uterus

The uterus, also known as the womb, is a muscular organ in the female pelvis where fetal development occurs. It is located between the bladder and the rectum and is connected to the ovaries by the fallopian tubes. The uterus plays a central role in reproduction by supporting implantation of a fertilized egg and sustaining pregnancy.

Anatomy and structure: The uterus has three regions—the fundus at the top, the body (corpus) in the middle, and the cervix at the lower end that opens into the vagina. Its wall comprises three layers: the outer perimetrium (serosa), the thick middle myometrium made of smooth muscle, and the inner endometrium, which thickens during the menstrual cycle and temporarily supports implantation. The uterus is supplied mainly by the uterine arteries, branches of the internal iliac arteries, with venous drainage through uterine veins.

Position and development: In adults, the uterus is typically anteverted and anteflexed within the pelvis. It develops from the Müllerian ducts during embryogenesis, and congenital anomalies can alter size or shape. Uterine size and tone vary with age, hormonal status, and pregnancy.

Function: The endometrium responds to cyclic hormones by thickening to prepare for possible implantation and shedding during menstruation if pregnancy does not occur. During pregnancy, the uterus expands substantially to accommodate the developing fetus, and uterine contractions help initiate labor at term.

Clinical relevance: Common uterine conditions include fibroids (leiomyomas) in the myometrium, adenomyosis, and, less commonly, endometriosis involving the endometrium. Congenital anomalies such as septate or bicornuate uteri, and uterine cancers (notably endometrial cancer), are also recognized. Diagnosis typically involves gynecologic examination and imaging.