Uterus – structure, function, diseases

Today we know that the uterus is a complex organ with many different functions. And it is precisely this complexity that can promote the occurrence of various complaints and illnesses such as pain, difficulties getting pregnant or bleeding disorders. If you notice health problems around the uterus over a longer period of time, you should not hesitate to seek medical advice. As a rule, the symptoms can be treated well.

What is the uterus?

The uterus is part of the female reproductive organs. The muscular hollow organ, which is about the size of a fist, plays a central role in the reproductive system, as a child grows inside it after fertilization.

The uterus also performs important functions outside of pregnancy. During the menstrual cycle, it regularly builds up its mucous membrane to enable the potential implantation of an embryo. It sheds this mucous membrane again if pregnancy does not occur. These processes are subject to complex hormonal control and are a central component of a healthy female cycle.

In addition, the uterus produces certain messenger substances (such as prostaglandins) that support its ability to contract and play a role in menstruation and childbirth. It also contributes to the stability of the pelvic organs via its retaining ligaments.

Position of the uterus: Where is the uterus located?

The uterus is located in the small pelvis, i.e. in the lower part of the abdomen. It is located behind the bladder and in front of the rectum and is elastically suspended with the help of ligaments. As a result, their position can change slightly depending on the filling of the surrounding organs or in the course of the cycle.

Uterine anatomy: How is the uterus structured?

The uterus is a pear-shaped, muscular hollow organ that measures around seven to nine centimeters when not pregnant. The uterus weighs about 50 to 80 grams. Their size and shape can change over the course of a lifetime – for example after childbirth, during the menopause or due to hormonal influences.

The uterus is divided anatomically into three central areas:

• Fundus uteri: The upper, curved section of the uterus above the fallopian tubes.
• Corpus uteri: The largest part of the uterus in which the uterine lining builds up and a pregnancy can develop after fertilization.
• Cervix uteri (neck of the womb): The lower, narrow part that opens into the vagina. The cervix forms a canal that produces mucus and serves as a barrier against germs. Its opening, through which a baby is born in the event of pregnancy, is known as the cervix.

Structure of the uterus: The uterine wall and its functions

The uterine wall is the “mantle” of the uterus. It encloses the uterine cavity and enables both the menstrual cycle and the strong expansions and contractions during pregnancy and birth.

Structure of the uterine wall and endometrium

The uterine wall consists of three layers, each of which has different functions:

• Endometrium (lining of the uterus): The inner layer of the uterine mucosa builds up and breaks down rhythmically during the menstrual cycle. It enables the implantation of a fertilized egg or is rejected during menstruation.
• Myometrium: The strong uterine muscle layer, which consists of smooth muscle. It causes contractions – both during menstruation and during labor during childbirth.
• Serosa: The outer, thin layer of connective tissue that envelops the uterus on the outside and separates it from the abdominal cavity.

Suspension and supply of the uterus

The uterus is held elastically in the pelvis by various ligaments. In this way, it remains stable and can adapt to changes in the abdominal cavity at the same time.

A dense network of blood vessels and nerves continuously supplies them with oxygen and nutrients as well as the signals that control their contractions. The uterine artery and the ovarian artery are among the most important vessels in the uterus.

Task and function of the uterus

The uterus forms the center of the female reproductive system. It plays a key role in the menstrual cycle, pregnancy and childbirth.

The function of the uterus in the female cycle

Every month, the uterus of women of childbearing age prepares for a possible pregnancy. The mucous membrane builds up under the influence of the hormones estrogen and progesterone. If no fertilized egg is implanted, this layer is shed again – menstruation begins. However, if fertilization occurs, the egg cell implants in the uterine lining.

The function of the uterus for pregnancy and birth

The uterus offers the growing embryo protection, support and suitable care. During pregnancy, it enlarges many times over and adapts to the growth of the child. The myometrium stretches increasingly and prepares for birth. During birth, the muscles of the uterus contract rhythmically. These contractions – known as contractions – enable the baby to be born through the birth canal.

Uterine functions: Protection against infection and stability in the pelvic floor

The uterus forms an important barrier against infections: With its mucus and narrow canal, the cervix makes it difficult for germs to penetrate. At the same time, the uterus supports the surrounding organs such as the bladder and bowel and contributes significantly to the stability and balance of the entire pelvic floor. Its suspension straps also help to maintain anatomical order in the pelvis and support its function.

Like any organ, the uterus can also become diseased. Many diseases are benign and easily treatable, but others can have serious consequences or significantly impair quality of life. The most common diseases include fibroids, endometriosis, polyps, adenomyosis, inflammatory changes and menstrual cycle disorders. Here you will find an overview of the most important diseases of the uterus:

Abnormal uterine bleeding (AUB)

Abnormal uterine bleeding (AUB) is when menstrual bleeding is heavier, longer or more irregular than usual. This can also include bleeding between periods or after sexual intercourse. Possible causes are hormonal changes, polyps, fibroids, adenomyosis, endometriosis or blood clotting disorders. In some cases, no clear cause can be found. The changes can severely affect everyday life, but are usually easy to treat. Depending on the trigger, drug therapies, hormonal methods or surgical procedures may be considered.

• Read here how we treat menstrual cramps at the USZ.

Myomas

Myomas are benign growths of the uterine muscles. Individual muscle fibers, which are normally arranged in a regular pattern, grow together to form one or more nodes. Myomas often occur in women between the ages of 30 and 50, i.e. at a time when the hormone balance is particularly active. Myomas often change positively during the menopause. They become smaller and hardly cause any symptoms.

Although fibroids are not malignant, they can cause significant discomfort in around half of the women affected, for example heavy or prolonged monthly bleeding, lower abdominal pain or a feeling of pressure in the pelvis.

The treatment depends on the size, location, symptoms and desire to have children. Depending on the situation, drug therapies, minimally invasive procedures such as myoma embolization or surgical procedures in which individual fibroids or, in certain cases, the entire uterus are removed may be considered. If there are no or only mild symptoms, regular medical check-ups are often sufficient.

• More on the clinical picture of fibroids
• More about treatment for fibroids

Endometriosis

In endometriosis, cells of the uterine lining grow outside the uterine cavity. These so-called endometriosis lesions are usually benign. While some women hardly notice them, others experience severe pain or bleeding – especially during menstruation, but sometimes also independently of the menstrual cycle. Endometriosis can also affect fertility and be a cause of an unfulfilled desire to have children. There is currently no cure, but various treatment options are available to alleviate the symptoms and improve quality of life.

• More on the clinical picture of endometriosis
• More on treatment for endometriosis

Inflammation of the uterus (endometritis)

Uterine inflammation is an inflammation of the lining of the uterus. It is usually caused by ascending bacteria, for example after childbirth, a miscarriage, an operation, the insertion of an IUD or infections. Typical symptoms are lower abdominal pain, fever, unusual or foul-smelling discharge and a general feeling of illness. Uterine inflammation is usually treated with antibiotics and is usually uncomplicated if treated in good time.

Adenomyosis

In adenomyosis, tissue from the lining of the uterus grows into the muscle layer of the uterus. This can cause the uterus to enlarge and severe menstrual pain or bleeding may occur. While some women hardly feel a thing, others suffer from chronic pain or have difficulty getting pregnant. Although adenomyosis is benign, it can significantly impair the quality of life. Various forms of treatment – medicinal or surgical – can alleviate the symptoms. Which therapy is suitable depends on the severity of the symptoms, the age and the desire to have children.

Polyps in the uterus

Uterine polyps are benign growths of the uterine lining. They occur when individual areas of the mucous membrane multiply excessively and form small protrusions into the uterine cavity. They often cause no symptoms. However, some women notice irregular or heavier bleeding, intermenstrual bleeding or spotting. Polyps can impair fertility if they interfere with the implantation of a fertilized egg.

Removal of polyps in the uterus: Uterine polyps are usually removed by means of a minor surgical procedure (polypectomy), which quickly relieves the symptoms.

Polyzystisches Ovarsyndrom (PCO-Syndrom)

Polycystic ovary syndrome is a disease with very different manifestations and is the most common hormonal disorder in young women. Some sufferers experience irregular (oligomenorrhea) or absent periods (amenorrhea), while shortened cycles are less common. Others suffer mainly from skin problems or increased body hair, often caused by increased male hormones in the blood (hyperandrogenemia). Often, but not in all cases, the ovaries show an increased number of small follicles.

• More on the clinical picture of PCO syndrome

Background: What is a curettage of the uterus?

During a curettage, a short and usually outpatient procedure, the lining of the uterus is carefully removed via the cervix. It is used to clarify unusual bleeding, remove polyps or mucosal residues or obtain tissue samples. The treatment only takes a few minutes, is usually performed under light anesthesia and usually leads to a quick recovery with only slight, temporary discomfort.

• More about colposcopy, biopsy and endocervical curettage

Uterine prolapse (after birth)

In the case of uterine prolapse, the uterus sinks downwards towards the vagina. Ursache ist meist eine Schwächung der Beckenbodenmuskulatur und der Haltebänder, die häufig nach einer Schwangerschaft und Geburt, in den Wechseljahren oder bei Bindegewebsschwäche auftritt. Lighter forms often cause no symptoms. If the prolapse is more severe, a feeling of pressure or a foreign body in the abdomen, back pain or problems urinating may occur. Bladder or bowel emptying disorders are also possible. The treatment depends on the extent of the prolapse and the symptoms. It ranges from pelvic floor exercises and the insertion of a pessary to surgical procedures.

• More on the treatment of uterine and/or bladder prolapse

Cervicitis

In cervicitis, the mucous membrane of the cervix is inflamed. This can be caused by bacteria or viruses such as chlamydia, gonococci or HPV. Some women have no complaints. Others notice increased or unusual discharge, intermenstrual bleeding or pain during sexual intercourse. Untreated cervicitis can promote ascending infections. Treatment depends on the pathogen and includes antibiotics, antiviral therapies or local measures, depending on the cause. Early diagnosis helps to alleviate symptoms quickly and avoid complications.

Shortened cervix

A shortened cervix means that it is shorter than usual. This can be particularly important during pregnancy, as a cervix that is too short can increase the risk of premature birth .

Endometrial cancer (cancer of the lining of the uterus)

Endometrial carcinoma is a malignant tumor of the uterine lining. It usually occurs after the menopause and is often characterized by unusual or renewed bleeding, especially after menstruation has already stopped. If detected early, the disease can be treated well in many cases. The most important treatment is usually surgical removal of the uterus and ovaries. Depending on the stage, this operation is supplemented by other treatments such as radiotherapy or hormone therapy. Risk factors include obesity, long-term estrogen effects and certain pre-existing conditions.

Cervical carcinoma (cancer of the cervix)

Cervical cancer develops from cells in the cervix and usually takes many years to develop. The most common cause is a persistent infection with certain types of the human papillomavirus (HPV). Early stages often cause no symptoms. Later, intermenstrual bleeding, bleeding after sexual intercourse or unusual discharge may occur. Regular screening examinations and the HPV test allow precancerous stages to be detected and treated at an early stage. The therapy depends on the stage and ranges from surgical procedures to radiotherapy or chemotherapy. HPV vaccination offers effective protection against the most common cancer-causing virus types.

You can find out which warning signs you should take seriously, how cervical cancer is diagnosed and which therapy and treatment options are available today for cervical cancer in our detailed article Cervical cancer.

Not all bleeding or pulling in the abdomen is a cause for concern – but you should always have certain symptoms checked out by a doctor. These include unusual or very heavy bleeding, bleeding after the menopause, persistent lower abdominal pain, a feeling of pressure or a foreign body in the vagina, an unfulfilled desire to have children, fever or changes in discharge. An early examination is important because many diseases – especially tumors – are easier to treat if they are detected early.

In the event of abnormal symptoms or unclear findings, we at the USZ can reliably clarify the cause using various diagnostic procedures.

The examination methods at a glance:

• Gynecological examination and smear test
• Uterine ultrasound (sonography) – usually the first step
• Uteroscopy (hysteroscopy) – direct view into the uterus
• Tissue sample (biopsy) – to clarify suspicious changes
• MRI or CT – for tumors or complex findings

Prevention and precaution: How does the uterus stay healthy?

Many uterine diseases can be positively influenced by regular preventive care and a health-conscious lifestyle. These include gynecological check-ups such as smear tests and ultrasounds, the HPV vaccination to protect against cervical cancer and a lifestyle that includes diet, exercise and stress management. You should also keep an eye on hormonal changes – for example during the menopause. These measures help to keep the uterus healthy in the long term and to detect changes at an early stage:

• Go for regular check-ups: Gynaecological check-ups help to detect changes at an early stage.
• Pay attention to diet and exercise: A varied diet and regular activity are good for the whole body – including the uterus.
• Reduce stress: Time out, relaxation or small breaks in everyday life support a balanced cycle.
• Do not smoke: Avoiding nicotine reduces the risk of various diseases.
• Gentle intimate hygiene: Mild cleansing, not over-care – this keeps the natural vaginal flora in balance.
• Strengthen the pelvic floor: Exercises for the pelvic floor can improve well-being and prevent later complaints.

Life after a uterine disease or hysterectomy

A disease of the uterus or the prospect of having it removed can be very emotionally stressful. For many women, the uterus has a special meaning, for example in connection with femininity, fertility and their own body image. Such thoughts and feelings are completely understandable.

Menopause without a uterus

Patients should not lose their courage. Even after a hysterectomy during the menopause, the hormonal balance is largely maintained as long as the ovaries remain intact. This also applies to the removal of the uterus before the menopause. Your well-being, your sexuality and your self-esteem are not tied to a single organ. At our clinic for reproductive endocrinology, we provide you with holistic support on your journey. In addition to competent medical treatment, we also offer psychological support and physiotherapy to ensure that your body and soul receive the best possible care during this time.