Normal Uterus

Normal Uterus
The uterus is a inverted pear shaped muscular organ located in the middle of the female pelvis, between the bladder and the rectum. It is suspended by ligaments in the abdominal cavity. It is basically made up of three parts: the cervix, which is the lowest portion attached to the vaginal canal, and the main body of the uterus, the central part of the organ and the upper area known as the fundas or dome. The average adult uterus is approximately 3″L x 2″W x 1″D. This varies depending on the number of pregnancies: the greater the number the larger the uterus. After menopause, the uterus will shrink to near pre-pregnancy size.

The uterus is composed of two distinct anatomical areas: myometrium and the endometrium which lines the cavity. The endometrium is the innermost layer of the uterus that contains the lining which is responsible for accepting and nourishing a fetus during the pregnancy process. The lining of this cavity changes with every monthly cycle in response to the primary female hormones produced by the ovaries: estrogen and progesterone.  As a women starts her cycle every month, estrogen increases and the endometrial lining thickens in preparation for the fertilized egg. If a fertilized egg is not detected, estrogen drops and the lining is sluffed off. This is your monthly menstrual cycle. In the average woman, this occurs every 28 days and lasts for 3-7 days. Variations in these numbers do exist. The thickness of this endometrial lining can be greatly effected by certain conditions like fibroid tumors, adenomyosis and hormone imbalance. The myometrium is the smooth muscle layer of the uterus. This is where contractions occur during the active delivery process, and where most fibroids develop.

Adjacent to the uterus on either side are the ovaries. Both ovaries have the primary function of releasing hormones into the body, and releasing a ripened egg into the fallopian tube at approximately the 14th day of the womans cycle. Each female is born with a specific number of eggs that will be released for possible pregnancy. These eggs travel down to the uterus through the fallopian tubes and are released into the endometrial cavity. Only one egg is normally dispensed with every cycle, and the ovaries alternate this function every month. The life cycle continues on average for approximately 50 years. As a woman reaches her late 40s-early 50s the ovaries begin to slow down and less hormone is produced. This is known as the peri-menopausal phase. Cycles become less in number and shorter in days. A woman will begin to experience physiological changes like hot flashes, sleeplessness, dry vaginal vault, headaches, difficulty concentrating and sometimes depression. Once in menopause, many physicians will recommend some type of hormone replacement therapy (HRT) to supplement diminishing hormone levels. Although, this can be a very necessary therapy, it can greatly effect certain diseases like fibroids, adenomyosis, endometriosis and ovarian cysts and is contra-indicated for malignant diagnoses like uterine, cervical, ovarian and breast cancers.

Keep in mind, the above discussion focused on anatomy “within normal limits”. Once a specific pathology, like fibroids or adenomyosis, has invaded an organ, changes begin to occur. Symptoms will vary, depending on the patient, and the severity of the disease.