Last week, Spring arrived. Those of you who have been basking in the sunlight, enjoying the smell of cut grass and daffodils while planting next year’s azaleas will appreciate my comparison of planting flowers with doing In-Vitro-Fertilization.
What makes for a successful planting of flowers? Three things. You need good soil. You need healthy bulbs to plant. You need to use good planting technique.
What makes for a successful IVF cycle? Three things. You need a good uterus. You need quality embryos. You need to use proper transfer technique to implant the embryos gently into the optimal location. We’ll discuss uterine factors and embryo factors another time. Today, we focus on the art of embryo transfers.
What’s so difficult about transferring embryos?
Doing a perfect embryo transfer is a challenge for many reasons. Not every uterus is the same. Some tip forwards. Some tip backwards. Some are longer. Some are shorter. Some women have a cervix that is so tight that it will require some forceful dilation to open up. Some have a twisting cervical canal that will require tricky navigation to traverse. The name of the game is to place the embryos in the right place, as gently as possible, without taking too long and without touching the fundus (the top of the uterus).
Imagine taking an empty non-transparent bottle, laying it on its side and blindly poking a pair of tweezers into the mouth of it, with the hopes of dropping a grain of rice into a spot exactly 2 cm away from the bottom of the can. Now imagine doing this without being able to see the entire bottle and without knowing the exact size and shape of the bottle. You can only see the opening and once your tweezers pass through it, your view is obscured and you can only operate by touch. One more rule: You get penalized if you go too far and make contact with the bottom of the bottle.
Let’s make it harder. Imagine that you have to do this for dozens of different bottles, of different sizes and shapes. Also, every once in a while, you will run into a bottle whose neck is so tight that you can’t easily fit your tweezers in. Also, every once in a while, you will run into a bottle whose neck is so twisted that you can’t get the tweezers in without first going up and then turning left at just the exact spot and then twisting back to the right and then down, like some bad puzzle or combination lock.
Now you have a better idea of what it’s like to do embryo transfer.
Why is it so important to do a good transfer?
The transfer can make the difference between a successful cycle and a failed one. The more kindly you treat the cervix and uterus on the day of the transfer, the more receptive the womb will be to good implantation. The more you rough up the uterus, the more irritable it will be and the more likely it will be to contract and slosh the embryo fluid around into the wrong places, possibly even spitting the embryos out completely (although not that likely). The more precisely you transfer the embryos into the optimal site, the better the chance of good implantation. Most will agree that transfer technique is the most important variable related to physician skill and experience in determining the outcome of an IVF cycle and the #3 most important factor overall. (The #1 and #2 factors are the characteristics of the patient and the characteristics of the laboratory). In my program, I don’t try to cherry-pick for the easiest patients. By offering reduced pricing to patients who have failed IVF in the past, I end up attracting the more difficult patients. How likely is it that a patient who has failed elsewhere will get pregnant with my help? Think back to the flower analogy. A lot depends on which of the three factors is the main reason for her past failures. Was it bad soil, bad bulbs or bad planting technique? I’m usually very optimistic about patients who failed IVF in the past due to a previously undetected bad uterine environment. After I fix the uterine problem, I can usually expect a better outcome. I’m also very optimistic about patients who failed IVF in the past with great embryos, but had a bad transfer. There are many tricks I have available to improve embryo transfers and I can usually offer these patients a much better chance at pregnancy. However, for patients who failed IVF in the past because of bad embryos, I’m much less optimistic that anything I can do will make that big a difference in their outcome.
Why is doing a practice transfer beneficial?
Surprises are nice on your birthday or when you play the lottery. But they are not fun when you are doing something critical. We want our medical procedures to be safe, routine and boring with no surprises.
For example, some patients will surprise you with a cervix that is too stenotic (too tight). This is NOT something that you want to discover for the first time on the all-important day of the transfer, especially if the embryos are already in the room, waiting to be transferred, all-the-while being exposed to the random temperature and air mixture of the exam room, rather than being in the tightly-regulated safety of the incubator. It is greatly preferred to learn of this problem well ahead of time, under controlled conditions, so that you can take the necessary steps to address the problem and not have to struggle on transfer day.
I have a consistent policy of doing a practice embryo transfer on every single IVF patient. I’d say that over 90% of the time, we find out to that it was unnecessary, as the transfer ends up smooth and easy. However, in a small, but significant % of patients, it will make a world of difference between having an easy, worry-free transfer vs struggling through a sweating-bullets, cursing-to-yourself transfer which in turn can make the difference between a successful pregnancy vs a failed cycle. Are you one of those people who when faced with the most important job interview of your life will make the effort of driving to the location a week beforehand, assessing the traffic, gauging the travel time and scoping out the parking, so that the actual day will be as stress-free as possible? If so, you would understand the concept of doing practice transfers ahead of time. However, if instead, you are the carefree just-wing-it type, then you will do fine 90% of the time. But 10% of the time, you’ll end up getting lost or unexpectedly delayed, arriving late for the interview and blowing your chances of making a good impression, thereby costing you that job you wanted so badly. 
What are some important things you can discover during a practice transfer?
As I mentioned earlier, some patients have a cervix that is so stenotic (tight) that it becomes impossible to do a transfer. There is a RE from whom I’ve inherited many failed patients, several of whom had transfers that were so difficult that they had to be put under general anesthesia. This is something that I’ve almost never heard of anyone else doing, except for this particular doctor. The majority of those patients have wound up getting pregnant with my help. There are many tactics of getting around the problem of a really difficult cervix.
- Dilatation. By using a set of increasingly large dilators, the cervix can be made more accommodating. I repeat that this is something that you want to do ahead of time – not on the day of the transfer. True, sometimes, you dilate the heck out of the cervix and it still creates a bit of a struggle on the day of the real transfer, because it shrinks back. However, this still beats being caught fully by surprise.
- Tension suture. One trick I rarely use is to place a suture on the cervix. This is helpful for a cervix that is too sharply bent. By pulling on the suture, I can straighten out the cervix and help pass the catheter more easily. In the US pictures below, you see that the canal is just slightly curved. However, some patients have a cervix that is so sharply curved that it makes a 90 degree angle. Now you don’t want to place the stitch on the day of the transfer because that hurts a lot and it angers the uterus. By anticipating this problem, I can place the stitch at the time of the patient’s egg retrieval while she is under anesthesia. Then, on the day of the transfer, I have a painless handle by which to straighten out the cervix. After the transfer, I cut the suture and remove it.
- Laminaria. This is a commonly used gynecological device, although technically it’s more of a biological entity rather than a device. It’s a little stick-like thing that is harvested from a particular type of sea creature. When you put it into the cervix, it will absorb water and get really fat overnight. This is a very safe, gradual way of dilating the cervix. Again, this is of no use if you wait until the day of the transfer to find out that the cervix is too tight.
- Proper mapping. Sometimes, the cervix is not too tight, but rather, too twisted. If you have a cervix shaped like an S, for example, you have to map it out so you know when to turn up and when to turn down, when to turn left and when to turn right, like in that Kenny Rogers song.
- Giving up on the cervix. There is that one in a 1000 women whose cervix is completely impassable. I had a patient whose cervix made a 180 degree hairpin turn. I did a saline-contrast ultrasound and a hysteroscopy on her to confirm this. I consulted many of my colleagues and mentors who were all stumped. I eventually wound up doing an old procedure called GIFT (Gamete IntraFallopian Transfer), in which I didn’t even bother trying to pass through the cervix, choosing instead to put the eggs and sperm into her tubes. She got pregnant in what is likely the last GIFT I will ever do, so I might be able to retire with a 100% batting average there. One other option for these patients is to try a transmyometrial transfer in which you push a needle THROUGH the wall of the uterus. I’ve never done that, but I hear from those who have tried it that the success rate is low. The last resort would be to use a surrogate, ie use some OTHER woman’s uterus to carry it.
There are a few other tricks that I’ve learned over the years, but a lot comes from practice and taking advantage of a whole armamentarium of different catheters.
What is an ultrasound-guided transfer?
In the past, all transfers were done blindly. Some RE’s still do their transfers blindly to this day. I can’t understand why. Think back to the model I described earlier of blindly putting a grain of rice into a bottle. Now how much easier do you think it would it be if you had a special camera that could show you exactly where you are at all times. Well we do have such a magical device and it’s called ultrasound.
In these pictures, we see the uterus. We come in with our cathether from the cervix at the top left (red arrow) and we are hoping to land at the sweet spot designated by the X. This is where the embryos want to go. The brown line shows the outline of the uterus.
Every step of the way, as I slowly advance the catheter, I can see where I am and where I want to be.
Ultrasound-guided transfers are not some fancy gimmick. While I can’t prove yet that the location I choose is immensely better than another spot a half centimeter deeper or shallower, I can guarantee that the embryos are not being pushed too deep into the wall of the uterus. I can guarantee that they are not being put too shallow into the lower uterine segment. I can guarantee that the catheter is not curling around and coming back to spit the embryos into the cervix. My own IVF success rates went up after adopting this technique several years ago. (Last year saw 59 pregnancies out of 100 transfers for me) as did those of my colleagues who adopted this technique. I apologize if this is sounding too self-congratulatory, but I have a very strong opinion on the huge advantages of doing things this way and I wanted to provide some convincing evidence.
Why doesn’t everyone do their transfers under US-guidance?
You would have to ask them. I wonder that myself. I have some theories. One is that it’s hard to change old habits. There have been people around who were doing IVF before I was in high school and they will claim that they can do a transfer blindly as well as I can do one under US visualization. Who am I to argue with them?
Now, some people try to do them under ABDOMINAL ultrasound-guidance. This is still better than doing it blindly, but it has a few disadvantages. One is that it requires an additional set of hands to hold the ultrasound and you’re at the mercy of a technician or nurse who may or may not be that good at it. The other big disadvantage of doing it under abdominal ultrasound guidance is the need to have the bladder uncomfortably full, which can eventually progress to inhumanely full, according to some patients who have had it before. In case I didn’t mention it specifically, I advocate doing the transfers under VAGINAL ultrasound-guidance. In general, you get a much clearer picture and for two types of patients (those with a retroverted uterus and those who are obese), the vaginal approach just blows the abdominal approach right out of the water.
This brings us to the main reason why not everyone does it this way. It’s not that easy to master (at first, anyway). Before I first started using this technique about seven years ago, I was intrigued to hear about it. How can you fit a speculum, an embryo catheter and an ultrasound transducer all in the vagina at the same time? It didn’t sound possible. However, with a lot of practice, I can now do an ultrasound-guided transfer in close to the same time that it takes someone to do a blind transfer. Maybe it consumes an extra 2 minutes of my time for each transfer, but again, the extra effort is well worth it to the patient.
The last answer to why not everyone does US-guided transfers is this. More and more people ARE doing them. My closest colleagues all do some sort of US guidance, although many still like the abdominal approach. So in reality, I would guess that more than half of all RE’s in the US ARE using US-guidance. I will be happy to hear some day that all of them are doing it, but to this day, I know of some who are still doing things blindly.
How does one get better at doing embryo transfers?
When I first wanted to learn US-guided transfers, I practiced by doing ultrasound guided IUI’s. The difference between an IUI and an embryo transfer is like the difference between dropping a grain of rice into a precise spot in the bottle vs shooting a syringe full of water into the bottle. IUI’s don’t need to be precisely placed to be successful. But for quite some time, whenever I did an IUI, I would do it under US-guidance just for the practice. To this day, this is how I train RE fellows and interested residents how to do US-guided transfers. In fact, for some patients with difficult IUI’s, I will, at their request, do the IUI under US-guidance. As I said, it takes me an extra 2 minutes, but the extra hard work is well worth it. I point out the story of Steve Nash. Most of you will know him as a very hard-working NBA basketball player who in 2002, made 49 consecutive free throws without missing. He also made 47 straight in 2003. Those who laughed at me for so tediously practicing transfers are the same type of people who laughed at Steve Nash for staying late after basketball practice and shooting 100 free throws every day. A waste of time? Think what you want.
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