Until the 16th century, it was believed that the pelvic bones diverge during childbirth, and the fetus is born with its legs resting on the bottom of the uterus. In 1543, the anatomist Vesalius proved that the bones of the pelvis are connected immovably, and doctors turned their attention to the problem of a narrow pelvis.
Despite the fact that in Lately gross deformities of the pelvis and high degrees its narrowing is rare; the problem of a narrow pelvis has not lost its relevance today - due to the acceleration and increase in body weight of newborns.
Causes
The causes of narrowing or deformation of the pelvis can be:
- congenital anomalies pelvis,
- malnutrition in childhood,
- diseases suffered in childhood: rickets, polio, etc.
- diseases or damage to the bones and joints of the pelvis: fractures, tumors, tuberculosis.
- spinal deformities (kyphosis, scoliosis, coccyx deformity).
- One of the factors in the formation of a transversely narrowed pelvis is acceleration, which leads to rapid growth of the body in length while the growth of transverse dimensions lags.
Kinds
Anatomically narrow A pelvis is considered to be one in which at least one of the main dimensions (see below) is 1.5-2 cm or more smaller than normal.
However highest value have not the dimensions of the pelvis, but the ratio of these dimensions to the dimensions of the fetal head. If the fetal head is small, then even with some narrowing of the pelvis there may not be a discrepancy between it and the head of the born child, and childbirth takes place naturally without any complications. In such cases, an anatomically narrowed pelvis turns out to be functionally sufficient.
Complications during childbirth can also occur when normal sizes pelvis - in cases where the fetal head is larger than the pelvic ring. In such cases, the advancement of the head along the birth canal is suspended: the pelvis practically turns out to be narrow and functionally insufficient. Therefore, there is such a thing as clinically (or functionally) narrow pelvis . A clinically narrow pelvis is an indication for cesarean section during childbirth.
A true anatomically narrow pelvis occurs in 5-7% of women. The diagnosis of a clinically narrow pelvis is established only during childbirth based on a combination of signs that make it possible to identify the disproportion between the pelvis and the head. This type of pathology occurs in 1-2% of all births.
How is the pelvis measured?
In obstetrics, examination of the pelvis is very important, since its structure and dimensions have crucial for the course and outcome of childbirth. The presence of a normal pelvis is one of the main conditions for the correct course of labor.
Deviations in the structure of the pelvis, especially a decrease in its size, complicate the course of natural birth, and sometimes present insurmountable obstacles for them. Therefore, when registering a pregnant woman with an antenatal clinic and upon admission to the maternity hospital, in addition to other examinations, the external dimensions of the pelvis must be measured. Knowing the shape and size of the pelvis, you can predict the course of labor, possible complications, and make a decision about the admissibility spontaneous labor.
A pelvic examination includes examining, palpating the bones and determining the size of the pelvis.
In a standing position, the so-called lumbosacral rhombus, or Michaelis rhombus, is examined (Fig. 1). Normally, the vertical size of the rhombus is on average 11 cm, the transverse size is 10 cm. If the structure of the small pelvis is disturbed, the lumbosacral rhombus is not clearly expressed, its shape and size are changed.
After palpating the pelvic bones, it is measured using a pelvis meter (see Fig. 2a and b).
Main dimensions of the pelvis:
- Interspinous size. The distance between the superior anterior iliac spines (in Fig. 2a) is normally 25-26 cm.
- The distance between the most distant points of the iliac crests (in Fig. 2a) is 28-29 cm, between the greater trochanters femur(in Fig. 2a) - 30-31 cm.
- External conjugate - the distance between the suprasacral fossa (upper corner of the Michaelis rhombus) and top edge pubic symphysis (Fig. 2b) - 20-21 cm.
The first two sizes are measured with the woman lying on her back with her legs extended and brought together; the third size is measured with the legs shifted and slightly bent. The external conjugate is measured with the woman lying on her side with the underlying leg bent at the hip and knee joints and the overlying leg extended.
Some pelvic dimensions are determined during a vaginal examination.
When determining the size of the pelvis, it is necessary to take into account the thickness of its bones; it is judged by the value of the so-called Solovyov index - circumference wrist joint. The average index value is 14 cm. If the Solovyov index is more than 14 cm, it can be assumed that the pelvic bones are massive and the size of the small pelvis is smaller than expected.
If it is necessary to obtain additional data on the size of the pelvis, its correspondence to the size of the fetal head, deformation of the bones and their joints, X-ray examination pelvis But it is performed only according to strict indications. The size of the pelvis and its correspondence to the size of the head can also be judged from the results of an ultrasound examination.
The influence of a narrow pelvis on the course of pregnancy and childbirth
The adverse effect of a narrowed pelvis on the course of pregnancy is felt only in its last months. The fetal head does not descend into the pelvis, the growing uterus rises and makes breathing much more difficult. Therefore, at the end of pregnancy, shortness of breath appears early, it is more pronounced than during pregnancy with a normal pelvis.
In addition, a narrow pelvis often leads to incorrect position fruit - transverse or oblique. 25% of women in labor with a transverse or oblique position of the fetus usually have a pronounced narrowing of the pelvis to one degree or another. Breech presentation fetus in women in labor with a narrowed pelvis occurs three times more often than in women in labor with a normal pelvis.
Management of pregnancy and childbirth with a narrow pelvis
Pregnant women with a narrow pelvis belong to the group high risk regarding the development of complications, and in antenatal clinic must be specially registered. Necessary timely detection fetal position abnormalities and other complications. It is important to accurately determine the due date in order to prevent post-term pregnancy, which is especially unfavorable with a narrow pelvis. 1-2 weeks before birth, pregnant women with a narrow pelvis are recommended to be hospitalized in the pathology department to clarify the diagnosis and choose a rational method of delivery.
The course of labor with a narrow pelvis depends on the degree of narrowing of the pelvis. With slight narrowing, medium and small fetal sizes are possible vaginal birth. During childbirth, the doctor carefully monitors the function the most important organs, character ancestral forces, the condition of the fetus and the degree of correspondence between the fetal head and the pelvis of the woman in labor and, if necessary, promptly resolves the issue of caesarean section.
Absolute indications for caesarean section are:
- anatomically narrow pelvis of III-IV degree of narrowing;
- the presence of bone tumors in the pelvis that impede the passage of the fetus;
- severe deformations of the pelvis as a result of injury or illness;
- ruptures of the symphysis pubis or other pelvic injuries that occurred during previous births.
In addition, the indication for caesarean section is a combination of a narrow pelvis with:
- large fruit size,
- post-term pregnancy,
- chronic fetal hypoxia,
- breech presentation,
- abnormal development of the genital organs,
- scar on the uterus after cesarean section and other operations,
- indication of a history of infertility,
- the age of the primigravida is over 30 years, etc.
Caesarean section is performed at the end of pregnancy before or with the onset of labor.
The examination plan for a pregnant woman must include measuring the pelvis. This procedure is often performed at the first appointment for every woman who consults an obstetrician-gynecologist about the desired pregnancy. Bone pelvis and soft fabrics lining it are the birth canal through which the baby is born. It is extremely important for doctors and women to know whether the birth canal is too small for the baby. This circumstance determines the possibility of childbirth through the natural birth canal. The results of the pelvic examination are included in medical documents. So that you can understand what is written on your exchange card, we will talk in detail about what the doctor does when measuring a pregnant woman’s pelvis.
Measuring the pelvis during pregnancy
The structure and size of the pelvis are crucial for the course and outcome of childbirth. Deviations in the structure of the pelvis, especially a decrease in its size, complicate the course of labor or present insurmountable obstacles to it.
The pelvis is examined by inspection, palpation and measurement. During the examination, attention is paid to the entire pelvic area, but special importance is attached to the sacral rhombus (Michaelis rhombus, Fig. 1), the shape of which, together with other data, allows us to judge the structure of the pelvis (Fig. 2).
Rice. 1. Sacral rhombus, or Michaelis rhombus
Rice. 2. Pelvic bones
Most important of all methods of pelvic examination has its measurement. Knowing the size of the pelvis, one can judge the course of labor, the possible complications with them, about the admissibility of spontaneous childbirth with a given shape and size of the pelvis. Most of the internal dimensions of the pelvis are not available for measurement, so the external dimensions of the pelvis are usually measured and the size and shape of the small pelvis can be approximately judged from them. The pelvis is measured special tool- pelvis gauge. The pelvis meter has the shape of a compass equipped with a scale on which centimeter and half-centimeter divisions are marked. There are buttons at the ends of the branches of the tazomer; they are applied to places the distance between which is to be measured. The following pelvic sizes are usually measured: (Indicated in parentheses Latin names and abbreviations, since the dimensions are indicated that way in the exchange card.)
Distance spinarum (DistantiasplnarumD.sp.) - the distance between the anterior-superior spines iliac bones. This size is usually 25-26 cm (Fig. 3).
Rice. 3. Measuring spinarum distance
Distance cristarum (Distantiacristarum D. Cr.) - the distance between the most distant points of the iliac crests. It averages 28-29 cm (Fig. 4).
Rice. 4. Crystarum distance measurement
Treanteric distance (Distantiatrochanterica D. Tr.) - the distance between the greater trochanters of the femurs. This size is 31 -32 cm (Fig. 5).
Rice. 5. Measuring the distance of the triangular
External conjugate (Conjugata externaС. Ext.) - external conjugate, i.e. straight pelvic size. To do this, the woman is laid on her side, the underlying leg is bent in
hip and knee joints, the overlying one is pulled out. The external conjugate is normally 20-21 cm (Fig. 6).
Rice. 6. Measuring the outer conjugate
The external conjugate is important: by its size one can judge the size of the true conjugate - the distance between the sacral promontory - the most protruding point inside the sacrum and the most protruding point on inner surface pubic symphysis (the junction of the pubic bones). This smallest size inside the pelvis through which the fetal head passes during childbirth. If the true conjugate is less than 10.5 cm, then vaginal delivery may be difficult or simply impossible; in this case it is often performed C-section. To determine the true conjugate, subtract 9 cm from the length of the outer conjugate. For example, if the outer conjugate is 20 cm, then the true conjugate is 11 cm; if the outer conjugate has a length of 18 cm, then the true one is 9 cm, etc. The difference between the external and true conjugates depends on the thickness of the sacrum, symphysis and soft tissues. The thickness of bones and soft tissues varies in women, so the difference between the size of the external and true conjugate does not always exactly correspond to 9 cm. The true conjugate can be more accurately determined by the diagonal conjugate.
The diagonal conjugate (conju-gatadiagonalis) is the distance from the lower edge of the symphysis to the most prominent point of the sacral promontory. The diagonal conjugate is determined when vaginal examination women (Fig. 7). The diagonal conjugate with a normal pelvis is on average 12.5-13 cm. To determine the true conjugate, subtract 1.5-2 cm from the size of the diagonal conjugate.
Rice. 7. Diagonal conjugate measurement
The doctor is not always able to measure the diagonal conjugate, because with normal pelvic sizes during a vaginal examination, the promontory of the sacrum is not reached by the examiner’s finger or is difficult to palpate. If during a vaginal examination the doctor does not reach the promontory, the volume of this pelvis can be considered normal. The dimensions of the pelvis and the external conjugate are measured in all pregnant women and women in labor without exception.
If during examination of a woman there is a suspicion of narrowing of the pelvic outlet, then the size of this cavity is determined. These measurements are not mandatory, and are measured in a position in which the woman lies on her back, legs bent at the hips and knee joints, spread to the side and pulled up to the stomach.
Determining the shape of the pubic angle is important. With normal pelvic sizes it is 90-100. The shape of the pubic angle is determined next step. The woman lies on her back, legs bent and pulled up to her stomach. Palm side thumbs applied close to the lower edge of the symphysis. The location of the fingers allows us to judge the angle of the pubic arch.
Additional Research
If it is necessary to obtain additional data on the size of the pelvis, its correspondence to the size of the fetal head, deformations of the bones and their joints, an X-ray examination of the pelvis is performed - X-ray pelviometry. Such a study is possible at the end of the third trimester of pregnancy, when all organs and tissues of the fetus are formed and X-ray examination will not harm the baby. This study is carried out with the woman lying on her back and side, which makes it possible to determine the shape of the sacrum, pubic and other bones; A special ruler is used to determine the transverse and straight dimensions of the pelvis. The fetal head is also measured, and on this basis it is judged whether its size corresponds to the size of the pelvis.
The size of the pelvis and its correspondence to the size of the head can be judged by the results of an ultrasound examination. This study allows you to measure the size of the fetal head, determine how the fetal head is located, because in cases where the head is extended, that is, the forehead or face is presented, it requires more space than in cases where the occiput is presented. Fortunately, in most cases, birth takes place in the occipital presentation.
During pregnancy, the size of the pelvis plays a role important role. Sometimes the course of labor depends on this. If the pelvic bones are narrow, complications may arise during childbirth or result in a caesarean section. A narrow pelvis is observed in approximately 3% of women during pregnancy, but it is not always an indicator for cesarean section.
When registering for pregnancy, the female pelvis is given Special attention. After measuring it, the gynecologist will be able to predict at the very beginning of pregnancy how the birth will proceed.
Distinguish anatomical And clinical narrow pelvis during pregnancy.
Anatomical narrow pelvis- discrepancy of at least one parameter by 1.5-2 cm or more from normal. It is a consequence of the influence of certain factors on the body in childhood: poor nutrition, frequent infectious diseases, lack of vitamins, hormonal disorders during puberty, congenital anomalies, injuries and fractures. Also deformation pelvic bones can occur as a result of tuberculosis, rickets, polio.
If a pregnant woman is diagnosed with 1 degree of narrowing out of 4, then giving birth naturally is quite possible. It is also possible to give birth independently with 2 degrees of contraction, but taking into account certain conditions, for example, if the fetus is not large. The remaining degrees (3 and 4) are always an indication for cesarean section.
Clinical narrow pelvis- discrepancy between the fetal head and the parameters of the mother’s pelvis, diagnosed during childbirth. IN in this case the pelvis has normal physiological parameters and shape. It is considered narrow because the fetus is quite large or is not presented correctly on the forehead or face. For this reason, the child cannot be born naturally.
Normal pelvic sizes
The pelvis is measured with a special instrument, a pelvis meter, which measures:
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The distance between the anterior upper corners of the iliac pelvic bones. Normally it is 25-26 cm. |
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The distance between the most distant points of the iliac crests. Normally it is 28-29 cm. |
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The distance between the greater trochanters of the femurs. Normally it is 31-32 cm. |
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The distance from the middle of the upper outer edge of the symphysis to the suprasacral fossa. Normally it is 20-21 cm. |
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Michaelis rhombus (lumbosacral rhombus). Normally, its diagonal value is 10 cm, vertically - 11 cm. If there is asymmetry or its parameters are smaller normal values, then this indicates incorrect structure pelvic bones. |
Additionally, it is possible to obtain data on the parameters of the pelvic bones using the following studies:
- X-ray pelviometry. Carrying out this study allowed at the end of the third trimester, when all tissues and organs of the fetus are already formed. Thanks to the procedure, you can find out the shape of the bones and sacrum, determine the direct and transverse dimensions of the pelvis, measure the fetal head and determine whether it corresponds to its parameters.
- Ultrasonography . An ultrasound can determine the correspondence of the size of the fetal head with the size of the pelvic bones. The procedure also allows you to find out the location of the fetal head, since in cases of frontal or facial presentation during childbirth, it will need more space.
- Solovyov index- measuring the circumference of a woman’s wrist joint, thanks to which you can determine the thickness of the bones and determine the direct size of the cavity of the entrance to the pelvis. Normally, the circumference of the wrist joint is 14 cm. If it is larger, then the bones are massive; if smaller, then the bones are thin. For example, with insufficient external dimensions pelvic bones and with a normal Solovyov index, the dimensions of the pelvic ring are sufficient for a child to pass through it.
Childbirth with a narrow pelvis and possible complications
In the antenatal clinic, all pregnant women with a narrow pelvis are specially registered. It is very important, in this case, to determine the date of birth, since post-term pregnancy is extremely undesirable. The woman will be admitted to the maternity hospital in 1-2 weeks. Closer to the due date, doctors will decide on the method of delivery.
During natural childbirth with a narrow pelvis, there is a high risk of developing complications in the fetus (breathing disorders, oxygen starvation, birth trauma, impaired blood circulation in the brain, fracture of the collarbone, damage to the skull bones and, worst of all, intrauterine death) and the mother (weak labor activity, premature rupture of amniotic fluid, postpartum infection, threat of uterine rupture).
Views: 28164 . Table of contents of the topic “Objective examination of a pregnant woman.”:1. Objective examination of the pregnant woman. The height of a pregnant woman. Body type of a pregnant woman. Examination of the skin. Examination of the mammary glands. Abdominal examination.
2. Examination of the internal organs of a pregnant woman.
3. Measuring the pregnant woman's abdomen. Normal size of a pregnant belly. Abdominal circumference.
4. Examination of the pregnant pelvis. Sacral rhombus (Michaelis rhombus).
5. Measuring the size of the pelvis. Transverse dimensions of the pelvis. Distantia spinarum. Distantia cristarum. Distantia trochanterica.
6. Straight pelvic size. Conjugata externa. External conjugate. The dimensions of the external conjugate are normal.
7. True conjugate. Diagonal conjugate (conjugata diagonalis). Calculation of true conjugates. The size of the true conjugate is normal.
8. Measuring the size of the pelvic outlet. Measuring the direct size of the pelvic outlet. Measuring the transverse size of the pelvic outlet.
9. Shape of the pubic angle. Measuring the shape of the pubic angle. Measuring the oblique dimensions of the pelvis.
10. Thickness of the pelvic bones. Solovyov index. Calculation of the true conjugate taking into account the Solovyov index.
Measuring the size of the pelvis. Transverse dimensions of the pelvis. Distantia spinarum. Distantia cristarum. Distantia trochanterica.
Usually measured four pelvis sizes: three transverse and one straight.
Fig.4.11a. Measuring the transverse dimensions of the pelvis. Distantia spinarum.1. Distantia spinarum- the distance between the anterosuperior iliac spines. The buttons of the pelvis are pressed to the outer edges of the feathers and non-upper spines. This size is usually 25-26 cm (Fig. 4.11, a).
Fig.4.11b. Measuring the transverse dimensions of the pelvis. Distantia cristarum.
To make it easier to study measuring the size of the pelvis, we recommend
2. Distantia cristarum- the distance between the most distant points of the iliac crests. After measuring distantia spinarum, the pelvis meter buttons are moved from the spines along the outer edge of the iliac crest until the greatest distance is determined; this distance is distantia cristarum; it averages 28-29 cm (Fig. 4.11, b)
Fig.4.11c. Measuring the transverse dimensions of the pelvis. Distantia trochanterica.3. Distantia trochanterica- the distance between the greater trochanters of the femurs. Find the most prominent points of the greater trochanters and press the buttons of the pelvis gauge to them. This size is 31-32 cm (Fig. 4 11, c)
It also matters ratio between transverse dimensions. For example, normally the difference between them is 3 cm; a difference of less than 3 cm indicates a deviation from the norm in the structure of the pelvis.
The examination plan for a pregnant woman must include measuring the pelvis. This procedure is often performed at the first appointment for every woman who consults an obstetrician-gynecologist about the desired pregnancy. The bony pelvis and the soft tissues lining it constitute the birth canal through which the baby is born. It is extremely important for doctors and women to know whether the birth canal is too small for the baby. This circumstance determines the possibility of childbirth through the natural birth canal. The results of the pelvic examination are included in the medical records. So that you can understand what is written on your exchange card, we will talk in detail about what the doctor does when measuring a pregnant woman’s pelvis.
Measuring the pelvis during pregnancy
The structure and size of the pelvis are crucial for the course and outcome of childbirth. Deviations in the structure of the pelvis, especially a decrease in its size, complicate the course of labor or present insurmountable obstacles to it.
The pelvis is examined by inspection, palpation and measurement. During the examination, attention is paid to the entire pelvic area, but special importance is attached to the sacral rhombus (Michaelis rhombus, Fig. 1), the shape of which, together with other data, allows us to judge the structure of the pelvis (Fig. 2).
Rice. 1. Sacral rhombus,or Michaelis rhombus
Rice . 2. Bonespelvis
The most important of all methods of examining the pelvis is its measurement. Knowing the size of the pelvis, one can judge the course of labor, possible complications during it, and the admissibility of spontaneous childbirth with a given shape and size of the pelvis. Most of the internal dimensions of the pelvis are not available for measurement, so the external dimensions of the pelvis are usually measured and the size and shape of the small pelvis can be approximately judged from them. The pelvis is measured with a special instrument - a pelvis meter. The pelvis meter has the shape of a compass equipped with a scale on which centimeter and half-centimeter divisions are marked. There are buttons at the ends of the branches of the tazomer; they are applied to places the distance between which is to be measured.
The following pelvic sizes are usually measured: (Latin names and abbreviations are indicated in parentheses, since the sizes are indicated that way in the exchange card.)
Distance spinarum (DistantiasplnarumD.sp.)- the distance between the anterior superior iliac spines. This size is usually 25-26 cm (Fig. 3).
Rice. 3. Measuring spinarum distance
Distance cristarum (Distantiacristarum D. Cr.)- the distance between the most distant points of the iliac crests. It averages 28-29 cm (Fig. 4).
Rice. 4. Crystarum distance measurement
Triangular distance (Distantiatrochanterica D. Tr.)- the distance between the greater trochanters of the femurs. This size is 31 -32 cm (Fig. 5).
Rice. 5. Measuring the distance of the triangular
Conjugata externaС. Ext.- external conjugate, i.e. straight pelvic size. To do this, the woman is laid on her side, the underlying leg is bent at the hip and knee joints, and the overlying leg is extended. The outer conjugate is normally 20-21 cm (Fig. 6).
Rice. 6. Measuring the outer conjugate
External conjugate is important: by its size one can judge the size true conjugates- the distance between the sacral promontory - the most protruding point inside the sacrum and the most protruding point on the inner surface of the pubic symphysis (the junction of the pubic bones). This is the smallest size inside the pelvis through which the fetal head passes during childbirth. If the true conjugate is less than 10.5 cm, then vaginal delivery may be difficult or simply impossible; in this case, a caesarean section is often performed. To determine the true conjugate, subtract 9 cm from the length of the outer conjugate. For example, if the outer conjugate is 20 cm, then the true conjugate is 11 cm; if the outer conjugate has a length of 18 cm, then the true one is 9 cm, etc. The difference between the external and true conjugates depends on the thickness of the sacrum, symphysis and soft tissues. The thickness of bones and soft tissues in women is different, so the difference between the size of the external and true conjugate does not always exactly correspond to 9 cm. The true conjugate can be more accurately determined by the diagonal conjugate.
Diagonal conjugate (conju-gatadiagonalis) is the distance from the lower edge of the symphysis to the most prominent point of the sacral promontory. The diagonal conjugate is determined during a vaginal examination of the woman (Fig. 7). The diagonal conjugate with a normal pelvis is on average 12.5-13 cm. To determine the true conjugate, 1.5-2 cm is subtracted from the size of the diagonal conjugate.
Rice. 7. Diagonal conjugate measurement
The doctor is not always able to measure the diagonal conjugate, because with normal pelvic sizes during a vaginal examination, the promontory of the sacrum is not reached by the examiner’s finger or is difficult to palpate. If during a vaginal examination the doctor does not reach the promontory, the volume of this pelvis can be considered normal. The dimensions of the pelvis and the external conjugate are measured in all pregnant women and women in labor without exception.
If during examination of a woman there is a suspicion of narrowing of the pelvic outlet, then the size of this cavity is determined. These measurements are not mandatory and are measured in a position in which the woman lies on her back, legs bent at the hip and knee joints, spread to the side and pulled up to the stomach.
Determining the shape of the pubic angle is important. With normal pelvic sizes it is 90-100°. The shape of the pubic angle is determined by the following technique. The woman lies on her back, legs bent and pulled up to her stomach. The palmar side of the thumbs is placed close to the lower edge of the symphysis. The location of the fingers allows us to judge the angle of the pubic arch.
Additional Research
If it is necessary to obtain additional data on the size of the pelvis, its correspondence to the size of the fetal head, deformations of the bones and their joints, an X-ray examination of the pelvis is performed - X-ray pelviometry. Such an examination is possible at the end of the third trimester of pregnancy, when all the organs and tissues of the fetus are formed and an x-ray examination will not harm the baby. This study is carried out with the woman lying on her back and side, which makes it possible to determine the shape of the sacrum, pubic and other bones; A special ruler is used to determine the transverse and straight dimensions of the pelvis. The fetal head is also measured, and on this basis it is judged whether its size corresponds to the size of the pelvis.
The size of the pelvis and its correspondence to the size of the head can be judged from the results ultrasound examination. This study allows you to measure the size of the fetal head, determine how the fetal head is located, because in cases where the head is extended, that is, the forehead or face is presented, it requires more space than in cases where the occiput is presented. Fortunately, in most cases, birth takes place in the occipital presentation.
When measuring externally, it is difficult to take into account the thickness of the pelvic bones. Measuring the circumference of the wrist joint of a pregnant woman with a centimeter tape is of known importance. (Soloviev index). The average value of this circumference is 14 cm. If the index is larger, it can be assumed that the bones of the pelvis are massive and the dimensions of its cavity are smaller than would be expected from measurements of a large pelvis. If the index is less than 14 cm, then we can say that the bones are thin, which means that even with small external dimensions, the dimensions of the internal cavities are sufficient for the baby to pass through them.
The time when a narrow pelvis was a kind of death sentence for a woman in labor has long gone. Modern medicine allows you to ensure a successful outcome of childbirth, regardless of the structural features of the woman’s pelvis. But for this, doctors must carry out the necessary measurements in a timely manner. And every woman should be aware of the significance of this procedure.