Ovarian tissue cryopreservation and transplantation among alternatives for fertility preservation in the Nordic countries - compilation of 20 years of multicenter experience.
BACKGROUND
The aim of this study is to report the current status of ovarian tissue cryopreservation among alternatives for fertility preservation in the Nordic countries.


METHODS
A questionnaire was sent to 14 Nordic academic reproductive centers with established fertility preservation programs. It covered fertility preservation cases performed up to December 2014, standard procedures for ovarian tissue cryopreservation and oocyte cryopreservation and reproductive outcomes following ovarian tissue transplantation.


RESULTS
Among the Nordic countries, Denmark and Norway practice ovarian tissue cryopreservation as a clinical treatment (822 and 164 cases, respectively) and their programs are centralized. In Sweden (457 cases), ovarian tissue cryopreservation is practiced at five of six centers and in Finland at all five centers (145 cases). Nearly all considered ovarian tissue cryopreservation to be experimental. In Iceland, embryo cryopreservation is the only option for fertility preservation. Most centers use slow-freezing methods for ovarian tissue cryopreservation. Most patients selected for ovarian tissue cryopreservation were newly diagnosed with cancer and the tissue was predominantly retrieved laparoscopically by unilateral oophorectomy. Only minor complications were reported. In total, 46 women have undergone ovarian tissue transplantation aiming at recovering fertility, 17 healthy children have been born and several additional pregnancies are currently ongoing. Whenever patients' clinical condition is permissive, oocyte cryopreservation after hormonal stimulation is preferred for fertility preservation. Between 2012 and 2014, a smaller proportion of females have undergone fertility preservation in the Nordic centers, in comparison to males (1:3).


CONCLUSIONS
Overall, ovarian tissue cryopreservation was reported to be safe. Slow freezing methods are still preferred. Promising results of recovery of fertility have been reported in Nordic countries that have initiated ovarian tissue transplantation procedures.
Reproductive Medicine, Department of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden.|Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden.
Kenny A
http://orcid.org/0000-0003-4378-6181
KA
Rodriguez-Wallberg
Department of Gynecology, Oslo University Hospital, Oslo, Norway.
Tom
T
Tanbo
Tampere University Hospital, Tampere, Finland.
Helena
H
Tinkanen
Sahlgrenska University Hospital, Gothenburg, Sweden.
Ann
A
Thurin-Kjellberg
Linköping University Hospital, Linköping, Sweden.
Elizabeth
E
Nedstrand
Skåne University Hospital, Malmö, Sweden.
Margareta Laczna
ML
Kitlinski
Rigshospitalet University Hospital, Copenhagen, Denmark.
Kirsten T
http://orcid.org/0000-0001-8830-513X
KT
Macklon
Aarhus University Hospital, Aarhus, Denmark.
Erik
E
Ernst
Odense University Hospital, Odense, Denmark.
Jens
J
Fedder
Helsinki University Hospital, Helsinki, Finland.
Aila
A
Tiitinen
Oulu University Hospital and University of Oulu, Oulu, Finland.
Laure
L
Morin-Papunen
ART Medica, Reykjavik, Iceland.
Snorri
S
Einarsson
Turku University Hospital, Turku, Finland.
Varpu
V
Jokimaa
Kuopio University Hospital, Kuopio, Finland.
Maritta
M
Hippeläinen
Örebro University Hospital, Örebro, Sweden.
Mikael
http://orcid.org/0000-0003-3926-5674
M
Lood
Department of Women's and Children's Health, Uppsala University Hospital, Uppsala, Sweden.
Johannes
J
Gudmundsson
Reproductive Medicine, Department of Obstetrics and Gynecology, Karolinska University Hospital, Stockholm, Sweden.|Department of Clinical Science, Intervention and Technology, Division of Obstetrics and Gynecology, Karolinska Institute, Stockholm, Sweden.
Jan I
JI
Olofsson
Rigshospitalet University Hospital, Copenhagen, Denmark.|Laboratory of Reproductive Biology, University of Copenhagen, Copenhagen, Denmark.
Claus Yding
CY
Andersen
D015925:Cryopreservation / Q000706:statistics & numerical data*; D004622:Embryo, Mammalian; D005260:Female; D059247:Fertility Preservation / Q000379:methods* / Q000706:statistics & numerical data; D006785:Hospitals, University; D006801:Humans; D009865:Oocytes / Q000637:transplantation; D010053:Ovary / Q000637:transplantation; D012537:Scandinavian and Nordic Countries; D011795:Surveys and Questionnaires
Cancer; female; fertility preservation; oocytes; ovarian tissue cryopreservation; ovarian transplantation