch embryo transfer. Differences in adverse events between the two methods were not statistically significant, although the clinical touch method showed blood on the catheter tip more often.

The authors suggest that future studies should measure outcome by live births, rather than implantation, since this more accurately reflects the final goal of in vitro fertilization. They also suggest that researchers be more rigorous about reporting details of their studies, such as randomization methods and power calculations.

In the time since this metastudy was conducted, several more articles have been published on this subject. Researchers in Taipei published an article in the journal Fertility and Sterility on Feb. 9, 2007, finding no significant difference in the rates of clinical pregnancy comparing the two methods, but they did not report live births. They did note that both patients and physicians felt more confident about the procedure when using ultrasound to guide the catheter, and they encouraged patients to request the procedure.

The same journal published research from Amsterdam in October 2006 concluding that full measurements of the uterus obtained via ultrasound prior to embryo transfer could be used with statistically similar rates of success as ultrasonographic guidance at transfer. The researchers measured outcomes using rates of clinical pregnancy and not live births, however.