Embryo Implantation Process

Much has been written regarding the proper time of embryo transfer, we like to think of Day 5 embryo transfer as an important tool to be used when circumstances dictate.


Regardless of the day of transfer, the procedure is similar. Unlike the egg collection, the patient does not need to have an empty stomach and it’s completely reasonable to have a normal breakfast and lunch. We usually perform our embryo transfers in the afternoon. We ask the patient to start filling her bladder shortly before the embryo transfer, because we perform our transfers under ultrasound guidance. Since we need to place a speculum for the embryo transfer, we need to use an abdominal ultrasound probe and not a vaginal probe. Unlike the vaginal probe, which works best when the bladder’s empty, the abdominal probe works best when the bladder is full.

The Transfer Procedure

Unlike some other programs, we do not permit a family member to accompany the patient to the transfer room. Since it is in such direct contact with the laboratory, we wish to avoid the more than 1,000 extra contaminations of the laboratory that occurs each time a person enters. We recognize that it may be more comfortable to undergo transfer accompanied by a family member, however we insist upon this compromise in order to protect the environment in the laboratory.

Except in very rare instances, the embryo transfer is performed without anesthesia. The embryologist will again verify the identification of the patient and verify the number of embryos being transferred.

In our procedure room, we have a closed-circuit television system that allows the people in the procedure room to see what’s going on under the microscope in the laboratory on the other side of the wall. While we setup, the patient can see the embryos placed into a single small drop of media so they can be drawn up together by the catheter. Just prior to loading the catheter with the embryos, we have the patient verify that her own name is etched into the bottom of the Petri dish containing the embryos.

We do our embryo transfers under ultrasound guidance. This is a controversial manoeuvre, but we feel that it helps us in some of our more difficult transfers. While a specially-trained nurse or ultrasound technician lines up a good picture of the uterus and its lining, the physician places a speculum and gently clears some of the mucus off the cervix. In many cases we use an empty catheter to quickly map out the route and to demonstrate and verify that the measurements we had previously had in the office were correct.

When we are comfortable that all is in place for an effective transfer, we ask the embryologist to load the embryos into the catheter. This is also visible on the closed-circuit TV. The embryologist then walks into the room, for one last time checks the identity of the patient and then hands the catheter to the physician who gently threads it through the cervix. On the ultrasound we can usually see the tip of the catheter as it approaches the top of the uterus. We generally stop the top of the catheter at 1 to 11/2 cc from the top of the uterine cavity and gently release the embryos. We slowly remove the catheter and hand it back to the embryologist, who reexamines the catheter under the microscope to insure that none of the embryos are returned with it. In the cases when an embryo does return with the catheter, we simply reload the catheter and perform the procedure again. When we are confident that all of the embryos have been transferred successfully, we remove the speculum, transfer the patient to a stretcher and bring her to a recovery area for a half hour.

Dealing With Any Problems During The Transfer Procedure

We need to make a distinction between a difficult embryo transfer and a traumatic embryo transfer. A difficult transfer that still results in the embryos reaching the uterfundus without damaging the lining and without causing bleeding will not have an adverse effect on the outcome of the cycle. We may go through five or six different manoeuvres to insure that the catheter gets to where it needs to go: we may change speculums, press on the bladder (which we hate to do knowing the bladder is full), place the outer “guide” portion of the catheter in while the embryologist loads the inner portion, bend the catheter into different shapes, press the uterus either up or down with a cotton sponge attached to a forcep, or have the patient gently shift position. None of these maneuvers should be problematic for the uterus or for the embryos.

Of course with so much on the line, it’s understandable that a patient may become tense or anxious that the transfer seems to be taking a long time. Relieving the stress is our job. If the transfer is taking a little bit of extra time, we like to let you know what’s going on and explain to you each maneuver as we do it. After many embryo transfers, there’s almost nothing we have not seen.

Extremely and rarely we come across a cervix we simply cannot work with. Usually we pick this up in our initial physical exam when we do a trial transfer in the office. Very rarely we find that we cannot implant the embryos into the uterus at the time of the embryo transfer. In all of these instances we have gone as far as to operate on the cervix to open up the passageway. The preferred technique is to use a hysterscope with a tiny scissor that allows me to trim the narrowed area to allow the catheter to pass. If we find during the transfer that we cannot pass the catheter, we proceed to freeze the embryos, operate on the cervix and then return to transfer the frozen embryos. The results of these cases have been uniformly good.

There are other options for dealing with a difficult cervix. In some countries a transmyometrial approach is used. This involves using the vaginal ultrasound and the same needle guide that we used for the egg retrieval, lined up to pass a thin, hollow needle through the wall of the uterus and into the embryo into the uterine cavity. A thin plastic tube containing the embryos is then passed through this needle and into the cavity. We find it more traumatic than we wish it were. Other options include dilating the cervix prior to the transfer or placing a laminarian, an organic product that swells when it absorbs fluid and opens the cervix. Our problem with dilating the cervix or using a laminarian is that we don’t wish to place a foreign body into the uterine cavity a few days prior to the embryo transfer. It could be a route for bacteria to go into the cavity or it could cause the release of substances that may make the uterine cavity less hospitable to embryos. Certainly not everyone agrees with me and there is room for differences of opinion in our field.

It’s important for everyone to realize, especially we MD’s that difficult cervixes are merely one form of normal within nature. When the human body was designed, embryo transfer was not very high on the list of priorities and cervixes that are completely normal in every way, shape, form and function may be difficult routes of passage for embryo transfer.