Obstetrics in practice. Size of true conjugates

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 tazomer 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 makes it possible 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.

The bony pelvis consists of a large and small pelvis. The border between them: behind is the sacral promontory; on the sides - innominate lines, in front - the upper part of the pubic symphysis.

The bony basis of the pelvis is made up of two pelvic bones: the sacrum and the coccyx.

The female pelvis is different from the male pelvis.

A large pelvis is not important in obstetric practice, but it is available for measurement. The shape and size of the small pelvis are judged by its size. An obstetric pelvisometer is used to measure the large pelvis.

Basic female pelvis sizes:

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

The plane of entry into the pelvis.
The plane of the wide part of the small pelvis.
The plane of the narrow part of the pelvic cavity.
The plane of exit from the pelvis.

Plane of entry into the pelvis

Borders: behind - the sacral promontory, in front - the upper edge of the pubic symphysis, on the sides - innominate lines.

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 size is 13 cm - the distance between the most distant points of the nameless lines.

Oblique dimensions are the distance from the sacroiliac joint on the left to the false protrusion on the right and vice versa - 12 cm.

The plane of the wide part of the 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.

Straight size is the distance between the gray area of the symphysis pubis and the junction of the 2nd and 3rd sacral vertebrae.

The transverse dimension is the distance between the middles 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 - the ischial spines.

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

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

Plane of exit from the pelvis

Borders: in front - the lower edge of the symphysis pubis, in the back - the apex of the coccyx, on the sides - the inner surface of the ischial tuberosities.

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

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

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

The wire axis of the pelvis is a line connecting the vertices of all straight dimensions of the 4 planes. It is not shaped like a straight line, but concave and open at the front. This is the line along which the fetus passes when it is born through the birth canal.

Pelvic conjugates

The external conjugate is 20 cm. It is measured with a pelvic meter during an 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 promontory.

The true conjugate is 11 cm. This is the distance from the upper edge of the symphysis to the sacral promontory. Not available for measurement. 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.

Along the diagonal conjugate:

1.5-2 cm is the Solovyov index.

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

If 17-18 cm, 2 cm is subtracted.

Michaelis's rhombus is a diamond-shaped formation located on the back.

It has dimensions: vertical – 11 cm and horizontal – 9 cm. In total (20 cm), giving the size of the external conjugate. Normally, the vertical size corresponds to the size of the true conjugate. The shape of the diamond and its size are used to judge the condition of the small pelvis.

In the small pelvis, the following planes are distinguished: the entrance plane, the wide part plane, the narrow part plane and the exit plane.

Entrance plane into the small pelvis passes through the upper inner edge of the pubic arch, innominate lines and the apex of the promontory. In the entrance plane, the following dimensions are distinguished.

Straight size- the shortest distance between the middle of the upper inner edge of the pubic arch and the most prominent point of the cape. This distance is called true conjugate (conjugata vera); it is equal to 11 cm. It is also customary to distinguish the anatomical conjugate - the distance from the middle of the upper edge of the pubic arch to the same point of the promontory; it is 0.2-0.3 cm longer than the true conjugate.

Transverse times measures - the distance between the most distant points of the nameless lines of opposite sides. It is equal to 13.5 cm. This size intersects the true conjugate at a right angle eccentrically, closer to the cape.

Oblique dimensions- right and left. The right oblique dimension goes from the right sacroiliac joint to the left iliopubic tubercle, and the left oblique dimension goes from the left sacroiliac joint to the right iliopubic tubercle. Each of these sizes is 12 cm.

As can be seen from the given dimensions, the entrance plane has a transverse oval shape.

Wide cha plane The cavity of the pelvic cavity passes from the front through the middle of the inner surface of the pubic arch, from the sides - through the middle of the smooth plates located under the fossae of the acetabulum (lamina acetabuli), and from the back - through the articulation between the II and III sacral vertebrae.

In the plane of the wide part, the following dimensions are distinguished.

Straight size- from the middle of the inner surface of the pubic arch to the articulation between the II and III sacral vertebrae; it is equal to 12.5 cm,

Transverse The size connecting the most distant points of the acetabular plates of both sides is 12.5 cm.

The plane of the wide part is close in shape to a circle.

The plane of the narrow part of the pelvic cavity passes in front through the lower edge of the pubic symphysis, from the sides through the ischial spines, and from behind through the sacrococcygeal joint.

In a narrow plane The parts come in the following sizes.

Direct size - from the lower edge of the pubic joint to the sacrococcygeal joint. It is 11 cm.

The transverse dimension is between the inner surface of the ischial spines. It is 10.5 cm.

The plane of exit of the small pelvis, unlike other planes of the small pelvis, consists of two planes converging at an angle along the line connecting the ischial tuberosities. It passes in front through the lower edge of the pubic arch, on the sides - through the inner surfaces of the ischial tuberosities and behind - through the apex of the coccyx.

In the exit plane, the following dimensions are distinguished.

Straight size - from the middle of the lower edge of the pubic symphysis to the tip of the coccyx. It is equal to 9.5 cm. The direct size of the outlet, due to some mobility of the coccyx, can lengthen during childbirth when the fetal head passes by 1-2 cm and reach 11.5 cm.

The transverse dimension is between the most distant points of the internal surfaces of the ischial tuberosities. It is 11 cm.

All direct dimensions of the planes of the small pelvis converge in the area of the pubic symphysis, but diverge in the area of the sacrum. The line connecting the midpoints of all direct dimensions of the pelvic planes is an arc, concave in front and curved in back. This line is called the pelvic axis. The passage of the fetus through the birth canal occurs along this line.

The angle of inclination of the pelvis - the intersection of the plane of its entrance with the plane of the horizon - when a woman is standing, can vary depending on the body type and ranges from 45 to 55°. It can be reduced if you ask a woman lying on her back to strongly pull her hips towards her stomach, which leads to the elevation of the pubis, or, conversely, it can be increased if a roll-shaped hard pillow is placed under the lower back, which will lead to a downward deviation of the pubis. A decrease in the pelvic inclination angle is also achieved if the woman takes a semi-sitting or squatting position.

Pelvic examination. In obstetrics, examination of the pelvis is very important, since the structure and size of the pelvis are 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 labor or present insurmountable obstacles to it.

The pelvis is examined by inspection, palpation and measurement. During examination, attention is paid to the entire pelvic area, but special importance is attached to the sacral rhombus (Michaelis rhombus), the shape of which, together with other data, allows us to judge the structure of the pelvis .

The sacral rhombus is a platform on the posterior surface of the sacrum: the upper corner of the rhombus forms the depression between the spinous process of the V lumbar vertebra and the beginning of the middle sacral crest; the lateral angles correspond to the posterosuperior iliac spines, the lower - to the apex of the sacrum. When examining the pelvis, the spines and crests of the iliac bones, symphysis and trochanters of the femurs are palpated.

Pelvic measurement is the most important of all pelvic examination methods. 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 pelvic meter. The tazomer 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. To measure the transverse size of the pelvic outlet, a pelvis meter with intersecting branches was designed.

When measuring the pelvis, the woman lies on her back with her stomach exposed, her legs extended and pushed together. The doctor stands to the right of the pregnant woman, facing her. The branches of the tazomer are picked up in such a way that the thumbs and forefingers hold the buttons. The graduated scale faces upward. The index fingers probe the points, the distance between which is measured by pressing the buttons of the spreader branches of the pelvis gauge against them, and the value of the desired size is marked on the scale.

Usually four sizes of the pelvis are measured: three transverse and one straight.

1. Distantia spinarum- the distance between the anterosuperior iliac spines. The buttons of the pelvis are pressed against the outer edges of the anterior-superior spines. This size is usually 25-26 cm.

2. Distantia chstarum- 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.

3. Distantia trochanterica - the distance between the greater trochanters of the femurs. The most prominent points of the greater trochanters are found and the buttons of the pelvis gauge are pressed against them. This size is 31-32 cm.

The relationship between the transverse dimensions is also important. For example, normally the difference between them is 3 cm; a difference of less than 3 a indicates a deviation from the norm in the structure of the pelvis.

4. Conjugata externa - external conjugate, those. straight pelvic size 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 button of one branch of the pelvis is installed in the middle of the upper outer edge of the symphysis, the other end is pressed against the suprasacral fossa, which is located between the spinous process of the V lumbar vertebra and the beginning of the middle sacral crest (the suprasacral fossa coincides with the upper corner of the sacral rhombus).

The superior outer edge of the symphysis is easily identified; to clarify the location above the sacral fossa, slide your fingers along the spinous processes of the lumbar vertebrae towards the sacrum; The fossa is easily determined by touch under the protrusion of the spinous process of the last lumbar vertebra. The outer diameter of the conjugate is normally 20-21 cm.

The outer conjugate is important - by its size one can judge the size of the true conjugate. 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;

The difference between the external and true conjugate depends on the thickness of the sacrum, symphysis and soft tissues. The thickness of the bones and soft tissues of women varies, 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 (conjugata diagonalis) 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, which is carried out in compliance with all the rules of asepsis and antisepsis. The II and III fingers are inserted into the vagina, the IV and V are bent, their rear rests against the perineum. The fingers inserted into the vagina are fixed at the top of the promontory, and the edge of the palm rests against the lower edge of the symphysis. After this, the second finger of the other hand marks the place of contact of the examining hand with the lower edge of the symphysis. Without removing the second finger from the intended point, the hand in the vagina is removed, and the assistant measures the distance from the top of the second finger to the point in contact with the lower edge of the symphysis with a pelvis or a centimeter tape.

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.

It is not always possible to measure the diagonal conjugate, because with normal pelvic sizes the promontory is not reached or is difficult to palpate. If the promontory cannot be reached with the end of an extended finger, the volume of this pelvis can be considered normal or close to normal. The transverse 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.

The dimensions of the pelvic outlet are determined as follows. The woman lies on her back, legs bent at the hip and knee joints, spread to the side and pulled up to the stomach.

Straight size The pelvic outlet is measured with a conventional pelvic meter. One button of the pelvis is pressed to the middle of the lower edge of the symphysis, the other to the top of the coccyx. The resulting size (11 cm) is larger than the actual one. To determine the direct size of the pelvic outlet, subtract 1.5 cm from this value (taking into account the thickness of the tissues). In a normal pelvis, the straight size is 9.5 cm. Transverse size The pelvic outlet is measured with a measuring tape or a pelvic meter with intersecting branches. The inner surfaces of the ischial tuberosities are felt and the distance between them is measured. To the resulting value you need to add 1 - 1.5 cm, taking into account the thickness of the soft tissues located between the buttons of the pelvis and the ischial tuberosities. The transverse size of the outlet of a normal pelvis is 11 cm.

Of known clinical significance is the definition shape of the pubic angle. 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.

Oblique pelvic dimensions have to be measured with a constricted pelvis. To identify pelvic asymmetry, the following oblique dimensions are measured:

1) the distance from the anterosuperior iliac spine of one side to the posterosuperior spine of the other side and vice versa;

2) the distance from the upper edge of the symphysis to the right and left posterosuperior spines;

3) the distance from the suprasacral fossa to the right or left anterosuperior spine.

The oblique dimensions of one side are compared with the corresponding oblique dimensions of the other. With a normal pelvic structure, the paired oblique dimensions are the same. A difference greater than 1 cm indicates pelvic asymmetry.

If it is necessary to obtain additional data on the size of the pelvis, in accordance with its size of the fetal head, deformations of the bones and their joints, an X-ray examination of the pelvis is performed (according to strict indications). X-ray pelviometry 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.

The head of a full-term fetus.

There are usually four pelvic sizes measured: three transverse and one straight.

Distantia spinarum— the distance between the anterosuperior iliac spines. The buttons of the pelvis are pressed to the outer edges of the anterosuperior spines. This size is usually 25 - 26 cm.

Distantia cristarum- the distance between the most distant points of the iliac crests. After measuring distantia spinarum, the buttons of the pelvis are moved from the spines along the outer edge of the iliac crest until the greatest distance is determined, this distance will be distantia cristarum, it averages 28 - 29 cm.

Distantia trochanterica- the distance between the greater trochanters of the femurs. The most prominent points of the greater trochanters are found and the buttons of the pelvis gauge are pressed against them. This size is 30 - 31 cm. Based on the size of the external dimensions, one can judge with some caution the size of the small pelvis. The relationship between the transverse dimensions is also important. For example, normally the difference between distantia spinarum and distantia cristarum is 3 cm; if the difference is smaller, this indicates a deviation from the norm in the structure of the pelvis.

Conjugata externa- external conjugate, i.e. direct size of the pelvis. 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 button of one branch of the pelvis is installed in the middle of the upper outer edge of the symphysis, the other end is pressed against the suprasacral fossa, which is located between the spinous process of the V lumbar vertebra and the beginning of the middle sacral crest (the suprasacral fossa coincides with the upper corner of the sacral rhombus).

The external conjugate is normally 20 - 21 cm. The upper outer edge of the symphysis is easily determined; to clarify the location of the suprasacral fossa, slide your fingers along the spinous processes of the lumbar vertebrae towards the sacrum; the fossa is easily determined by touch under the protrusion of the spinous process of the last lumbar vertebra.

The outer conjugate is important; its size can be used to judge the size of the true conjugate. To determine the true conjugate, subtract 9 cm from the length of the outer conjugate. For example, with an outer conjugate of 20 cm, the true conjugate is 11 cm, with an outer conjugate with a length of 18 cm, the true one is 9 cm, etc. The difference between the outer and true conjugate 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.

Diagonal conjugate (conjugata diagonalis) 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 a woman, which is performed in compliance with all the rules of asepsis and antiseptics. The II and III fingers are inserted into the vagina, the IV and V are bent, their back rests against the perineum. The fingers inserted into the vagina are fixed at the top of the promontory, and the edge of the palm rests against the lower edge of the symphysis.

After this, the second finger of the other hand marks the place of contact of the examining hand with the lower edge of the symphysis. Without removing the second finger from the intended point, the hand located in the vagina is removed and measured with a pelvis or a centimeter tape with the help of another person, the distance from the top of the third finger to the point in contact with the lower edge of the symphysis. 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.

The dimensions of the pelvic outlet are determined as follows. The woman lies on her back, legs bent at the hip and knee joints, spread to the side and pulled up to the stomach. The direct size of the pelvic outlet is measured with a conventional pelvic meter. One button of the pelvis is pressed to the middle of the lower edge of the symphysis, the other to the top of the coccyx. The resulting size (11 cm) is larger than the actual one.

To determine the direct size of the pelvic outlet, subtract 1.5 cm from this value (taking into account the thickness of the tissues). The transverse size of the pelvic outlet is measured with a measuring tape or a pelvis gauge with intersecting branches. The inner surfaces of the ischial tuberosities are felt and the distance between them is measured. To the resulting value you need to add 1 - 1.5 cm, taking into account the thickness of the soft tissues located between the buttons of the pelvis and the ischial tuberosities. Determining the shape of the pubic angle is of well-known clinical importance.

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 branches of the pubic and ischial bones, the touching ends of the fingers are pressed against the lower edge of the symphysis. The location of the fingers allows us to judge the angle of the pubic arch. The oblique dimensions of the pelvis have to be measured with a constricted pelvis.

“Obstetrics”, V.I. Bodyazhina

Special obstetric examination includes three main sections:
· external obstetric examination;
· internal obstetric examination;
· additional research methods.

External obstetric examination includes: examination, pelviometry, and after 20 weeks, measurement of the largest circumference of the abdomen, palpation of the abdomen and symphysis pubis, auscultation of fetal heart sounds.

Internal obstetric examination includes: examination of the external genitalia, examination of the cervix using speculum, vaginal examination.

External obstetric examination

Obstetric measurements

To indirectly assess the internal dimensions of the small pelvis, pelviometry is performed.

The normal values of the external dimensions of the pelvis are:
· distantia spinarum 25–26 cm;
· distantia cristarum 28–29 cm;
· distantia trochanterica 31–32 cm;
· conjugata externa 20–21 cm;
· conjugata diagonalis 12.5–13 cm.

It is most important to determine the conjugata vera (true conjugate) at the first examination, that is, the direct size of the entrance to the pelvis (normally 11–12 cm). Ultrasound measurement can provide reliable data, however, due to the insufficient prevalence of this method, indirect methods for determining the true conjugate are currently still used:

· 9 cm is subtracted from the conjugata externa value and the approximate size of the true conjugate is obtained;
· according to the vertical size of the Michaelis diamond (it corresponds to the value of the true conjugate);
· Frank's size (distance from the spinous process of the VII cervical vertebra to the middle of the jugular notch), which is equivalent to the true conjugate;
· according to the value of the diagonal conjugate - the distance from the lower edge of the pubic symphysis to the most prominent point of the sacral promontory (12.5–13 cm). Determined by vaginal examination. With normal sizes, the tazamys is unattainable. If the cape is reached, the Solovyov index is subtracted from the size of the diagonal conjugate and the size of the true conjugate is obtained.

A number of authors, based on a comparison of measurement data of the Solovyov index (1/10 of the circumference of the hand in the area of the wrist joint) and the true conjugate, propose to subtract 1/10 of the circumference of the hand from the value of the diagonal conjugate. For example, with a diagonal conjugate of 11 cm and a wrist joint circumference of 16 cm, one must subtract 1.6 - the size of the true conjugate will be 9.4 cm (the first degree of narrowing of the pelvis), with a hand circumference of 21 cm, subtract 2.1, in this case the size of the true conjugate equal to 8.9 cm (second degree of pelvic narrowing).

If one or more dimensions deviate from the specified values, it is necessary to take additional measurements of the pelvis:
· lateral conjugate - the distance between the anterior and posterior iliac spines of the same side (14–
15 cm and more); if the lateral conjugate is 12.5 cm or less, delivery is impossible;
· oblique dimensions of the small pelvis:
from the middle of the upper edge of the pubic symphysis to the posterior superior spine of both sides (17.5 cm);
from the anterior superior spine of one side to the posterior superior spine of the other side (21 cm);
from the spinous process of the V lumbar vertebra to the anterosuperior spine of each ilium (18 cm); the measured distances are compared in pairs.

The difference between the sizes of each pair of more than 1.5 cm indicates an oblique narrowing of the pelvis, which can affect the course of labor.

It is also necessary to determine the angle of inclination of the pelvis - the angle between the plane of the entrance to the pelvis and the plane of the horizon (measured with a pelvic angle gauge in a standing position); usually it is 45–55°; deviation of its value in one direction or another can adversely affect the course of labor.

The pubic angle is measured - the angle between the descending branches of the pubic bone. The pubic angle is measured with the pregnant woman in the gynecological chair, with the thumbs of both hands placed along the descending branches of the pubic bone. Normally, the pubic angle is 90–100°.

Measuring the size of the pelvic outlet is informative:
· straight size (9 cm) - between the top of the coccyx and the lower edge of the pubic symphysis. Subtract 2 cm from the resulting figure (thickness of bones and soft tissues);
· the transverse size (11 cm) is measured with a pelvic gauge with intersecting branches or a rigid ruler between the inner surfaces of the ischial tuberosities. To the resulting figure add 2 cm (thickness of soft tissues).

Using a centimeter tape, measure the abdominal circumference at the level of the navel (at the end of a normal pregnancy it is 90–100 cm) and the height of the uterine fundus (UFH) - the distance between the upper edge of the symphysis pubis and the fundus of the uterus.

At the end of pregnancy, the average length of the abdominal cavity is 36 cm. Measuring the abdomen allows the obstetrician to determine the duration of pregnancy, the approximate expected weight of the fetus (by multiplying the values of the two indicated sizes), identify a violation of fat metabolism, and suspect polyhydramnios or oligohydramnios.

Palpation

Palpation of the abdomen allows you to determine the condition of the anterior abdominal wall and muscle elasticity. After the size of the uterus increases, when external palpation becomes possible (13–15 weeks), it is possible to determine the tone of the uterus, the size of the fetus, the amount of OB, the presenting part, and then, as pregnancy progresses, the articulation of the fetus, its position, position and appearance.

When palpating the abdomen, the so-called external obstetric examination techniques (Leopold's techniques) are used:
· 1st appointment of external obstetric examination - determination of the intrauterine cavity and the part of the fetus located in the fundus.
· 2nd reception of external obstetric examination - determination of the position of the fetus, which is judged by the location of the back and small parts of the fetus (arms and legs).
· 3rd reception of external obstetric examination - determining the nature of the presenting part and its relationship to the pelvis.
· 4th reception of external obstetric examination - determination of the relationship of the presenting part with the entrance to the pelvis.

Articulation of the fetus is the relationship of the fetal limbs to the head and torso. When determining the position of the fetus (the ratio of the longitudinal axis of the fetus to the longitudinal axis of the uterus), the following positions are distinguished:
· longitudinal;
· transverse;
· oblique.

Fetal position is the relationship of the fetal back to the right or left side of the uterus. There are I (the back is facing the left side of the uterus) and II (the back of the fetus is facing the right side) positions of the fetus. Type of position - the relationship of the back of the fetus to the anterior or posterior wall of the uterus. If the back is facing anteriorly, they speak of an anterior view; if the back is facing anteriorly, they speak of a posterior view.

Fetal presentation is the relationship of the large part of the fetus (head and buttocks) to the inlet of the pelvis.

Palpation of the symphysis pubis is performed to identify the discrepancy of the symphysis pubis and symphysitis during pregnancy. Pay attention to the width of the symphysis pubis and its pain during examination.

Auscultation

Listening to the fetal heartbeat is performed with an obstetric stethoscope, starting in the second half of pregnancy (less often from 18–20 weeks). An obstetric stethoscope differs from a regular stethoscope in having a wide funnel. Fetal heart sounds are heard from the side of the abdomen where the back is facing, closer to the head. In transverse positions, the heartbeat is determined at the level of the navel, closer to the fetal head. During multiple pregnancies, fetal heartbeats are usually heard clearly in different parts of the uterus. The fetal heartbeat has three main auscultatory characteristics: frequency, rhythmicity and clarity. The normal beat frequency is 120–160 per minute.

The heartbeat should be rhythmic and clear. In addition to the obstetric stethoscope, fetal monitors based on the Doppler effect can be used to auscultate fetal heart sounds.

Internal obstetric examination

An internal obstetric examination is carried out under the following conditions: the pregnant woman should lie on her back with her legs bent at the knee and hip joints and spread apart; the woman's pelvis should be raised; the bladder and bowels are empty; The study is carried out in compliance with all rules of asepsis.

Examination of the external genitalia

When examining the external genitalia, the nature of hair growth (female or male type), the development of the labia minora and majora, the condition of the perineum (high and trough-shaped, low) are noted; the presence of pathological processes: inflammation, tumors, condylomas, fistulas, scars in the perineal area after ruptures. When examining the area of the anus, pay attention to the presence of hemorrhoids.

Spreading the labia minora with your fingers, examine the vulva and the entrance to the vagina, the condition of the external opening of the urethra, the paraurethral ducts and the outlet ducts of the large glands of the vestibule of the vagina.

Examination of the cervix using speculum

During the study, spoon-shaped or folding mirrors are used. Determine: the color of the mucous membrane of the cervix and vagina, the nature of the secretion, the size and shape of the cervix and external uterine pharynx, the presence of pathological processes on the cervix (cicatricial deformity, ectropion, ectopia, leukoplakia, polyp of the cervical canal, condylomas) and the walls of the vagina.

Obstetric vaginal examination in the first trimester of pregnancy is two-handed (vaginal-abdominal wall) (see “Diagnostics of pregnancy and determining its duration”), and in the second and third trimesters - one-handed (no need for palpation through the anterior abdominal wall).

At the beginning of the study, the condition of the perineum (its rigidity, the presence of scars) and the vagina (width and length, the condition of its walls, folding) are determined. Then the cervix is examined: its length, shape are determined (closed, slightly open, allows the tip of a finger through, passes through one finger, etc.).

On the eve of childbirth, the degree of maturity of the cervix is determined, which is an integral indicator of the body’s readiness for childbirth.

There are many different methods for assessing cervical maturity. All methods take into account the following parameters:
· consistency of the cervix;
· length of the vaginal part and cervical canal of the uterus;
· degree of patency of the cervical canal;
· location and direction of the axis of the cervix in the pelvic cavity;
· the condition of the lower segment of the uterus and the thickness of the wall of the vaginal part of the cervix.

Taking into account these signs, classifications of the degree of maturity of the cervix have been developed (Table 9-1) (Bishop E.H., G.G. Khechinashvili).

Table 9-1. Scheme for assessing cervical maturity (Bishop E.H., 1964)

With a score of 0–5 points, the cervix is considered immature; if the score is more than 10, the cervix is mature (ready for childbirth) and labor induction can be used.

Classification of cervical maturity according to G.G. Khechinashvili:

· Immature cervix - softening is noticeable only at the periphery. The cervix is dense along the cervical canal, and in some cases - in all parts. The vaginal part is preserved or slightly shortened, located sacrally. The external pharynx is closed or allows the tip of the finger to pass through, determined at a level corresponding to the middle between the upper and lower edges of the symphysis pubis.

· The ripening cervix is not completely softened; a patch of dense tissue is still noticeable along the cervical canal, especially in the area of the internal pharynx. The vaginal part of the cervix is slightly shortened; in primigravidas, the external os allows the tip of the finger to pass through. Less often, we pass the cervical canal for the finger to the internal os or with difficulty beyond the internal os. There is a difference of more than 1 cm between the length of the vaginal part of the cervix and the length of the cervical canal. A sharp transition of the cervical canal to the lower segment in the area of the internal pharynx is noticeable.

The presenting part is not clearly palpated through the fornix. The wall of the vaginal part of the cervix is still quite wide (up to 1.5 cm), the vaginal part of the cervix is located away from the wire axis of the pelvis. The external pharynx is defined at the level of the lower edge of the symphysis or slightly higher.

· The not fully ripened cervix is almost completely softened, only in the area of the internal pharynx is an area of dense tissue still visible. In all cases, the canal can be passed through the internal os for one finger, but in first-time mothers it is difficult. There is no smooth transition of the cervical canal to the lower segment. The presenting part is palpated through the arches quite clearly. The wall of the vaginal part of the cervix is noticeably thinned (up to 1 cm), and the vaginal part itself is located closer to the wire axis of the pelvis. The external pharynx is defined at the level of the lower edge of the symphysis, sometimes lower, but not reaching the level of the ischial spines.

· The mature cervix is completely softened, shortened or sharply shortened, the cervical canal freely passes one finger or more, is not curved, smoothly passes to the lower segment of the uterus in the area of the internal pharynx. The presenting part of the fetus is quite clearly palpated through the fornix. The wall of the vaginal part of the cervix is significantly thinned (up to 4–5 mm), the vaginal part is located strictly along the axis of the pelvis, the external os is defined at the level of the ischial spines.