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BackTable / OBGYN / Article
Ovarian Tissue Cryopreservation: Techniques, Reversal & Accessibility
Taylor Spurgeon-Hess • Jul 12, 2023 • 36 hits
While navigating the complex landscape of oncofertility, clinicians find themselves employing intricate procedures to safeguard fertility, particularly through ovarian tissue cryopreservation. These procedures provide new avenues for patients at high risk of infertility. One aspect of this process includes the careful extraction and processing of ovarian tissue, a technique that requires immense precision and understanding of the ovary's anatomy. In contrast, the reversal of this procedure—reintroducing the cryopreserved tissue to the patient—demands surgical expertise, demonstrating an interplay between innovative techniques and the body's natural responses. The advent of these procedures also prompts questions about their accessibility and possible expansion to institutions lacking resources, thus emphasizing the necessity of broadening the reach of these life-changing services in oncofertility.
This article features excerpts from the BackTable OBGYN Podcast. We’ve provided the highlight reel in this article, but you can listen to the full podcast below.
The BackTable OBGYN Brief
• Complete ovarian removal is a common approach in ovarian tissue cryopreservation, despite ongoing debate around optimal tissue extraction methods. Ovarian tissue cryopreservation involves bisecting the ovary, removing the medullas, and cutting the cortex into strips.
• The removal of the ovary is performed in the operating room, followed by subsequent procedures in the hands of reproductive endocrinology and infertility specialists or trained pathologists.
• The fallopian tube is preserved during the procedure to allow for spontaneous conception post-transplantation, which has led to a significant number of live singleton births.
• Ovarian tissue transplantation is achieved through laparoscopic procedures to create a pouch or pocket in the peritoneal pelvis for the ovarian strips. Two to three strips are typically placed in the pouch during transplantation due to the limited viability duration of the tissue.
• Different transplantation techniques exist, including insertion of the tissue into slits in the remaining ovary's cortex or decorticating the remaining ovary and attaching thawed strips. Despite the diversity of techniques, success rates across these methods are currently similar.
• The rate of follicular atresia post-transplantation is highly dependent on the robustness of the vasculature, highlighting the importance of proper transplantation procedures.
• Inter-institutional collaboration can make ovarian tissue cryopreservation more accessible to smaller institutions. Removal of ovaries for cryopreservation can be conducted in one institution, with the tissue then sent to a specialized center for processing.
Table of Contents
(1) Ovarian Tissue Cryopreservation Extraction Technique
(2) Reversing Ovarian Tissue Cryopreservation: Techniques and Considerations
(3) Expanding Access to Oncofertility Services
Ovarian Tissue Cryopreservation Extraction Technique
The procedure of ovarian tissue cryopreservation, while intricate, plays a vital role in preserving fertility for high-risk patients. The entire ovary is usually removed, despite ongoing debate about whether cortical biopsies or complete removal is most effective. The procedure primarily involves bisecting the ovary, removing its inner medullas, and cutting the cortex into specific strips, given that follicles predominantly reside in the cortex. This procedure occurs post-retrieval, with the ovary initially removed in the operating room and then transported for subsequent procedures. Ensuring minimal additional bleeding is crucial, given the patients' typical pancytopenia, and energy sources with minimal spread are employed to prevent damage to the fallopian tube and ovarian cortex. Notably, the fallopian tube is left intact to enable spontaneous conception post-transplantation, a factor that has led to half of the live singleton births among patients who underwent this procedure.
[Dr. Mark Hoffman]
Talk us through that procedure when you remove the ovary or remove ovarian tissue to replacement. Talk us through that.
[Dr. Leslie Appiah]
I'm glad you asked, Mark. One of my favorite topics. When we remove an ovary, we are not able to freeze an entire ovary as it is because of the diameter and the width of the ovary. Our cryoprotectants or our freezing agents can't traverse the width of the ovary. We bivalve the ovary in half.
[Dr. Mark Hoffman]
You take out the entire ovary.
[Dr. Leslie Appiah]
We take out the entire ovary and that is actually a subject of debate. We may potentially remove strips of the ovary, and that's called taking cortical biopsies, or we may remove an entire ovary. There are some investigators who recommend removing just strips of the ovary for patients who are not at the highest risk of infertility. Some of us feel differently and we feel that perhaps we should only be doing ovarian tissue cryopreservation for those patients who are at the highest risk. In that case, we know that they have an 80% to 90% chance of infertility. It would behoove us to obtain as much tissue as possible. That means remove an entire ovary.
At the University of Colorado, we are of the school of thought of removing an entire ovary for patients who are at the highest risk. When we remove the ovary, we bivalve the ovary, we remove the medullas, the inner part of the ovary, because follicles are not contained there or so we believe. The follicles are primarily contained in the cortex. We then cut the cortex into strips of a very specific diameter; half a centimeter wide to a centimeter long to two millimeters wide.
[Dr. Mark Hoffman]
Done in the OR or this is all done after?
[Dr. Leslie Appiah]
Done after retrieval. The ovary is removed in the OR and then the ovary is transported to reproductive endocrinology and infertility specialists or pathologists who are trained in this technique. The procedure then happens there.
[Dr. Mark Hoffman]
Are you using energy, removing the ovaries like you normally would for an ectomy for anybody else?
[Dr. Leslie Appiah]
We are, because these patients, as you can imagine, have pancytopenia, they're anemic, they have thrombocytopenia. We want to make sure that we don't cause any additional bleeding and so we do use a heat source. We are getting better and better at using sources that have minimal spread so that we don't harm the fallopian tube or the blood vessels to the fallopian tube because we do leave the fallopian tube in place.
[Dr. Mark Hoffman]
Oh, interesting. I'm trying to figure out.
[Dr. Leslie Appiah]
This is the surgeon in Mark. He's thinking this through. Then we also don't want to harm the cortex of the ovary when we're transecting. This is far easier to do in adult patients where there's enough distance in the mesosalpinx. Pediatric patients, there've been some suggestion that maybe in pediatric patients we should remove the tube and the ovary together because we may end up damaging the tube if left behind, so why leave behind a damaged tube?
Well, the reason we should leave behind a tube is because we prefer to transplant the tissue back into the pelvis near the fallopian tube where we removed the ovary because half of the pregnancies, or half of the live births, the singleton live births have been in patients who have conceived spontaneously. If we leave the tube in place, then patients can have intercourse and conceive.
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Reversing Ovarian Tissue Cryopreservation: Techniques and Considerations
Reversing the process of ovarian tissue cryopreservation, to initiate family planning after cancer treatment, involves strategically transplanting ovarian strips back into the patient. Laparoscopic techniques are employed to create a pouch or pocket in the peritoneal pelvis, into which two or three strips are placed. Given the finite viability of the transplanted tissue, between six months to eleven years based on current data, not all the strips are transplanted at once. Following transplantation, angiogenesis occurs within 30 to 90 days, and the ovary begins to ovulate. There are several transplantation techniques, including inserting the tissue into slits made in a remaining ovary's cortex, or completely removing the cortex of an in-situ ovary and attaching the thawed strips. Despite the complexity, each of these techniques has shown similar success rates. It's essential that only those with surgical expertise and the support of a specialized team perform the transplantation due to its highly technical nature.
[Dr. Mark Hoffman]
Ovary comes out, chopped up, frozen, freezer, cancer treated, patient's ready to start a family. How do you reverse that?
[Dr. Leslie Appiah]
Exactly. We will use the same incisions typically, so laparoscopic procedure ideally and create a pouch or pocket in the peritoneum of the pelvis, so near the fallopian tube in the ovarian fossa. We just place two or three strips. In an adolescent or an adult female, you may have 15 to 20 strips depending on the age. We don't want to put all the strips back in one time because there's just a finite duration of viability for the tissue. That duration is anywhere from 6 months to 11 years based on the data. We'll place two or three strips into that pocket or that pouch. You can suture the pouch closed, put [unintelligible 00:22:02], use surgical glue, and then within 30 to 90 days, angiogenesis occurs, and the ovary begins to produce hormone and begins to ovulate. It is amazing.
[Dr. Mark Hoffman]
No way. Wait, you're just sewing it inside the pelvic sidewall?
[Dr. Leslie Appiah]
Yes, pelvic sidewall.
[Dr. Mark Hoffman]
Just stick it in there, close it over.
[Dr. Leslie Appiah]
Yes. Get it in there anywhere you can. There are some other techniques that are a little bit more sophisticated where we always try to leave one ovary behind in the event that there's spontaneous recovery. There is a technique that is described where one could create slits within the ovarian cortex of the remaining ovary, undermine the cortex, and then just slide each strip of thawed cortical tissue beneath the surface. The idea is that that blood supply may be more robust and that you may have success there. There is also a third technique where a surgeon may decorticate, so remove the cortex of the remaining in situ ovary completely to allow exposure to that vascular bed and then suture ligate these thawed strips of--
[Dr. Mark Hoffman]
It's like a face transplant.
[Dr. Leslie Appiah]
Exactly. Just like that.
[Dr. Mark Hoffman]
You're just skinning the ovary and putting the new cortex on top of it.
[Dr. Leslie Appiah]
Yes. Now, when they look at all three approaches, the success rates are similar. Now, you have 200 patients born worldwide, you have to say, do we have the power to really say that they're equivalent? Thus far it does not seem that any procedure is superior to the other. I will say that the face plant for the ovary and the pockets requires a big rescission and microsurgical dissection and technique and so you really need someone who has a surgical expertise. The rest of us Average Joe Schmos surgeons, can do a laparoscopic procedure where we create the pouch and place the tissue there.
[Dr. Mark Hoffman]
We had Dr. Elliott Richards from Cleveland Clinic come and talk to us about uterine transplant. That was a whole other series of problems trying to figure out what needed to happen to get all of that going, but this is fascinating. The idea that you can just throw it back in there and it comes back alive, putting that tissue in the pelvic sidewall, how does it ovulate? Does it just pop through the peritoneum?
[Dr. Leslie Appiah]
It pops through the peritoneum.
[Dr. Mark Hoffman]
Finds a way.
[Dr. Leslie Appiah]
You got it. It pops right through the peritoneum. They've done some sophisticated ultrasound studies to see that occurring. Very early on there was a debate, oh, is it really the tissue transplanted or is it the remaining ovary? They've shown that. They've shown ovulation coming from that tissue.
[Dr. Mark Hoffman]
I guess if you have somebody with no ovaries, can you put a--
[Dr. Leslie Appiah]
Yes. They've done that. They've done those studies. The success rate is 29% of 41% depending on the age of the patient at the time of retrieval, because there's more tissue for an older patient, but there are more eggs, so in a younger patient. Even though children have really small ovaries, there are millions of follicles there. The success rate depends on size of the tissue and then the center that is performing the transplantation. I think that's important for me to say because I would recommend that surgeons not do this procedure to transplant the tissue if they have not developed the expertise.
Most gynecologic surgeons and general surgeons can remove an ovary, but transplanting the tissue is going to require more than just putting the tissue back. We may need to look at the vascular bed. We are trying to identify agents such as anti-Müllerian hormone to place the tissue in prior to transplantation. How do we support the tissue when it's transplanted into the pelvis? Because the follicular atresia and the loss of follicles is pretty rapid once the tissue is transplanted, if the vasculature is not robust. We don't want surgeons to take this on because they want to help patients. We want to make sure that this happens at centers of excellence and places where there is a team to do this well.
Expanding Access to Oncofertility Services
Accessibility to ovarian tissue cryopreservation services is a paramount concern, and smaller institutions lacking resources can benefit from inter-institutional collaboration. Ovaries can be removed, placed in holding media, and transported to specialized centers for tissue processing. For example, in Colorado, the tissue is shipped to University of Pittsburgh for processing and long-term storage at ReproTech, an organization recognized for its excellence in fertility preservation. A similar model can be replicated in other institutions to expand the reach of this vital service. Oncologists can contact a surgeon to remove the ovary from a patient at risk, and from there, the process can unfold seamlessly. While currently an academic pursuit, there's a call for more centers to contribute to this practice while following the science and maintaining the focus on patient care.
[Dr. Leslie Appiah]
Yes, and I want to comment on that because we do want to make ovarian tissue cryopreservation accessible to smaller institutions or institutions that don't have the resources to have the Cadillac version of things as we do here in Colorado. It is possible to remove an ovary, place the ovary in holding media and transport the ovary to another center. Actually, at the moment, we transport our tissue to University of Pittsburgh, to Kyle Warwick's Group, and they process the tissue there and then they send the tissue to a long-term storage facility. Typically, we use an organization called ReproTech, and I'm going to call them out because they are an amazing partner and do amazing things for these patients. That's our long-term storage facility. At the University of Kentucky, where we started the program and things have been in transition for a while, you, Mark, can remove an ovary.
UPMC will send the shipping materials to you. You can send the ovary to UPMC. They will establish a relationship with the patient as will ReproTech. Then that patient has had their fertility preserved and when they're ready to have the tissue transplanted back, there are several centers that the patient will then be able to go to to say, "I would like to have my tissue transplanted here."
[Dr. Mark Hoffman]
That changes everything though, honestly. I think the idea that there are a small number of centers with a very finite number of surgeons and teams that are doing the incredible work that you're doing, but the idea that now that someone like me can just take an overview out and send it somewhere, now that person's got access to their future fertility.
[Dr. Leslie Appiah]
Exactly. It should be that simple. It should be the oncologist has a patient. The oncologists know the risk stratification, they know which patients are at harm and they can contact a surgeon and say, "This patient's at harm. We've talked about ovarian tissue, cryopreservation. They would like to participate," and then we can take it from there.
[Dr. Mark Hoffman]
Are there companies doing this or is this all academic?
[Dr. Leslie Appiah]
It's academic for now. For now, it's academic, but in medicine, when we don't do what we're supposed to do, industry will do it for us. I recommend that we do this as academicians so that we can follow the science around it. It would be my recommendation.
[Dr. Mark Hoffman]
How many places do you estimate are sending ovaries to a place like Pittsburgh? Or is there not a place like Pittsburgh? Is Pittsburgh yet? Are there other places you can send it?
[Dr. Leslie Appiah]
There are other places. One can send tissue to Northwestern. I believe University of Michigan is bringing their program up in a year. Colorado will be a regional center.
Podcast Contributors
Dr. Leslie Appiah
Dr. Leslie Appiah is the director of the fertility preservation program and the chief of the division of academic specialists in OBGYN at the University of Colorado Anschutz.
Dr. Amy Park
Dr. Amy Park is the Section Head of Female Pelvic Medicine & Reconstructive Surgery at the Cleveland Clinic, and a co-host of the BackTable OBGYN Podcast.
Dr. Mark Hoffman
Dr. Mark Hoffman is a minimally invasive gynecologic surgeon at the University of Kentucky.
Cite This Podcast
BackTable, LLC (Producer). (2023, May 4). Ep. 22 – Oncofertility [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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