Our research team, led by gynaecologist Mr Richard Smith, has performed a series of interlinked procedures over more than 20 years related to womb transplantation.
This work represents the background of research into uterine blood supply as well as other anatomical considerations. Originally, the group believed falsely that 4 of the following 6 blood vessels (2 uterine, 2 ovarian and also a collateral supply from 2 vaginal vessels) were necessary to maintain a viable uterus. Subsequent studies showed that the uterus remains viable when supplied by ovarian vessels alone and is capable of pregnancy and delivery.
In view of the team’s original concept that 4 vessels were required for uterine survival, they operated on pigs to investigate whether first dividing and then re-connecting uterine arteries would lead to subsequent normal function during pregnancy. A ‘microvascular technique’ for uterine autotransplantation was developed and used in 8 pigs which underwent uterine transplantation. This technique proved unsuccessful as those subjects that survived the initial post-operative period failed to achieve a normal menstrual cycle (suggestive of adequate fertility). Post-mortem examinations revealed thrombosis i.e. malfunction of the small uterine blood vessels.
To overcome this, a large vessel patch technique or ‘macrovascular’ technique, which solved a similar problem in the transplantation of the small bowel, was subsequently utilized with limited success in a preserved human cadaver and freshly killed pigs and rabbits. The study involved taking part of the aorta, inferior vena cava, common and internal iliac vessels coupled with the uterine arterio-venous tree, together with the uterus en bloc as a large vessel patch. This ‘method’ was supported by evidence demonstrating that the uterus resected en bloc is probably less likely to undergo blood vessel thrombosis.
The technique was subsequently applied to cross-transplant 22 rabbits (11 donors and 11 recipients) in 2 separate experiments. In the first experiment, our 6 rabbit recipients surgically survived the procedure. After post-mortem and histological analyses in the short term, all of the wombs appeared viable with no evidence of graft vessel thromboses. The complications experienced postoperatively were not related to the actual surgical techniques employed during transplantation.
The second experiment, most likely because of better understanding and greater experience in the necessary surgical techniques, revealed much better outcomes with all 5 rabbits surviving in the immediate post-operative period. Two rabbits demonstrated long-term survival (9 and 11 months respectively) and a healthy, viable womb during post-mortem. The team has now achieved successful uterine cross-transplantation in rabbits. In addition, the large vessel patch technique has demonstrated its feasibility in humans with regards to anatomy. An allied team in New York, consisting of gynaecologic oncology trained surgeons familiar with pelvic side wall dissection, has used the technique with success in using organs from local donor networks using existing protocols.