All about the different types of uterus
Theuterus is an essential organ of thefemale reproductive system. Indeed, it is within it that the fetus will be able to develop and remain protected throughout the pregnancy. Each woman being unique, the morphology of this matrix remains variable. But what are the different shapes of the uterus? Here is everything you need to know.
Understanding the uterus before knowing its shape
Before examining the different shapes of the uterus, we suggest that you review the anatomical definition of this reproductive organ as well as 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 is 7 to 8 cm long and has a triangular shape, similar to an upside-down pear. It consists of three parts:
- The uterine fundus (the highest area from which the fallopian tubes extend) ;
- The body (the largest part where theembryo can implant);
- The cervix (the narrow, constricted area leading to the vagina).
Theuterus is also lined with a thick wall made up of three layers:
- Theendometrium or uterine mucosa (inner layer rich in blood vessels that is renewed during menstruation);
- The myometrium (intermediate layer mainly composed of smooth muscles);
- The perimetrium (outer serous layer covering the body of the uterus and part of the cervix).
How is the female uterus formed?
The humanreproductive system is formed during embryonic development. Until the 6th week, it remains undifferentiated. If the fetus is female, it will not secrete anti-Müllerian hormone (AMH). Its uterus will therefore begin to form from the7th week, duringorganogenesis. This reproductive organ develops in three phases:
- Migration of the Müllerian ducts towards the urogenital sinus (between the 6th and 9th week);
- Accoulement of the lower part of these ducts creating the uterine cavity (separated in two by an inter-müllerian partition) and the two upper thirds of the vagina (between the 9th and the 13th week);
- Resorption (disappearance) of the intermüllerian septum completing the formation of the female uterus (between the 13th and 17th week).
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 these types of matrices. These particular morphologies of the uterus 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 quite rare, as nothing is perfectly symmetrical in nature. This shape greatly facilitates penetration, childbirth and IUD insertion.
Most women have an anteverted uterus. This is the most common shape. It is tilted forward at the cervix and rests on the bladder. This condition is completely normal and most often does not affect sexual intercourse or the progress of a pregnancy.
There are two anatomical variations of this type of matrix:
- The anteverted anteflexed uterus (the axis between the cervix and the uterine body forms an open forward angle);
- Retroflexed anteverted uterus (the axis between the cervix and the uterine body forms an open angle towards the back).
Extreme anteflexion can cause urinary difficulties during the first trimester of pregnancy. An anteverted uterus that is too retroflexed can cause painful menstruation(dysmenorrhea) and discomfort during certain sexual positions(dyspareunia). But rest assured, these phenomena remain very rare.
A retroverted uterus is a female organ that is inclined towards the back of the body and rests on the rectum. This physical characteristic occurs in 20 to 30% of women. It does not usually cause any particular symptoms and does not affect fertility.
However, a retroverted uterus can cause pain during menstruation, sexual 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 a stop in the development of the female genital tract during organogenesis. While most are asymptomatic, some can reduce fertility and lead to miscarriage.
Also known as a double uterus, thedidelphic uterus results from the non-fusion of the Müllerian ducts. It affects 5% of matricial 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 one vagina).
This form generally does not alter reproductive capacities. However, it can lead to various complications such as repeated miscarriages or premature deliveries.
Often confused with the didelphic uterus, thebicornuate uterus is characterized by a double V-shape. This malformation is the result of an incomplete fusion of the Müllerian ducts. It is also called 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 bicorn (the cleft affects the external or internal cervical opening);
- Partial bicorn (the cleft extends only into the uterus).
Women with a bicornuate uterus have a reduced uterine space. In the event of pregnancy, the development of the fetus may be delayed and the risk of miscarriage or premature birth is greater. Conversely, we speak of aunicornuate uterus when the uterus has only one fallopian tube.
A septate uterus is the most common congenital malformation. Its prevalence is 55%. The uterine cavity is abnormally separated by a median wall. This wall may occupy half of the organ or all of it.
The complications caused by a septate uterus are essentially 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 decrease the rate of miscarriage and increase the chances of pregnancy.
Uterine hypoplasia: small uterus
Uterine hypoplasia or infantile womb refers to an underdeveloped uterus, most often caused by a fetal malformation or an episode of malnutrition in the infant. An adult woman's womb is usually 7-8 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 first one corresponds to an organ whose growth is stopped directly after birth. It therefore measures no more than 4 cm. Women with embryonic hypoplasia suffer from amenorrhea and infertility.
The second is a womb that stops growing during infancy. Its maximum length will be 5 cm. Pregnancy is still 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 the vagina
Uterovaginal aplasia is a rare birth defect that results in theabsence of a 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 often suffer from a lack of menstruation and have difficulty with sexual intercourse.
What about the contractile uterus?
The term "contractile"does not refer to a malformation of the uterus. Rather, it refers to a dysfunction that occurs during pregnancy. The uterus of a pregnant woman 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 quickly. Indeed, a contractile uterus can lead to an opening of the uterine cervix and cause a miscarriage or a premature delivery.
How do you get diagnosed with a certain type of uterus?
Many women do not know the shape of their uterus. Some types, such asanteverted or retroverted, are so common that they usually go unnoticed during a gynecological examination. This is especially true if the patient has no significant symptoms. A midwife or gynecologist can, however, identify a certain shape of uterus by a simple vaginal touch or by examining the cervix after placing a speculum.
A uterine malformation does not always mean amenorrhea or fertility problems. Some women with a bicornuate uterus, for example, have perfectly normal pregnancies and only discover this morphological feature during their pregnancy.
However, if you suffer from a lack of menstruation, severe pain during your period or if you have difficulty getting pregnant, make an appointment with a health care professional for a check-up.
To diagnose a uterine anomaly, a medical imaging test is necessary. An ultrasound, a hysteroscopy (exploration of the uterine cavity through a hysteroscope) or a hysterography (x-ray of the uterus) can detect a possible malformation and allow for quick treatment.
FAQ on the different shapes of the uterus
What is the normal shape of the uterus?
Women most often have an anteverted (forward tilted) uterus. However, some women may have a retroverted uterus (tilted backwards). Both forms are perfectly normal.
Is it serious to have a small uterus?
It depends on the degree of uterine hypoplasia. If the uterus is no larger than 4 cm, it leads to a lack of menstruation and infertility. On the other hand, if it measures 5 cm, a pregnancy is possible. However, it will have to be carefully monitored, as it is considered to be high risk.
In which cases should I consult a doctor about my uterus?
If you suffer from amenorrhea, if your periods are very painful or if you are unable to get pregnant, consult your gynecologist or midwife without delay in order to have your uterus examined.
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