The length of the cervical canal: structure, indicators of the norm, pathology
The length of the cervical canal: structure, indicators of the norm, pathology

Video: The length of the cervical canal: structure, indicators of the norm, pathology

Video: The length of the cervical canal: structure, indicators of the norm, pathology
Video: 38 Weeks Pregnant | Pregnancy Week by Week and Signs of Labor - YouTube 2023, September

There is no doubt about the uniqueness of the female body. Mother nature provides for everything in the smallest detail. The device of a woman's body allows the formation of a fetus, which begins its journey with a set of cells, subsequently turning into an embryo, and by the beginning of the third trimester it already resembles a person. After fertilization of the egg, the body enters a new phase, the purpose of which is the development of a new life. The length of the cervical canal plays an important role in this process.

The length of the cervical canal - the norm
The length of the cervical canal - the norm

It is not for nothing that doctors pay close attention to this parameter at the appointment at the antenatal clinic. Fixing the length of the cervix allows you to timely detect the presence of a particular pathology, as well as take all necessary measures to avoid serious complications. But what length is considered to be the norm, and in what case is this a sign of deviation? Actually, this is the subject of this article.

General information

To begin with, let's reveal the essence of the concept of the cervical canal - what is it all about? In fact, this is a segment that connects the vagina to the cavity of the reproductive organ. In the language of doctors, it is called a pharynx. It is through it that the seminal fluid passes for fertilization of the egg, as well as excretion during menstruation.

The size of the channel is directly dependent on whether the girl gave birth or not. The standard throat diameter is no more than 3 mm. Moreover, if the girl has not yet become a mother, then at the gynecological examination the doctor will see a dot, and for women who have already given birth - a gap. As for the length of the cervical canal, here are the following dimensions:

  • for nulliparous girls - 40 mm;
  • mothers up to 80 mm.

During the second pregnancy, it can be considered normal if, during the examination, the pharynx misses a finger. At the same time, the length of the neck should not be less than 20 mm. Otherwise, it clearly indicates isthmic-cervical insufficiency (ICI).

The role of the cervical canal during pregnancy

The role of the cervical canal during pregnancy
The role of the cervical canal during pregnancy

The main functions of the pharynx are as follows:

  • This lumen connects the vagina and the uterine cavity, menstrual flow passes through it, which indicates the absence of pregnancy. But if the girl did not have her first menstrual bleeding (menarche), then the problem lies in the obstruction of the cervical canal.
  • Formation of a mucous plug along the entire length of the cervical canal during pregnancy. This substance helpspromotion of male germ cells into the cavity of the reproductive organ. Mucus provides protection against infection because it has bactericidal properties. During pregnancy, it hardens, and a cork forms, finally closing the passage into the uterus. This forms a physical barrier that prevents the penetration of any pathogenic microorganisms into the organ cavity.
  • At the stage of enlargement of the genital organ, the canal becomes smaller (this is not a pathology) and denser. This measure avoids premature rupture of amniotic fluid.
  • During childbirth, the canal is able to stretch in order to miss the baby.

As for the cork, it lasts for all 9 months, while a woman wears a child under her heart. And together with the opening of the pharynx, she leaves on her own. But how is the length of the cervical canal determined by weeks of pregnancy and in the normal physiological state?


This term should be understood as the method of ultrasound examination of the cervical canal. It allows doctors to find out not only its length, but also other parameters. In addition, ultrasound helps to determine the size of the internal and external os.

The examination itself is carried out using a transvaginal sensor, with the help of which all the parameters of the canal are determined. This procedure does not cause pain in women and is easily tolerated by them.

The technique is based on the principle of reflection of outgoing ultrasonic waves from biological structures of various types. Typically, ultrasoundcan be carried out not only in a hospital, but also during a visit to the clinic.

Intravaginal ultrasound
Intravaginal ultrasound

In addition, the length of the cervix along the cervical canal can be determined during a planned visit by pregnant women to a doctor for a gynecological examination. The specialist reveals its size by touch. Moreover, in this way, not only the length is determined, but also the density, localization, expansion.

Normal indicators

Normally, the cervical canal is in a closed state, which allows you to keep the fetus in the cavity of the reproductive organ throughout the entire period of pregnancy. Usually, the condition of the pharynx is recorded during the standard diagnostic procedure. But if there is any suspicion, the doctor prescribes an additional study to the patient, which will confirm the diagnosis or refute it.

Also, women will have to take all the necessary tests. This will allow doctors to make an objective clinical picture of the current situation both in relation to the woman herself and her child.

The length of the cervical canal from the 20th week of pregnancy begins to change and, starting from this period, doctors already fix this parameter every seven days. This is done in order to timely detect deviations from the norm, if any.

Changing the length of the channel by week of pregnancy

With the onset of the first trimester of pregnancy, the length of the channel is 40 mm, which is within the normal range. In the second period of gestation, the canal begins to shorten, and the pharynx itself expands. At this time, a length of 35 is considered the Before childbirth, at 36-37 weeks, the length of the canal becomes even smaller - up to 30 mm, which is also not a pathology. A week before delivery, this value becomes even slightly smaller, while the pharynx is expanded to 100 mm. A more accurate idea of the change in the length of the channel will provide the table below.

Table of changes in the length of the cervical canal by week of pregnancy is normal.

Pregnancy term (by week) Channel length (in mm)
From 10 to 14 34-36
From 15 to 19 38-39
20 to 25 40
25 to 29 41
30 to 32 30-33
From 32 to 36 33-36
From 36 to 40 29-30

From the table above, it is clearly seen that at a period of 12 to 15 weeks of pregnancy, the length of the canal is almost the same as its length in girls outside this physiological state. Of course, subject to the woman's physical he alth.

The length of the cervical canal during pregnancy
The length of the cervical canal during pregnancy

The length of the cervical canal begins to increase from the 16th week of pregnancy. And at 19 weeks it is already 39 mm, and by the 29th it reaches a maximum of 41 mm. In other words, the cervical canal begins to gradually increase from the second trimester of pregnancy. But then the sizes decrease - and all this is the norm.

Channel lengthening

For 9 months of bearing a child, the length of the cervical canal during pregnancy is normalfirst increases and then decreases, and this is not a pathology. But what if the channel size does not correspond to the average value in a certain period? Is this the norm or can this phenomenon already be regarded as a pathology? To begin with, consider the reasons for the lengthening of the cervical canal:

  • anatomical structure of innate character;
  • frequent inflammation of the female reproductive system;
  • injured;
  • surgery.

Due to the elongated size of the canal, a violation of the process of fertilization and fetal development, including subsequent delivery, may occur. In addition, the uterine os undergoes undesirable changes, and the placenta itself may not properly attach to the wall of the uterus. At the same time, cases of post-term pregnancy are not uncommon due to the fact that the reproductive system is not yet ready for childbirth.

In addition, when the length of the cervical canal deviates from the norm, it has a solid structure. Consequently, it does not stretch well and therefore does not ripen by the required date. In addition, the duration of contractions increases, which leads to a weakening of the female body and the complication of delivery. As a rule, in such situations, they resort to the stimulation of labor.

Too long channel should be attributed to pathology. This condition does not lead to anything good, and therefore requires the intervention of specialists. For this reason, research is being carried out in the antenatal clinic.

Provoking factors

The length of the cervical canal varies throughoutall 9 months of pregnancy. At the same time, this process is normally influenced by hormones and a number of other reasons.

Position of the cervix during early pregnancy
Position of the cervix during early pregnancy

However, provoking factors that contribute to the deviation of the length of the cervical canal at 12 weeks from the norm (or at any other time) cannot be ruled out. Some of them do not bode well:

  • Hormonal imbalance. Biologically active substances provide control over pregnancy. They also provide the preparation of the reproductive system of the female body for labor. For this reason, the occurrence of an imbalance inevitably causes a deviation in the length of the cervical canal from the normal limits.
  • Injury to the cervix during surgery. In particular, we are talking about abortions or previous births. In this case, the cervix may become shorter or longer.
  • Diseases of the reproductive system of an infectious nature.
  • Features of the anatomical structure.
  • Stress. No wonder experts recommend that pregnant women avoid strong excitement. It is important for any future mother to ensure peace, since a stable state helps to maintain hormonal levels within normal limits. Stressful situations (especially strong ones) can provoke various pathologies in the development of the fetus.

For this reason, it is necessary to constantly monitor the length of the cervical canal during pregnancy. This will allow timely action to be taken.

Channel expansion

Whenof patients, an expansion of the cervical canal is detected, they are sent to the hospital. The need for this decision is largely due to the fact that this sign indicates the ICI. That is, the cervix itself has already been opened ahead of schedule. The fetus, increasing in size, puts even more pressure on it. And if we are talking about multiple pregnancy, then this phenomenon is almost always observed due to the specifics of this situation.

Isthmic-cervical insufficiency
Isthmic-cervical insufficiency

To eliminate the pathology, drug therapy or a surgical method is used. With the help of medications, it is possible to bring the hormonal background back to normal, as well as eliminate the hypertonicity of the reproductive organ.

Inflammatory pathology

The impact of pathogenic microorganisms on the cervical canal contributes to the development of the inflammatory process. This condition is called endocervicitis. As a rule, inflammation is due to the presence of a wound (along the entire length of the cervical canal or in a certain part of it). Microorganisms such as chlamydia and staphylococcus aureus can cause a similar reaction even if the channel is not injured.

The danger of endocervicitis is as follows:

  • uterine hypertonicity;
  • insufficient supply of oxygen to the fetus;
  • loosening of the fetal membrane;
  • premature onset of labor.

During the gynecological examination of the patient, on the basis of the above signs, the specialist diagnoses endocervicitis. To determine the course of treatment, a smear is taken, which is examined in the laboratory.conditions. First you need to find out the type of pathogen and only then determine the drug to combat it.

Since not all medicines are allowed for use by pregnant women, preference is given to local remedies: suppositories, capsules. The appointment of a particular drug for external use should only be handled by a highly qualified doctor. In addition, one should take into account not only the type of pathogen, but also the duration of pregnancy.

A frightening diagnosis

In some cases, in the course of determining whether the length of the cervical canal is normal for a week of pregnancy or not, doctors can detect the presence of a polyp. Many girls are afraid of such a diagnosis.

Polyp of the cervical canal
Polyp of the cervical canal

However, in this case, there are two ways of development:

  • True polyp. Often, its presence causes problems with conception. For this reason, when planning a pregnancy, it should certainly be removed. After that, the woman needs to undergo drug therapy to avoid relapses.
  • Pseudopolyp develops only in expectant mothers. At the same time, the growth itself does not have any effect on the he alth and well-being of a woman and her child. And after childbirth, it dissolves on its own. The reason for the appearance of this neoplasm is a change in the hormonal background in the female body. Since it is eliminated by itself, there is no need to resort to a surgical operation, it is enough to treat it with any antiseptic agent.

At the same time, a true polyp can also be found in pregnant women. Only in this case, he should not be disturbed before the birth of the child, only vigilant monitoring of his condition during routine examinations of the length of the cervical canal should be carried out. This will allow you to prevent any complications in a timely manner. Only in the most severe cases, despite the special situation of a woman, is surgical intervention prescribed when there is a threat to the life of the mother.


Inside each of us, all systems are united into a single whole, which is called in one word - the body. Moreover, each of them consists of organs, and the efficiency of all processes depends on their he alth. And pregnancy in this case is no exception.

What conclusion can be drawn from all of the above? One thing can be said with certainty - determining the length of the cervical canal by weeks of pregnancy is a fundamental way to control this process. It is important to ensure the observation of the dynamics of changes in its length in order to timely identify the pathology and start the appropriate course of treatment, depending on the provoking factor.

Gynecological examination
Gynecological examination

This will keep the pregnancy until the end of the term, and the baby will be born completely he althy and happy to the delight of the parents. It's definitely not worth joking with your he alth, and even more so with your own child.