Indocyanine green fluorescence imaging in the pregnant cynomolgus macaque: childbearing is supported by a unilateral uterine artery and vein alone?

Purpose Uterine blood flow is required for the maintenance of uterine viability in pregnancy and delivery, but it is unknown how many vessels are necessary for maintenance of uterine viability. The objective of this study was to examine whether unilateral uterine vessels provide sufficient nutrition in pregnancy in a cynomolgus macaque and to evaluate hemodynamics of pregnant uterus by indocyanine green (ICG) fluorescence imaging. Methods A cynomolgus macaque with uterine blood flow maintained by the right uterine artery and vein alone was made pregnant. Hemodynamics of the uterus in the third trimester was evaluated by ICG fluorescence imaging. Results Pregnancy was maintained with the right uterine artery and vein. An appropriate-for-date infant was delivered by Cesarean section. ICG fluorescence imaging showed that the uterine body was imaged from the right side to the center; furthermore, collateral circulation was present from the right uterine artery toward the left uterine artery, with expanded blood flow to the left uterine body. Conclusion Pregnancy and delivery were achieved in a cynomolgus macaque with a unilateral right uterine artery and vein. Blood flow to the side without the artery was complemented by vascularization of collateral circulation to the uterine artery.