Theuterus is an essential part of thefemale reproductive system. It is within the uterus that the fetus will develop and remain protected throughout pregnancy. As each woman is unique, the morphology of the womb varies. But what are the different shapes of the uterus? Here's everything you need to know.
Understanding the uterus before knowing its shape
Before examining the different shapes of the uterus, we'd like to take a look at the anatomical definition of this reproductive organ and its formation.
What is a uterus?
Located between the bladder and the rectum, theuterus is a hollow muscular organ belonging to the female reproductive system. It measures 7 to 8 cm in length and is triangular in shape, resembling an inverted pear. It consists of three parts:
- The uterine fundus (the uppermost area from which the Fallopian tubes extend) ;
- The body (the largest part where theembryo can implant) ;
- The cervix (narrow, constricted area leading to the vagina).
Theuterus is also lined with a thick wall made up of three layers:
- Theendometrium or uterine mucosa (an internal layer rich in blood vessels that is renewed during the periods) ;
- The myometrium (intermediate layer composed mainly of smooth muscle) ;
- The perimetrium (outer serous layer covering the body of the luterus and part of the cervix).
How is a woman's uterus formed? l
The humanreproductive system is established during embryonic development. Until the 6th week, it remains undifferentiated. If the fetus is female, it will not secrete anti-mullerian hormone (AMH). The uterus therefore begins to form from the7th week, duringorganogenesis. This reproductive organ develops in three phases:
- Migration of the Müllerian ducts towards the urogenital sinus (between weeks 6 and 9);
- The lower part of these ducts come together to form the uterine cavity (separated in two by an intermüllerian septum) and the upper two-thirds of the vagina (between the 9th and 13th weeks);
- Resorption (disappearance) of the inter-mullerian septum completing the formation of the female uterus (between the 13th and 17th weeks).
What are the different shapes of the uterus?
There are different shapes of uterus. Gynecologists have given them names referring to their position : straight, anteverted or retroverted. Many women have matrices of this type. These particular uterine morphologies are not systematically detected during medical examinations, and generally do not cause any problems.
A straight uterus is a female organ that is well aligned with the vagina. This is an ideal anatomical position, and a rare one, since nothing in nature is perfectly symmetrical. This shape greatly facilitates penetration, childbirth and IUD insertion.
Most women have an anteverted uterus. This is the most common form. It is tilted forward at the cervix and rests on the bladder. This condition is completely normal and usually has no effect on sexual relations or the progress of a pregnancy.
There are two anatomical variants of this type of matrix:
- The anteverted anteflexed uterus (the axis between the cervix and the uterine body forms an open angle towards the front);
- The uterus is anteverted and retroflexed (the axis between the cervix and the uterine body forms an open angle towards the rear).
Extreme anteflexion can lead to urinary difficulties during the first trimester of pregnancy. An overly retroflexed anteverted uterus can cause painful periods (dysmenorrhoea) and discomfort in certain sexual positions(dyspareunia). But rest assured, these phenomena are very rare.
A retroverted uterus corresponds to a female organ inclined towards the back of the body and resting on the rectum. This physical characteristic occurs in 20-30% of women. It generally causes no particular symptoms and has no impact on fertility.
However, a retroverted uterus can sometimes cause pain during periods, intercourse and defecation, as well as constipation and frequent urination.
What are uterine malformations?
Uterine malformations affect between 3% and 4% of women*. They result from a defect or arrested development of the female genital tra ct during organogenesis. While most are asymptomatic, some can impair fertility and lead to miscarriage.
Also known as the double uterus, thedidelphic uterus results from non-fusion of the Müllerian ducts. It affects 5% of matrix dysmorphoses*. Women with this congenital anomaly have two independent uterine cavities. There are two types of didelphic uterus:
- Bicervical (two uterine cavities and two vaginas);
- Unicervical (two uterine cavities and a single vagina).
This form generally does not affect reproductive capacity. It can, however, lead to complications such as repeated miscarriages and premature deliveries.
Often confused with the didelphic uterus, thebicornuate uterus is characterized by a double V-shaped uterus. This malformation is the result of incomplete fusion of the Müllerian ducts. It is also known as a heart-shaped uterus. This is because it creates a more or less large cleft in the upper part of the womb. Two subtypes have been identified by the medical profession:
- Complete bicorne (the cleft touches the external or internal cervical opening);
- Partial bicorn (the scleft extends only inside l l the uterus).
Women with a bicornuate uterus have reduced uterine space. In the event of pregnancy, this can delay fetal development and increase the risk of miscarriage or premature birth. Conversely, lunicornuate uterus when the uterus has only one Fallopian tube.
A septate uterus is the most common congenital malformation. Its prevalence sis 55%. The uterine cavity is abnormally separated by a median septum. This wall may occupy half or all of lthe organ.
The complications caused by a septate uterus are much the same as those previously mentioned for a bicornuate uterus. However, it is possible to resort to surgery to remove this wall in order to reduce the rate of miscarriage and increase the chances of pregnancy.
Uterine hypoplasia: small uterus
Uterine hypoplasia or infantile womb refers to insufficient development of the uterus, most often caused by a fetal malformation or an episode of malnutrition in the infant. An adult woman's uterus is generally 7 to 8 cm long. A hypoplastic uterus will not exceed 5 cm in length.
There are two types of small uterus: thefetal uterus and theinfant or adolescent uterus. The fetal uterus is an organ that stops growing immediately after birth. It therefore measures no more than 4 cm. Women with embryonic hypoplasia suffer from amenorrhea and infertility.
The second refers to a matrix whose growth sstops during infancy. Its maximum length will be 5 cm. Pregnancy remains possible, but will be considered high-risk due to the high probability of spontaneous abortion and premature delivery.
Uterovaginal aplasia: absence of uterus and part of vagina
Uterovaginal aplasia is a rare congenital anomaly resulting in theabsence of the uterus and the upper two-thirds of the vagina. This malformation is also known as MRKH (Mayer-Rokitansky-Kuster-Hauser) syndrome. It affects 1 in 4500 female children.
Girls with this syndrome have functional ovaries and normal external genitalia. However, they frequently suffer from a lack of periods and have difficulty during intercourse.
What about the contractile uterus?
The termcontractile uterus"does not refer to a malformation of this organ. Rather, it refers to a dysfunction that occurs during pregnancy. A pregnant woman's uterus contracts abnormally and repeatedly (more than 10 times a day). These uterine contractions can appear from the 4th month of gestation and last between 30 seconds and 1 minute.
Whether they are painful or not, it is important to consult a health professional as soon as possible. A contractile uterus can cause the cervix to open, leading to miscarriage or premature delivery.
How can I be diagnosed with a certain type of uterus?
Many women are unaware of the shape of their uterus. Some types, such asanteverted or retroverted, are so common that they usually go unnoticed during a gynaecological examination. Even more so if the patient has no significant symptoms. A midwife or gynaecologist can, however, identify a certain shape of uterus by a simple vaginal touch or by examining the cervix after inserting a speculum.
A uterine malformation does not systematically imply amenorrhea or fertility problems. Some women with a bicornuate uterus, for example, have perfectly normal pregnancies and only discover this morphological feature during the course of their pregnancy.
On the other hand, if you suffer from a lack of periods, intense pain during periods or if you have difficulty getting pregnant, make an appointment with a health professional for a check-up.
To diagnose a uterine anomaly, a medical imaging examination is required. Ultrasound, hysteroscopy (exploration of the uterine cavity through a hysteroscope) or hysterography (X-ray of the luterus) can detect any malformation and enable rapid treatment.
FAQs on the different types of uterus
What is the normal shape of the uterus?
Most women have an anteverted uterus (tilted forward l). Some, however, may have a retroverted uterus (tilted backwards l). Both forms are perfectly normal.
Is it serious to have a small uterus?
It all depends on the degree of uterine hypoplasia. If the uterus measures no more than 4 cm, it will result in the absence of periods and infertility. On the other hand, if it measures 5 cm, pregnancy is quite possible. However, it must be carefully monitored, as it is considered a high-risk procedure.
When should you consult a doctor about your uterus?
If you're suffering from amenorrhea, your periods are very painful or you're unable to get pregnant, consult your gynecologist or midwife without delay to have your uterus examined.