Normal size of the small pelvis. Internal dimensions of the pelvis - obstetrics

Bone pelvis consists of a large and small pelvis. The border between them: behind - the sacral cape; from the sides - nameless lines, in front - top part pubic symphysis.

The bone base of the pelvis is made up of two pelvic bones: the sacrum and the coccyx.

The female pelvis is different from the male pelvis.

The large pelvis in obstetric practice is not important, but it is available for measurement. By its size judge the shape and size of the small pelvis. An obstetric pelvis is used to measure the large pelvis.

Main female pelvic dimensions:

In obstetric practice, the pelvis plays a fundamental role, which consists of 4 planes:

1. The plane of the entrance to the small pelvis.
2. The plane of the wide part of the small pelvis.
3. The plane of the narrow part of the pelvic cavity.
4. The plane of exit from the small pelvis.

The plane of the entrance to the small pelvis

Borders: behind - sacral cape, in front - upper edge pubic symphysis, on the sides - nameless lines.

The direct size is the distance from the sacral promontory to the upper edge of the false articulation 11 cm. The main size in obstetrics is coniugata vera.

The transverse dimension is 13 cm - the distance between the most distant points of the nameless lines.

Oblique dimensions - this is the distance from the sacroiliac joint on the left to the false ledge on the right and vice versa - 12 cm.

The plane of the wide part of the small pelvis

Borders: in front - the middle of the false articulation, behind - the junction of the 2nd and 3rd sacral vertebrae, on the sides - the middle of the acetabulum.

It has 2 sizes: straight and transverse, which are equal to each other - 12.5 cm.

The direct size is the distance between the gray hair of the pubic joint and the junctions of the 2nd and 3rd sacral vertebrae.

The transverse dimension is the distance between the midpoints of the acetabulum.

The plane of the narrow part of the pelvic cavity

Borders: in front - the lower edge of the pubic symphysis, behind - the sacrococcygeal joint, on the sides - ischial spines.

The direct size is the distance between the lower edge of the pubic joint and the sacrococcygeal joint - 11 cm.

The transverse dimension is the distance between ischial spines- 10.5 cm.

The plane of exit from the small pelvis

Borders: in front - the lower edge of the pubic joint, behind - the tip of the coccyx, on the sides - the inner surface of the ischial tuberosities.

The direct size is the distance between the lower edge of the symphysis and the tip of the coccyx. During childbirth, the head of the fetus deviates the coccyx by 1.5-2 cm, increasing its size to 11.5 cm.

Transverse size - the distance between the ischial tubercles - 11 cm.

The angle of inclination of the pelvis is the angle formed between the horizontal plane and the plane of the entrance to the small pelvis, and is 55-60 degrees.

The wire axis of the pelvis is a line connecting the vertices of all direct dimensions of 4 planes. It has the shape of not a straight line, but concave and open in front. This is the line along which the fetus passes, being born through the birth canal.

Pelvis conjugates

External conjugate - 20 cm. Measured with a tazometer during external obstetric examination.

Diagonal conjugate - 13 cm. Measured by hand during internal obstetric examination. This is the distance from the lower edge of the symphysis ( inner surface) to the sacral cape.

The true conjugate is 11 cm. This is the distance from the upper edge of the symphysis to the sacral promontory. The measurement is not available. It is calculated by the size of the outer and diagonal conjugate.

According to the external conjugate:

9 is a constant number.

20 - external conjugate.

According to the diagonal conjugate:

1.5-2 cm is the Solovyov index.

The thickness of the bone is determined along the circumference wrist joint. If it is 14-16 cm, then 1.5 cm is subtracted.

If 17-18 cm - 2 cm is subtracted.

Rhombus Michaelis - the formation, which is located on the back, has a diamond shape.

It has dimensions: vertical - 11 cm and horizontal - 9 cm. In total (20 cm) giving the size of the outer conjugate. Fine vertical dimension corresponds to the value of the true conjugate. The shape of the rhombus and its size are judged on the state of the small pelvis.

Taz adult woman consists of four bones: two pelvic (nameless), sacrum and coccyx, which are interconnected by cartilage and ligaments. In turn, the pelvic bone was formed as a result of the fusion of the ilium, pubis and ischium, at the age of 16-18 years. The female pelvis is wider and more voluminous than the male pelvis, but less deep. The presence of a normal pelvis is one of the main conditions normal flow childbirth. Various deviations in the structure of the pelvis and its symmetry can lead to a complicated course of pregnancy and impede the normal passage of the child through the birth canal or completely prevent natural childbirth.

Pelvic measurement during pregnancy

When a woman is registered for pregnancy, as well as upon admission to the maternity hospital, the doctor conducts a detailed examination and measurement of the pelvis. Pay attention to the shape of the pelvis, the symmetry of the location of anatomical landmarks (anteroposterior and posterior superior spines and ridges ilium) and sacral rhombus (Michaelis rhombus).

Rhombus Michaelis is a platform located on the back surface of the sacrum. The upper angle is in the depression between the spinous processes of the 5th lumbar vertebra and the beginning of the middle sacral crest, the lateral angles correspond to the posterior superior iliac spines, and the lower one to the apex of the sacrum. Normally, the rhombus is symmetrical, and when various options narrow pelvis changes its shape and size of the transverse and vertical diameters.

To predict the nature of childbirth highest value has a study of the size of the small pelvis. However, most internal dimensions are not available for measurement, therefore, external dimensions are usually measured and judged on the size and shape of the small pelvis. To get an idea of ​​the thickness of a woman's bones, measure the circumference of the pregnant woman's wrist joint with a centimeter tape ( Solovyov index). On average, it is 14 cm, if the value is greater, then it can be assumed that the pelvic bones are more massive, and the size of its cavities is smaller than could be expected from the external measurement of the pelvis.

To measure the pelvis, a special instrument is used - a pelvis. It has the form of a compass with a scale on which centimeter and half-centimeter divisions are applied. During the measurement, the woman lies on a couch with her stomach exposed. Usually four sizes of the pelvis are measured:

• Distantiaspinarum- the distance between the anterior superior iliac spines (the most prominent points on the anterior surface of the pelvis). Normally it is 25 - 26 cm.
• Distantiacristarum- the distance between the most distant points of the iliac crests, on average 28 - 29 cm.
• Distantiatrohanterica- distance between large skewers thigh bones, this size is 31 - 32 cm.

Important The ratio between these three dimensions is important. Normally, the difference between them is 3 cm, and a decrease in this value indicates a narrowing of the pelvis.

• Conjgataexterna, external conjugate, direct size of the pelvis - the distance between the upper edge of the pubic joint and the upper angle of the sacral rhombus, normally equal to 20 21 cm. By the size of the external conjugate, the size of the true conjugate is judged, which characterizes the direct size of the plane of entry into the small pelvis, normally it is 10-11 cm. With changes in this size, there may be an incorrect insertion of the head into the pelvic cavity and, as a result, a complicated course of childbirth. The size of the true conjugate can also be determined when vaginal examination women by measuring the diagonal conjugate, but most often with a normal size of the pelvis, the promontory of the sacrum is not achievable.

If during the examination there are suspicions of a possible narrowing of the pelvic outlet, then the doctor also measures the dimensions of this plane:

• Straight size- the distance between the middle of the lower edge of the pubic symphysis and the tip of the coccyx, 1.5 cm (approximate tissue thickness) must be subtracted from the obtained value and the result obtained is on average 9.5 cm.
• Transverse dimension- the distance between the ischial tubercles, normally it is 11 cm.

With an oblique pelvis, oblique dimensions are measured and paired distances are compared to each other to detect asymmetry.

Sometimes, to determine the true conjugate of the pelvis, the location of the fetal head, and the features of its insertion, ultrasound procedure through the front abdominal wall. Transvaginal ultrasound allows you to measure the direct and transverse dimensions of the small pelvis.

According to strict indications, if necessary, obtain Additional information about the condition of the pelvic bones, their joints, the presence of deformities, conduct x-ray examination pelvis.

During childbirth, in the process of moving through the birth canal, the child passes through four planes of the small pelvis. According to the location of the sutures on the fetal head and the bone landmarks of the woman's pelvis, the doctor determines their relative position, correct insertion and speed of advancement. This allows you to diagnose various violations and timely change the tactics of childbirth. For example, if the size of the fetal head and the woman's pelvis do not match (clinically narrow pelvis), it is not fixed in the plane of the entrance to the small pelvis, and contractions and attempts are not effective. And for a favorable outcome of childbirth for the mother and child, it is necessary to perform a Caesarean section.

wide pelvis

A wide pelvis is more common in tall large women and is not a pathology. Detected during routine examination and measurement of the pelvis. Its dimensions are 2-3 cm larger than the normal pelvis. Childbirth with a wide pelvis proceeds normally, but can be rapid. The time of passage of the child through the birth canal is reduced, in connection with this, ruptures of the cervix, vagina and perineum may be observed.

narrow pelvis

In obstetrics, two concepts are distinguished - anatomically and clinically narrow pelvis

Anatomically narrow pelvis consider the pelvis, in which all or at least one size is 1.5 - 2 cm below the norm. But it happens that even with anatomical narrowing, childbirth proceeds normally, when the child is small and his head passes through the mother's pelvis without any complications.

Clinically narrow pelvis may be at normal sizes, but if the baby is large, then there may be a discrepancy between the fetal head and the mother's pelvis. In this case, childbirth through natural birth canal can lead to serious complications of the condition of the mother and fetus, therefore, at the first sign of a discrepancy, the possibility of surgery is considered.

Reasons for the development of a narrow pelvis:

• Rickets;
• Malnutrition in childhood;
• Cerebral palsy;
• Polio;
• Congenital anomalies of the pelvis;
• Pelvic fractures;
• Tumors of the pelvis;
• Spinal deformities (kyphosis, scoliosis, spondylolisthesis, coccyx deformity);
• Diseases and dislocation of the hip joints;
• Rapid growth during puberty with an excess of androgens;
• Significant psycho-emotional and physical stress during puberty.

Varieties of a narrow pelvis:

• Relatively common forms

1. Transverse pelvis.
2. Flat pelvis:
3. Simple flat pelvis;
4. Flat rachitic pelvis;
5. Pelvis with reduction straight size wide part of the cavity.
6. General uniformly narrowed pelvis.

• Rare forms:

1. Oblique and oblique pelvis;
2. The pelvis, narrowed by exostoses, bone tumors due to fractures with displacement;
3. Other forms of the pelvis.

Additionally At present, erased forms of the narrow pelvis are more common, which presents significant difficulties in their recognition.

Pregnant women with a narrowed pelvis belong to the group high risk development of complications and antenatal clinic are on a special account. Due to the narrowing pelvis dimensions, the fetal head cannot be properly positioned and therefore often wrong positions fruit - transverse and oblique. breech presentation occurs three times more often than in pregnant women with a normal pelvis. Women with narrow pelvis recent months pregnancy due to the high standing of the bottom of the uterus, the heart is displaced and the movement of the lungs is limited, so their shortness of breath is more pronounced and lasts longer. 1 - 2 weeks before delivery, the pregnant woman is sent to the maternity hospital to clarify the diagnosis and choice rational method delivery. With a narrowing of the pelvis of the I degree and a small size of the fetus and correct insertion, childbirth can proceed normally. However, most often there are any complications (incorrect insertion of the fetus, entanglement of the umbilical cord, fetal hypoxia, preeclampsia), and then prescribe planned operation Caesarean section.

At natural childbirth a woman with a narrow pelvis should be under special control from the very beginning labor activity. If the fetal head is not pressed against the entrance to the small pelvis, but has already begun, then there may be an early outflow of amniotic fluid and prolapse of the umbilical cord, arms or legs of the fetus. It is also possible to develop various anomalies of labor activity. In such a situation, they go for an emergency operation.

Pelvic pain during pregnancy

In the second half of pregnancy, women may experience pain in the pelvis different intensity and duration. The reasons are always different, so it is very important to accurately and in detail tell the doctor about your feelings.

If the pelvic bones hurt it is most likely caused by a lack of calcium in bone tissue. The pain is usually constant, aching, does not depend on the movement and position of the body. Appoint complex preparations calcium and vitamin D.

With an increase in the size of the uterus, the ligaments that hold it begin to stretch, which can manifest itself painful sensations during walking and fetal movements. Recommended for prevention. Under the action of prolactin and relaxin, the ligaments and cartilages of the pelvis swell and soften to facilitate the passage of the fetus through the birth canal. In this regard, by the end of pregnancy, the pelvic circumference may increase by 1 - 1.5 cm, and after childbirth, when hormonal background will return to the previous level, all these changes pass. Very rarely, there is an excessive swelling of the pubic symphysis, which is manifested by arching pains in the pubic area and the inability to raise the straight leg from a lying position - this is symphysitis. This condition can also be a complication of childbirth. Treatment depends on the degree of discrepancy.

At varicose veins the veins of the vagina and labia may experience a feeling of heaviness of bursting, which is caused by stagnation of blood. For any manifestation varicose disease must be worn compression stockings or bandage your feet elastic bandages for the prevention of thromboembolic complications.

Planes and dimensions of the small pelvis. The small pelvis is bone part birth canal. Back wall The small pelvis consists of the sacrum and coccyx, the lateral ones are formed by the ischial bones, the anterior one is formed by the pubic bones and the symphysis. The posterior wall of the small pelvis is 3 times longer than the anterior one. Upper section The small pelvis is a solid, unyielding bone ring. In the lower section, the walls of the small pelvis are not solid, they contain obturator openings and ischial notches, limited by two pairs of ligaments (sacrospinous and sacrotuberous). The small pelvis has following departments: inlet, cavity and outlet. In the pelvic cavity, wide and narrow parts are distinguished (Table 5). In accordance with this, four planes of the small pelvis are distinguished: 1 - the plane of the entrance to the pelvis; 2 - the plane of the wide part of the pelvic cavity; 3 - the plane of the narrow part of the pelvic cavity; 4 - the plane of the exit of the pelvis. Table 5

c) The right and left oblique dimensions are 12-12.5 cm. The right oblique dimension is the distance from the right cross-iliac joint to the left ilio-pubic tubercle; left oblique size - from the left sacroiliac joint to the right iliac-pubic tubercle. In order to make it easier to navigate in the direction of the oblique dimensions of the pelvis in a woman in labor, M. S. Malinovsky and M. G. Kushnir proposed the following technique (Fig. 69): the hands of both hands are folded at a right angle, with the palms facing up; the ends of the fingers are brought closer to the outlet of the pelvis of the lying woman. The plane of the left hand will coincide with the left oblique size of the pelvis, the plane of the right hand with the right.

This line connecting the centers of all direct dimensions of the pelvis is called the wire axis of the pelvis. At first, it is straight, and then it bends in the pelvic cavity, corresponding to the concavity of the inner surface of the sacrum. In the direction of the wire axis of the pelvis, the fetus passes through the birth canal. Pelvic tilt. At vertical position in women, the upper edge of the symphysis is below the sacral promontory; true koiyuga-ga forms an angle with the horizon plane, which is normally equal to 55-60 °. The ratio of the plane of entry into the pelvis to the horizontal plane is called the inclination of the pelvis (Fig. 72). The degree of inclination of the pelvis depends on the characteristics of the physique.

The birth and development of man is an extraordinary miracle. A woman carries a fetus for nine months, half consisting of the genes of a man. mother organism accepts, gives nutrients, oxygen, pushing other organs, the uterus grows.

From a small organ of 5-7 centimeters, it grows five hundred times, reaches a weight of one and a half kilograms and becomes a huge home for a baby, which can withstand up to 6-7 kilograms. Let's talk about how the size of the pelvis changes and what is the norm.

Why does the doctor examine the pelvic region of pregnant women

For the normal course of pregnancy and successful labor great importance have the volume and dimensions of the pelvis of a woman. In three to six percent of pregnant women, reduced pelvic sizes are detected, which can significantly affect the process of spontaneous childbirth. naturally.

A narrow pelvis in a future woman in labor should be diagnosed by a doctor already at the time of staging expectant mother on account. To do this, the obstetrician conducts a thorough examination and makes all the necessary measurements. In accordance with the size of the pelvic bones, the methods and tactics of childbirth will be determined so that the mother and child do not develop serious complications and injuries.

Pelvic region of the female body

The structure of the pelvic region female body consists of two sections: large and small pelvis. The child in the uterus lies in the large pelvis, and by the seventh or eighth month of pregnancy, the baby moves to the opening of the small pelvis leading to the birth canal.

During the onset of contractions in the mother, the fetus gradually, with the help of various movements, enters the birth canal with its head directed to the left or to right side. Directly head as the most big organ the child must first pass through the bone frame, for this the bones are displaced / flattened. Then the pelvic bones are moved apart, providing the fetus normal appearance into the world.

The size of the pelvis in obstetrics is a serious issue, since a narrow pelvis is a problem and will not allow a woman to give birth to a child naturally. The bone frame of the birth canal will not allow the baby's head to crawl out. In this case, the woman in labor will undergo surgery C-section.

How to determine the size of the pelvis

Doctors are not interested in the size of everything, but only in the small pelvis, which is a bony birth canal. Naturally, it is technically problematic to determine its values ​​from the inside and, of course, it is very unsafe during pregnancy. Outside, the small pelvis is hidden by the femurs and muscles, so the doctor uses a special pelvis meter and a centimeter tape to measure external values. Then, according to these indicators, using special formulas, the obstetrician calculates and predicts the size of the small pelvis and bone skeleton.

Pelvic dimensions during pregnancy: normal

The parameter table will help you determine the fit pelvic bones normative indicators by measuring the distance between the bones of the pelvic region of a woman. Such measurements are carried out by a doctor using a centimeter tape. The doctor compares the taken indicators with the established norms and enters them into the patient's card.

Anatomically narrow pelvis

Based on the above measurements, the dimensions of the pelvis during pregnancy are determined. The table helps to calculate the internal dimensions of the small pelvis. In addition, they are determined in obstetrics taking into account the weight of the bones. Thus, the dimensions of the pelvis normally correspond to the indicators of 26-29-31-21-11 centimeters.

Anatomically, the pelvis is considered narrow if the main indicators are less than the norm by 1.5 or more centimeters, and the size of the true conjugate is less than 11 centimeters. However, independent natural process childbirth in a woman with a narrow pelvis can be successful if its dimensions correspond to the presentation and size of the baby.

An anatomically narrow pelvis is diagnosed even during pregnancy, while determining the parameters of deviations from the norm and the level of narrowness of the pelvic bones. The narrow pelvis is classified as flat simple or rachitic, evenly or transversely narrowed. Less common oblique pelvis, deformed, spondylolisthesis, kyphotic.

The first degree of narrowness is the most common (9-11 cm). They also distinguish the second (7-9 cm), third (5-7 cm) and fourth (less than 5 cm) degrees.

With an anatomically narrow pelvic frame of the first degree, a woman can give birth naturally with a small fetal mass. Equivalently, as in the second degree. But the diagnosis of the third or fourth degree is an indispensable indication for a planned caesarean section.

Clinically narrow pelvis

As a rule, a clinically narrow pelvis in a woman can be determined almost before the very birth with ultrasound examination or already directly in the state of childbirth. This may reveal a discrepancy between the size of the baby's head and the birth canal. This can happen to any woman in labor.

Therefore, it must be borne in mind that even with an anatomically correct size of the pelvis, with a large fetal weight (more than 4 kg), a diagnosis of "clinically narrow pelvis" can be established. More often, the identification of a clinically narrow pelvis occurs in women in labor with a post-term pregnancy, since the bones of the fetal head begin to harden, which seriously complicates the passage into the birth canal.

Diagnosis of a narrow pelvis

If the doctor revealed an anatomically narrow size of the pelvis in a future woman in labor, then two weeks before the planned birth, the woman is hospitalized.

There are many ways to diagnose the anatomically narrow size of a woman's pelvis. Among them:

• collecting an anamnesis, studying the history of childhood diseases that could lead to a violation of the size of the pelvic region;
• external examination of the shape of the abdomen, at the first gestation of the fetus, the stomach of a woman with a narrow pelvis can be sharp; in subsequent pregnancies - pendulous;
• measurement of height, body weight, hand circumference, woman's leg size;
• carrying out pelviometry - measurements by means of a tazomer;
• conducting ultrasound and vaginal examination;
• X-ray pelviometry is performed in exceptional cases with anomalies in the structure of the bones of the woman's body.

The most common method for measuring the pelvic bones of the mother and fetus of the baby is still a special diagnostic tool - the pelvis. It is a compass with a centimeter scale and allows you to measure the size of the pelvis, the length of the baby in the womb, the estimated size of the head.

The influence of a narrow pelvis on the course of pregnancy

If doctors diagnosed a narrow pelvis in a future mother, there is no reason to worry about the course of the pregnancy period. The only thing is that with an anatomically narrow pelvis, a woman visits a doctor more often. With this feature, it is recommended to more carefully prepare for delivery.

However, in rare cases with a narrow pelvis, there are complications in the last three months of pregnancy, which is revealed in the wrong presentation of the baby. Due to the fact that the fetal head is not pressed against the hole in the narrow pelvis, the mother may experience shortness of breath.

During this period, the pregnant woman must strictly follow the doctor's advice on balanced diet and rational diet. Overweight body can lead to negative impact on the condition of the pelvis and the development of the baby.

Narrow pelvis and childbirth

When diagnosing the narrow size of the pelvis, labor activity will depend on the professionalism of obstetricians and the behavior of the woman herself. Although theoretically, if the pelvic dimensions deviate from the norm, a caesarean section is inevitable, statistics show that a woman can give birth herself. Although in the process of labor activity there is a risk of complications for both the mother and the child.

Usually, a woman with a narrow pelvis has a premature pouring of amniotic fluid, a very weak labor activity is observed, so the time for the course of labor increases. A prolapse of the umbilical cord of the fetus may occur, rupture of the tissues of the uterus is more common.

The baby increases the risk of hypoxia, cerebrovascular accident, possible damage to the skull.

The actions of doctors during the course of childbirth

From the doctor in the management of childbirth of a woman in labor with a narrow pelvis, a lot of experience and optimal work tactics are required. Childbirth is carried out under careful monitoring of the condition of the child and uterine contraction using cardiotocographs. A woman in labor is injected with drugs that improve blood circulation in the uterus and placenta.

It is necessary, if possible, for a long time preserve integrity amniotic sac. Therefore, a woman must comply bed rest, it is better to lie down on the side where the deviated head is located, or where the child's back is facing.

To prevent weak labor activity, the mother is prescribed vitamins, glucose, painkillers and antispasmodic drugs. If a woman has difficulty urinating, a catheter is used.

After the discharge of the waters, a vaginal examination is done. This is how a prolapsed umbilical cord loop is diagnosed. Often, during childbirth, women with a narrow pelvis, doctors resort to the procedure of dissecting the perineum. After the birth of a child, to avoid bleeding, mothers are given drugs to activate uterine contractions.

Remember, the dimensions of the pelvis during pregnancy, the norm (table above) of which is 26-29-31-21-11 centimeters. However, despite possible risks, the main thing for a woman is to set herself up for positive result and find an experienced doctor whom she can completely trust. And then nothing will become an obstacle for a happy meeting between the mother and the newborn baby.

The table will help every woman planning a pregnancy and already expecting a baby to independently determine the size of the pelvis.

The plan of examination of a pregnant woman necessarily includes a measurement of the pelvis. This procedure is often carried out at the first appointment for every woman who has turned to an obstetrician-gynecologist about a desired pregnancy. Bone pelvis and soft tissues lining it are the birth canal through which the baby is born. It is extremely important for doctors and a woman to know if the birth canal is small for a baby. This circumstance determines the possibility of childbirth through the natural birth canal. The results of the pelvic exam are entered into 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 the pelvis of a pregnant woman.

Pelvic measurement 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 childbirth or present insurmountable obstacles for them.

The study of the pelvis is carried out by inspection, palpation and measurement. On examination, attention is paid to the entire pelvic region, but special importance is attached to the sacral rhombus (Michaelis rhombus, Fig. 1), the shape of which, in combination with other data, allows one to judge the structure of the pelvis (Fig. 2).

Rice. 1. sacral rhombus,or the Michaelis rhombus

Rice . 2. Bonespelvis

Most importance of all methods of pelvic examination has its measurement. Knowing the size of the pelvis, one can judge the course of childbirth, about possible complications with them, on 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, therefore, the external dimensions of the pelvis are usually measured and they are used to approximately judge the size and shape of the small pelvis. The pelvis is measured with a special instrument - a pelvis meter. The tazomer has the form of a compass, equipped with a scale on which centimeter and half-centimeter divisions are applied. At the ends of the branches of the tazomer there are buttons; they are applied to the places, the distance between which is to be measured.

The following pelvic sizes are usually measured: (In parentheses are indicated Latin names and abbreviations, since the sizes are indicated in the exchange card in this way.)

Distant spinarum (Distantiasplnarum D.sp.)- the distance between the anterior-superior iliac spines. This size is usually 25-26 cm (Fig. 3).

Rice. 3. Measuring the spinarum distance

Distantia cristarum (Distantiacristarum D. Cr.)- the distance between the most distant points of the iliac crests. It averages 28-29 cm (Fig. 4).

Rice. 4. Measuring the distance of the cristarum

Trianteric distance (DistantiatrochantericaD. Tr.)- the distance between the greater trochanters of the femur. This size is 31 -32 cm (Fig. 5).

Rice. 5. Measuring the distance of the triangular

Krnjugata externa (Conjugata externa C. Ext.)- external conjugate, i.e. straight size of the pelvis. 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 pulled out. The outer conjugate is normally 20–21 cm (Fig. 6).

Rice. 6. Measurement of external conjugates

External conjugate is important: by its value one can judge the size true conjugate- the distance between the sacral cape - 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). it smallest size inside the pelvis through which the fetal head passes during childbirth. If the true conjugate is less than 10.5 cm, then childbirth through the natural birth canal may be difficult or simply impossible; in this case, a caesarean section is often performed. To determine the true conjugate, 9 cm is subtracted 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 is 18 cm long, then the true conjugate is 9 cm, and so on. The difference between outdoor and true conjugates depends on the thickness of the sacrum, symphysis and soft tissues. The thickness of the bones and soft tissues in women is different, so the difference between the size of the outer 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) called the distance from the lower edge of the symphysis to the most prominent point of the promontory of the sacrum. The diagonal conjugate is determined during a vaginal examination of a woman (Fig. 7). Diagonal conjugate at normal pelvis equals an average of 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 a normal size of the pelvis during a vaginal examination, the cape of the sacrum is not reached by the researcher's finger or is palpated with difficulty. If, during a vaginal examination, the doctor does not reach the cape, 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 the examination of a woman there is a suspicion of a narrowing of the pelvic outlet, then the dimensions of this cavity are determined. These measurements are not mandatory, and they are measured in a position in which the woman lies on her back, her legs are bent at the hips and knee joints, divorced to the side and pulled up to the stomach.

The definition of the shape of the pubic angle is important. With normal pelvic dimensions, it is 90-100 °. The shape of the pubic angle is determined next trick. The woman lies on her back, her legs are bent and pulled up to her stomach. Palmar side thumbs applied close to the lower edge of the symphysis. The location of the fingers allows you to judge the magnitude of the angle of the pubic arch.

Additional Research

If necessary, to obtain additional data on the size of the pelvis, its compliance with the size of the fetal head, deformities 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 the organs and tissues of the fetus are formed and an X-ray examination will not harm the baby. This study is carried out in the position of a woman lying on her back and on her side, which allows you to establish the shape of the sacrum, pubic and other bones; a special ruler determines the transverse and direct dimensions of the pelvis. The head of the fetus is also measured, and on this basis it is judged that 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 ultrasound research. 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 unbent, that is, the forehead or face is present, then it needs more space than in cases where the occiput is present. Fortunately, in most cases, childbirth takes place in the occipital presentation.

With external pelvic measurement, it is difficult to take into account the thickness of the pelvic bones. Of known importance is the measurement of the circumference of the wrist joint of a pregnant woman with a centimeter tape (Soloviev index). The average value of this circumference is 14 cm. If the index is larger, it can be assumed that the pelvic bones are massive and the dimensions of its cavity are smaller than would be expected from the measurements of the 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.

A long time ago, the time when a narrow pelvis was a kind of sentence for a woman in labor is gone. modern medicine allows you to ensure a successful outcome of childbirth, regardless of the structural features of the pelvis of a woman. But for this, doctors must take the necessary measurements in a timely manner. And every woman should be aware of the significance of this procedure.