Anatomy, Abdomen and Pelvis, Uterus

The uterus is a hollow, pear-shaped organ that is responsible for a variety of functions such as gestation (pregnancy), menstruation, and labor and delivery. On a coronal cut section, its cavity has an inverted triangle shape. Sometimes the development in utero may be incomplete; this is called a Mullerian anomaly and can lead to many variants, ranging from a uterine septum to uterine didelphys (double uterus). Anatomically, the uterus is located in the female pelvis immediately posterior to the bladder and anterior to the rectum. The female uterus subdivides into four main anatomic segments (from superior to inferior): the fundus; a broad curved area in which fallopian tubes connects to the uterus, corpus (body); the main part of a uterus and it starts directly below the level of fallopian tubes and continues downward, isthmus; a lower neck region of the uterus, and cervix; which extends downwards from the isthmus and opens in the vagina.Several ligaments support the uterus, including the utero-ovarian ligament, round ligament, broad ligament, cardinal ligament, and uterosacral ligaments. It is further supported (inferiorly) by the pelvic diaphragm, urogenital diaphragm, and perineal body. The uterus may naturally lie in different positions such as anteverted/retroverted, anteflexed/retroflexed, or midline, and it may be rotated (especially during pregnancy). The uterus most commonly lies in an anteflexed and anteverted position in 50% of women.When the uterus is in a retroverted/retroflexed or tipped position, it may cause pelvic pain, dyspareunia, minor incontinence, fertility difficulty, and difficulty inserting tampons. In pregnancy, this may lead to uterine incarceration.