The uterus and common uterine problems
Where do children come from? All parents eventually get this question. There are many different ways to explain the complicated process of forming of a new life to a child, but our answer is a short and precise—children come from the uterus.
No other organ in the human body as flexible and changeable as the uterus! Over the course of a pregnancy it can expand from the size of a large plum to the size of a watermelon, and then return to normal after childbirth.
The uterus, or womb, is part of the female reproductive system—unique to women. This hollow organ lies within the pelvis, shaped like an upside-down pear.
Structure and position
The uterus is a thick-walled organ that is especially stretchy and muscular. This is where the foetus (developing baby) grows when a woman’s egg is fertilized by a man’s sperm and implants itself into the uterine wall.
The uterus lies between the urinary bladder in the front and the sigmoid colon in the back.
The body of the uterus (corpus uteri) includes:
- the fundus—situated above the point where the fallopian tubes enter the uterus
- the uterine cavity—the hollow in which the foetus develops
- the isthmus—a narrowing at the base of the uterus
The uterine wall is made up of three layers:
- the perimetrium, or outer layer of the uterus, envelops the body of the uterus and part of the cervix (2mm thick)
- the myometrium, or intermediate layer, consists of smooth muscle fibres arranged in longitudinal, circular, and spiral patterns, and connective tissue (15mm)
- the endometrium, or inner lining of the uterus, is made of mucosal tissue (6 to 16 mm, depending on the stage of the menstrual cycle)
The cervix also has several named parts:
- The endocervix or endocervical canal is the passage that connects the uterus to the vagina
- The internal os is the opening in the middle of cervix that leads to the uterus
- The ectocervix is the passage between the uterus and vagina
- The external os or cervical canal is the space in the centre of the ectocervix
If no fertilized egg has implanted in the uterine wall, each month the endometrium breaks down and is expelled from the body as period secretions and fresh new layer begins to form.
The uterus has three main functions that support the development of a baby:
- it protects the foetus from physical damage
- it provides nutritional support so that the foetus can develop properly
- it manages waste removal, keeping the space around the foetus clean
The uterus during pregnancy
The uterus grows dramatically during pregnancy. During the first trimester, the uterus reaches the size of a grapefruit and fits within the pelvis.
In the second trimester, the uterus grows to about the size of a papaya and no longer fits in the pelvis—the top edge reaches to about midway between the navel and the breasts.
As the uterus grows, it displaces the other internal organs and puts strain on the surrounding muscles and ligaments. This can cause some minor aches and pains, but they are completely normal.
The growing uterus also presses on blood vessels, causing some women’s legs to swell, puts pressure on the bladder, making it necessary to urinate more often, and presses on the respiratory system and heart, encumbering breathing and movement.
If a woman is carrying twins or multiples, the uterus will stretch and grow more quickly.
During the third trimester, the uterus grows to about the size of a watermelon. At full term—when the baby is fully developed—the uterus extends all the way from the pubic area to the rib cage. As the body prepares to give birth, the baby settles lower into the pelvis and the cervix begins to dilate so the uterine muscles can push the babe out into the world.
After birth, the uterus will gradually to the size, shape, and position it had before pregnancy. This is called involution and usually takes about 6 weeks.
Common uterine problems
Many medical conditions can affect the womb, such as polyps, endometriosis, fibroids, or cancer. Some cause pain and discomfort that is usually felt in the pelvic area and lower abdomen. More severe pain radiates to the middle of the abdomen or lower back. Other symptoms associated with various uterine problems include irregular periods and difficulty getting pregnant. If you experience any of these symptoms it is important to see a doctor for diagnosis because some concerns are quite serious, while others tend to resolve themselves.
A retroverted uterus—also called a tipped uterus, tilted uterus, or retroflexed uterus—is a uterus that curves in a backward instead of forward from the cervix. About 1 in 4 women has a tilted uterus.
In the past, doctors thought that having a retroverted uterus contributed to infertility, but we now know that the position of the uterus doesn’t interfere with sperm reaching the egg.
Occasionally, scar tissue can form from endometriosis, infection, or prior surgery, tilting the uterus more sharply. Although this may make it more challenging for the sperm to reach the egg, it should still be possible to conceive. However, in such cases it may be helpful to consult a fertility specialist.
Fibroids
A fibroid is a non-cancerous growth, or local thickening of the myometrium. Fibroids often cause abundant menstrual bleeding.
There are three main types of fibroids:
- Subserosal fibroids form on the surface of the uterus. If they grow large and cause discomfort, they can be removed surgically.
- Intramural fibroids grow within the muscular uterine wall and can be detected by ultrasound. The often cause an increase in the volume of menstrual fluids. Like most fibroids, intramural fibroids tend to regress after menopause.
- Submucosal fibroids develop just beneath the endometrium and are usually only 1 to 1.5 centimetres in diameter. Despite their small size, they can cause heavy bleeding and bleeding between periods as the tissue just beneath the endometrium is haemorrhagic—or liable to bleed profusely. Submucosal fibroids are treated with medicine but can be removed surgically if necessary.
Polyps
These are usually small, benign tumours, but they can cause intermenstrual bleeding, abnormal bleeding, or bleeding after menopause. You can have one or multiple uterine polyps. Polyps often occur in perimenopausal women because the endometrium no longer renews itself regularly each month. They usually remain within the uterus, but occasionally can slip down through the cervix into the vagina. Small, asymptomatic polyps often resolve on their own.
If the polyps grow larger and cause problems, medication can provide a short-term solution but surgical removal is more effective.
Endometrial hyperplasia is abnormal thickening of the endometrium. Hyperplasia can be the result of a temporary hormonal imbalance but can also indicate a pre-cancerous state.
Symptoms of endometrial hyperplasia include abnormal bleeding between periods or more heavy periods. Excessive weight and obesity are risk factors for hyperplasia and its progression to endometrial cancer. The fatty mass manufactures an excess of oestrogens in comparison to progesterone levels. This hormonal imbalance stimulates an overproduction of uterine lining. Women who tend to be overweight or obese can regularly undergo vaginal ultrasounds to monitor this condition.
Endometriosis is a chronic inflammatory disease characterized by the development of uterine lining outside the uterus. Adenomyosis is when endometriosis develops within the uterine muscles. This causes aggravated dysmenorrhea—abundant and painful periods that get worse from month to month. Endometriosis affects approximately one in 10 women of childbearing age and can start as early as puberty.
What to do? Doctors often prescribe oral contraceptives, which interrupt the menstrual cycle, allowing the uterus to rest, which can ease the symptoms. Please remember that some period pain is normal. If you have any questions about what you are experiencing don’t hesitate to discuss them with your doctor or gynaecologist.
Cervical cancer is now a preventable disease. A vaccine against the human papillomavirus (HPV), which is present in most cancerous cervical cells, was developed in the 1990s and is now broadly available. The Papanicolaou test or Pap smear, in which a small number of cells are taken from the cervix, can detect cellular alterations linked to an HPV infection. Such alterations are called dysplasia, and do not cause any discomfort or symptoms. Regular pap smears (once every three years) are the best way of detecting dysplasia.
It is also important to know that dysplasia doesn’t transform in cancer in a single day. It takes years for this to happen. Visit your gynaecologist regularly to detect and prevent unwanted changes.
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