Ligaments Supporting the Uterus
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Direct answer
The uterus is held by four main ligaments, the cardinal, uterosacral, round and broad, with the pelvic floor adding support. The cardinal ligament is the main lateral support of the cervix, and the uterosacral ligaments are the main posterior support that keeps the cervix and vault up. The round ligament mainly keeps the uterus anteverted, while the broad ligament is a peritoneal fold that carries vessels, the tube and the ovary. Laxity of the cardinal and uterosacral ligaments is a major cause of uterine and vault prolapse.
What you must remember
- Cardinal ligament: runs from the lateral cervix and upper vagina to the lateral pelvic wall, and contains the uterine artery; it is the key structure divided in radical hysterectomy.
- Uterosacral ligament: runs from the posterior cervix and upper vagina to the sacrum, roughly at the level of S2 to S4, and carries autonomic nerve fibres from the inferior hypogastric plexus, with the ureter lying lateral to it.
- Round ligament: arises from the cornu of the uterus, passes through the inguinal canal and ends in the labia majora; it keeps the uterus anteverted.
- Broad ligament: a double peritoneal fold from the uterus to the pelvic side wall containing the fallopian tube, the ovary's mesovarium, the round ligament and the uterine vessels.
- Ovarian ligament: links the medial pole of the ovary to the cornu of the uterus, and is distinct from the suspensory ligament, which carries the ovarian vessels to the pelvic brim.
- Pelvic floor: levator ani supports the whole pelvic organ complex and is the secondary defence when the ligaments give way.
- Clinical consequence: laxity or damage to the cardinal and uterosacral ligaments produces uterine and vault prolapse, and a patent processus vaginalis along the round ligament forms a canal of Nuck hydrocele or hernia.
A worked case of uterine descent
Consider a 58-year-old multiparous woman with a sense of a bulge at the introitus and second-degree uterine descent on examination. Her cervix descends to the level of the introitus when she strains, and the clinical question is which support has failed.
- Identify the failed support. The uterosacral and cardinal ligaments are the primary apical supports, and their laxity lets the cervix and vault drop, while the levator ani may be stretched by vaginal delivery.
- Examine every compartment. A cystocele or enterocele may coexist, so the examination should assess the anterior and posterior compartments as well.
- Choose vaginal hysterectomy when suitable. Vaginal hysterectomy is often chosen when the uterus is descended and the operator is experienced. During the procedure the uterosacral ligaments are plicated to suspend the vault, which restores apical support.
- Preserve the uterus when wanted. When the uterus is preserved, a sacrospinous fixation or uterosacral suspension achieves the same aim.
- Skip round ligament surgery for prolapse. The round ligament is not a major support of the vault, and its role is largely in anteversion and in canal of Nuck pathology.
Where the exam tries to catch you
Ligament questions usually turn on which structure runs where.
- Trap: confusing the cardinal with the uterosacral ligament. Correct: the cardinal ligament runs laterally to the pelvic side wall, while the uterosacral ligament runs back toward the sacrum, and examiners ask about each in separate contexts.
- Trap: calling the broad ligament the main uterine support. Correct: it is a double layer of peritoneum that carries the tube, the mesovarium, the round ligament and the vessels, not a true supporting ligament.
- Trap: mixing up the round and ovarian ligaments. Correct: the round ligament runs through the inguinal canal to the labia majora, whereas the ovarian ligament stays within the pelvis.
An inguinal swelling after pregnancy may point to round ligament or canal of Nuck pathology rather than a standard hernia.
Frequently asked questions
Which ligament is divided during radical hysterectomy?
The cardinal ligament is divided during radical hysterectomy, because it lies between the cervix and the pelvic side wall and contains the uterine artery. Division of this ligament gives access to the parametrium for resection.
What is the main posterior support of the uterus?
The uterosacral ligaments are the main posterior support of the uterus and vault, running from the posterior cervix to the sacrum at about S2 to S4. Their laxity is a common cause of posterior and apical prolapse.
What does the round ligament do?
The round ligament keeps the uterus anteverted and runs through the inguinal canal to the labia majora. A patent processus vaginalis along this ligament can form a canal of Nuck hydrocele or hernia, and the ligament is not a main support in prolapse.
Is the broad ligament a true ligament?
The broad ligament is not a true ligament but a double fold of peritoneum that extends from the uterus to the pelvic side wall. It contains the fallopian tube, the mesovarium, the round ligament and the uterine vessels.