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No good reason to not use ultrasound during embryo transfer, expert says



CORONADOAtraumatic embryo transfer is essential to success of in vitro fertilization (IVF), and ultrasound guidance maximizes the chance for this to occur, according to William Schoolcraft, MD, HCLD.

At a meeting on IVF and embryo transfer sponsored by the University of California, San Diego, Dr. Schoolcraft said that ultrasound-guided embryo transfer helps clinicians avoid difficult transfers, minimizes contamination with blood, facilitates proper placement of the catheter tip, and minimizes the stimulation of uterine contractions. “We know that contaminating the catheter either with blood or mucous or endometrial tissue lowers clinical pregnancy rates, compared to a clean catheter,” said Dr. Schoolcraft, founder and medical director of the Colorado Center for Reproductive Medicine, Denver.

“Ultrasound guidance can help you follow the contour of the cervix and avoid touching the fundus. Your catheter should be free of blood, mucous, or endometrial cells when the embryologist examines it,” he said. In his clinical opinion, it’s hard to argue against using ultrasound guidance for embryo transfer. “It’s also very popular with IVF patients, because they get to visualize the transfer and have some reassurance that the embryo is delivered to their uterus,” he said.

The potential benefit of using three-dimensional ultrasound for embryo transfer is less clear. “It does require more expensive equipment and it’s a little more skill dependent, but in a randomized trial it didn’t lead to any difference in outcomes,” Dr. Schoolcraft said. “I think if you’re good with two-dimensional ultrasound, three-dimensional ultrasound doesn’t seem to have much benefit in terms of pregnancy outcomes.”

In a study published in 2017, researchers from Barcelona analyzed 7,714 embryo transfers to determine the impact of maneuvers during embryo transfers on the pregnancy rate (Fertil Steril. 2017 Mar;107[3]:657-63.e1). Using the direct embryo transfer as a reference, each instrumentation needed to successfully deposit the embryos in the fundus served as an index of the difficulty of transfer. A difficult transfer occurred in 7.7% of cycles, and the researchers found that the clinical pregnancy rate decreased progressively with the use of additional maneuvers during embryo transfer. Specifically, the clinical pregnancy rate was 39.4% when no additional maneuvers were required, 36.9% when an outer catheter sheath was used (odds ratio, 0.89), 31.7% when a Wallace stylet was used (OR, 0.71), and 26.1% when a tenaculum was used (OR, 0.54). “I think without question, avoiding a difficult transfer is important and certainly a key to our success,” said Dr. Schoolcraft, who was not involved with the study.

The ideal depth of embryo transfer is “a bit complicated,” he said, but according to the best available evidence, a depth of 15-20 mm from the fundus by ultrasound guidance appears to optimize implantation by avoiding the lower cavity where implantation is compromised. This range of depth also avoids problems with upper cavity transfers, including trauma, contractions, and tubal pregnancy. “I think that transfers which are close to the fundus, and possibly in some cases touching the fundus, may lead to uterine contractions, plugging the catheter with endometrium and generating bleeding,” Dr. Schoolcraft said. He pointed out that during natural pregnancies, embryos implant in the upper fundus nearly 90% of the time, compared with 66% of the time during IVF pregnancies. “To mimic Mother Nature we don’t want to be too low, either,” he said. “We all know that placenta previa is increased with IVF. This may be due to placing the embryos too low.”

Dr. William Schoolcraft, founder and medical director of the Colorado Center for Reproductive Medicine, Denver.

Dr. William Schoolcraft

According to Dr. Schoolcraft, many published studies have found that significantly higher pregnancy rates occur with routine bladder distension prior to embryo transfer, probably because of the smooth and easy insertion of the embryo transfer. A Scandinavian meta-analysis found that the odds ratio favoring ultrasound guidance and a full bladder for ongoing pregnancy was 1.44 and clinical pregnancy was 1.55, which is similar to that seen during an earlier review from The Cochrane Collaborative, with an OR of 1.47 for ongoing pregnancy and OR 1.53 for live birth (Cochrane Database Syst Rev. 2016 Mar 17. doi: 10.1002/14651858.CD006107.pub4).

Dr. Schoolcraft reported having no financial disclosures.

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