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I got a call from one of my favorite patients last week. She had recently undergone in vitro fertilization (IVF) and we had transferred 2 beautiful 5 day old embryos. She had been reading online and was concerned about our transfer technique. Why didn’t we use ultrasound? Where did we place the embryos within the uterus? Did we use the best technique and why?
The placement of embryos within the uterus (embryo transfer, or “ET”) is the culmination of IVF treatment. After receiving drugs to make many eggs (“ovarian stimulation”), removing the eggs from the ovary (“oocyte retrieval”), and fertilization and growth of the embryos in the laboratory (“embryo culture”) the placement of embryos back in the patient is the final step. Doing it right is critical in achieving pregnancy and one of the factors that separates the best physicians and IVF programs from the pack. Many embryo transfer techniques have been developed over the past 30 years with varying success, but a few things have been shown time and time again:
- Proper placement of the embryo within the uterine cavity makes a difference regarding the outcome of the cycle. Most experts agree that placing the embryos between 1 and 1.5 cm from the top of the uterus (fundus) will achieve the highest possible pregnancy rate. Placement too close to the top or too close to the bottom can lower the chance that the embryo will implant.
- Embryo transfers that are performed without trauma to the uterus are best. Transfers that are deemed “difficult” and cause bleeding and trauma to the cervix and uterine lining (endometrium) result in lower pregnancy rates than uncomplicated, smooth transfers.
- Vaginal and cervical debris can be toxic to embryos and transferring embryos using a “clean technique” improves outcomes.
How Best to Perform the Embryo Transfer?
The best way to accomplish these goals remains the subject of some debate. Many doctors will use an ultrasound to guide the placement of the catheter. Some will perform a “practice” transfer to evaluate the pathway. Some will even perform surgery (hysteroscopy) to evaluate the cervical canal and uterine cavity before the transfer takes place.
In my program, we practice the embryo transfer procedure on each patient by performing a “mock transfer.” This gives me the ability to map out the right pathway and to know exactly where the embryos need to go when the time comes. While ultrasound isn’t such a bad thing, we have found it both unnecessary in accomplishing our goal of performing the best embryo transfer, and cumbersome and uncomfortable for our patients (ultrasound requires a full bladder and a technician to hold a probe firmly on the abdomen). Fortunately, our technique appears to be working! We are very proud to have some of the best IVF pregnancy rates in the state and the country (please check it out – www.sart.org)
So… when I explained to my patient that we did not use ultrasound guidance, she was a bit nervous. However, I was able to explain how the goals of embryo transfer can be accomplished without it and that it can even be a hindrance. The best explanation of all came today – both embryos transferred are growing appropriately and have bounding heartbeats! (It made me forget about the snow and ice I’ve been driving through all week)