Ultrasound-guided embryo transfer improves pregnancy rates
NEW YORK (Reuters Health) - Pregnancy rates are higher after embryo transfer guided by ultrasound than by clinical touch, according to a report in the January 24 issue of the <i>Cochrane Database of Systematic Reviews.</i>
Previous studies comparing ultrasound guidance with clinical touch for embryo transfer yielded conflicting results, explain Dr. Julie A. Brown from University of Auckland, New Zealand and colleagues. They therefore systematically reviewed the literature to evaluate these methods, and identified 13 eligible randomized, controlled trials.
Clinical pregnancy rates were nearly 50% higher for women randomized to ultrasound-guided embryo transfer than for women randomized to clinical touch embryo transfer, the authors report.
The two methods of embryo transfer did not differ in the incidence of multiple pregnancy or ectopic pregnancy, the results indicate, and there was no difference in the incidence of spontaneous miscarriage.
There was no clear difference between the two groups in the difficulty of transfer, the report indicates, and none of the studies reported on fetal abnormalities.
"The exact mechanism by which ultrasound-guided embryo transfer increases pregnancy rates remains unclear," the investigators say. "The main suggestions remain the confirmation of the catheter in the uterine cavity, 'ease of transfer' positioning of the catheter, and avoiding touching the fundus or indenting the endometrium."
The authors add, "Future research should report on the live birth rate per woman randomized as an outcome measure which is of importance to the target population."
Cochrane Database of Syst Rev 2007, Issue 1. Article no.: CD006107.