Ultrasoundguided Embryo Transfer

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Ultrasonographic imaging is now being used to guide the placement of the embryo transfer catheter in an effort to facilitate optimal embryo placement and enhance the probability of a successful pregnancy (127-137). Transabdominal ultrasound guidance is a more common means of directing the embryo transfer catheter, however, transvaginal scanning may also be used (134,138). It is also important to note that ultrasound guidance of embryo replacement does not prevent the establishment of an ectopic gestation (139). The recent advent of easy-to-use and relatively inexpensive 3D ultrasonography has facilitated a new wave of enquiry into the utility of 3D imaging to guide the embryo transfer catheter (136,140). Early impressions are that 3D imaging may be beneficial in identifying the site of optimal embryo placement with respect to anatomic variations in individual women.

Clinical and laboratory preparations for embryo transfer are the same, regardless of whether the transfer is to be ultrasound guided or not. Patients are placed in the lithotomy position and the cervix exposed using a bivalve speculum. Mucus and secretions are removed using culture media and the tip of the transfer catheter is introduced into the os cervix. The addition of transabdominal ultrasound imaging simply involves placement of the transducer, typically using 3-4 MHz large aperture probe, on the lower abdomen and pelvis in the sagittal plane and imaging the full sagittal plane of the uterus and cervix through a full bladder window (Fig. 7) (133,141,142). Most standard embryo transfer catheters are easily visualized as a pair of highly echogenic lines within the cervix; however, a transfer catheter system has been developed to increase the ease of imaging (143). Once the catheter has been identified, the tip may be carefully guided through the uterine lumen using real-time imaging. Once the clinician attains the optimal place with in the uterus, the embryos are gently expelled (144). Opinion on exactly what optimal placement means is varied (145-148). The fluid droplet containing the embryos is visualized as a very small hypoechoic blip deposited at the tip of the transfer catheter. Transvaginal ultrasound guidance is done in a similar fashion, except that a probe designed for intracavitary use is introduced through the speculum and placed into contact with the anterior vaginal fornix (134,138). The transfer catheter is visualized and the tip guided to the optimal uterine location for embryo deposition.

There is a measure of controversy regarding the usefulness of ultrasonographic guidance during embryo transfer versus non-visually guided clinical touch (131,137,141,149-155). Some clinicians prefer to rely on ultrasound guidance for mock transfers in cycles before IVF and embryo transfer and clinical touch in the actual procedure, others use ultrasound guidance for all procedures, and still others make a decision regarding its use based on whether or not the transfer is likely to be classified as easy or difficult (137,144,155). Two recent meta-analyses and a subsequent randomized controlled trial have been interpreted to mean that transabdominal ultrasound guidance versus clinical touch for embryo transfer significantly increased the pregnancy rate, although the rates of miscarriage, ectopic pregnancy, and multiple pregnancy were not affected (154,156-158).

Figure 7 Midsagittal view of the uterus imaged with transabdominal ultrasonography during embryo transfer. The transfer catheter is visualized as the highly echogenic line in the middle of the uterus. Calipers (+) mark the distance from the tip of the catheter to the fundus. The image documents optimal replacement of the embryos. Source: Image courtesy of Dr. Roger Stronell.

Figure 7 Midsagittal view of the uterus imaged with transabdominal ultrasonography during embryo transfer. The transfer catheter is visualized as the highly echogenic line in the middle of the uterus. Calipers (+) mark the distance from the tip of the catheter to the fundus. The image documents optimal replacement of the embryos. Source: Image courtesy of Dr. Roger Stronell.

Figure 8 Gray-Scale and Spectral Doppler image of an embryo 5 weeks post transfer. The gestational sac, embryo and yolk sac are visualized in the top half of the image. the Dopplar gate is placed directly over the embroyomic heart and the resulting spectral doppler trace is seen in the lower half of the image reflecting cardiac activity.

Figure 8 Gray-Scale and Spectral Doppler image of an embryo 5 weeks post transfer. The gestational sac, embryo and yolk sac are visualized in the top half of the image. the Dopplar gate is placed directly over the embroyomic heart and the resulting spectral doppler trace is seen in the lower half of the image reflecting cardiac activity.

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A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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