Livebirth and utero-placental insufficiency in Papio hamadryas baboons with uterus angiosome perfused by bilateral utero-ovarian microsurgical anastomoses alone

Study question: Can the baboon uterus support a gestation to livebirth with an angiosome using microsurgically anastomosed utero-ovarian vessels and lacking uterine arteries and veins?

Summary answer: Our angiosome model allows healthy livebirth albeit with risk of fetal growth restriction and stillbirth.

What is known already: Uterine transplant can provide livebirth in humans, but requires a living donor to undergo a prolonged laparotomy for hysterectomy. In an attempt to avoid the time-consuming dissection of the uterine vein, our group has previously shown maintenance of baboon uterine menstrual function after ligation of the uterine vein and after ligation of both the uterine artery and uterine vein.

Study design, size, duration: In a 19-month timespan, three baboons underwent laparotomy to surgically alter uterine perfusion, and pregnancy outcomes were monitored after spontaneous mating in a breeding colony.

Participants/materials, setting, methods: Three nulligravid female Papio hamadryas baboons in a breeding colony underwent laparotomy to ligate uterine arteries and veins along with colpotomy and cervico-vaginal anastomosis. During the same surgery, the utero-ovarian arteries and veins were microsurgically transected and re-anastomosed to themselves. Intraoperative organ perfusion was confirmed with laser angiography. After a recovery period, monitoring of menstrual cycling via menstrual blood flow and sex-skin cycling occurred, as well as uterine viability via sonography and cervical biopsy. Each baboon was released to the breeding colony for spontaneous mating and pregnancies dated by menstrual calendar and compared with early ultrasound. Delivery outcomes were monitored in each including neonate weight and placental pathology. In the event of a stillbirth, the animal was returned to the breeding colony for repeat mating attempts. After achieving a livebirth, the maternal baboon was removed from the study.

Main results and the role of chance: Each baboon in the trial underwent successful surgery with all uteri demonstrating viability and return of menstrual function within 10 weeks of surgery. Pregnancies occurred within two menstrual cycles in breeding colony. Baboons one and two initially had vaginal breech stillbirths, both with appearance of placental insufficiency, and one with fetal growth restriction. Baboon three underwent scheduled cesarean delivery resulting in a normally grown livebirth. Baboon one had a subsequent pregnancy resulting in a livebirth via cesarean delivery.

Limitations, reasons for caution: Stillbirth in two of four gestations, and fetal growth restriction in one of four, are the largest concerns in our perfusion model. It remains uncertain whether the stillbirths resulted from placental insufficiency, or birth trauma from breech deliveries.

Wider implications of the findings: The success of two livebirths warrants further attempts at improving consistency of our proposed uterine angiosome. This may allow living uterine donors to undergo less-invasive and shorter donor hysterectomy procedures.

Study funding/competing interest(s): The study had no external sponsors, and was supported by the Cleveland Clinic Foundation. Some equipment was loaned without cost to the research team including a laser angiography system courtesy of Novadaq Technologies, Inc. (Missaugua, ON, Canada) and a surgical microscope courtesy of DB Surgical (Coral Springs, FL, USA). B.B., K.A., M.S., K.R., M.M., P.F.E., A.T. and T.F. have no conflicts of interest. M.L.S. and S.Z. report activity as consultants for Medtronic-Covidien, and S.Z. also is a consultant to Applied Medical.