Uterus

Function

The uterus is a pear-shaped muscular chamber that can enlarge its capacity roughly 500–1,000-fold — from 60 g and 7 cm in the non-pregnant state to a 1 kg, 30 cm organ housing a full-term infant. Its three-layered myometrium weaves spirally so that postpartum contraction clamps the vessels running through it — the 'living ligatures' that prevents haemorrhage.

The endometrium renews itself monthly under oestrogen's build and progesterone's ripening, shedding as menstruation when the corpus luteum retires. Its position — anteverted and anteflexed over the bladder — is maintained by the round, broad, uterosacral and cardinal ligaments, the latter the surgical anchor of pelvic support.

Blood supply

Uterine artery from the internal iliac — crossing the ureter 'water under the bridge'; ovarian arteries from the aorta.

Nerve supply

Parasympathetic S2–S4 (pelvic splanchnic), sympathetic T10–L1; labour pain travels T10–L1 then S2–S4 in the second stage.

Clinical relevance

Fibroids (leiomyoma)

The commonest tumour of women — oestrogen-fed smooth muscle nodules causing heavy periods, bulk symptoms and infertility.

Endometrial cancer

Postmenopausal bleeding is its herald — caught early, surgery is usually curative.

Prolapse

Childbirth's toll on the cardinal-uterosacral complex lets the uterus descend toward the vagina.

Related conditions

• Endometriosis
• Uterine fibroids
• Cervical cancer
• Endometrial (womb) cancer
• Pelvic inflammatory disease
• Pre-eclampsia