The cardinal ligament (Mackenrodt ligament, transverse cervical ligament, parametrium) is the most important structural support of the uterus and upper vagina, running from the cervix and upper vagina laterally to the pelvic sidewall and the fascia over the obturator internus. It contains the uterine artery and its branches, the venous plexus of the parametrium, and the autonomic nerve fibres of the inferior hypogastric plexus. The ureter runs through the parametrium within the cardinal ligament just before crossing under the uterine artery.
The primary lateral support structure of the uterus and vaginal apex, preventing uterine prolapse and maintaining cervical position. Contains the main uterine blood supply and is the barrier crossed by uterine cancer in lateral spread.
The cardinal ligament is the critical structure in radical hysterectomy (Wertheim hysterectomy) for cervical cancer, where resecting the parametrium is the key oncological step to achieve tumour-free margins. The ureter running through the cardinal ligament must be identified and protected throughout parametrial dissection. In hysteroscopic and laparoscopic hysterectomy, the uterine artery at the cardinal ligament level is the primary vascular pedicle. In sacrocolpopexy for vault prolapse, mesh must be attached inferiorly at the cardinal ligament level to adequately support the upper vagina.
The ureter passes through the parametrium within the cardinal ligament approximately 1-2 cm lateral to the cervix and crosses under the uterine artery here; division of the cardinal ligament in hysterectomy without visualising the ureter risks thermal injury or ligation of the ureter, the most common serious complication of hysterectomy.
