Narrow pelvis in pregnant women. Features of the mechanism of childbirth in various forms of a narrow pelvis

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. The mother's body takes it, 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 activity, the volume and size of the woman's pelvis are of great importance. In three to six percent of pregnant women, reduced pelvic sizes are detected, which can significantly affect the process of independent childbirth in a natural way.

A narrow pelvis in a future woman in labor should be diagnosed by a doctor already during the registration of the expectant mother. 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 have serious complications and injuries.

Pelvic region of the female body

By structure, the pelvic region of the female body consists of two sections: the 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 labor in the mother, the fetus gradually, with the help of various movements, enters the birth canal with its head directed to the left or right side. The head itself, as the largest organ of 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 with a normal birth.

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 a caesarean 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 determine the compliance of the pelvic bones with 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, an independent natural process of 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 an ultrasound examination, or already directly in the very 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 in case of 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, a pregnant woman must strictly follow the doctor's advice on a balanced diet and a rational diet. Excess body weight can lead to a 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, to maintain the integrity of the amniotic sac for a long time. Therefore, a woman should observe bed rest, it is better to lie down on the side where the deviated head is located, or where the back of the child is facing.

To prevent weak labor, the mother is prescribed vitamins, glucose, painkillers and antispasmodics. 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 the possible risks, the main thing for a woman is to set herself up for a positive result and find an experienced doctor whom she can fully 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.

Update: October 2018

The narrow pelvis is rightfully considered one of the difficult and complex sections in obstetrics, since this pathology is fraught with the development of various complications in childbirth, especially if they are not managed correctly. According to statistics, anatomical narrowing of the pelvis occurs in 1–7.7%, and during childbirth such a pelvis becomes clinically narrow in 30%. The total number of all births accounts for 1.7% of clinically narrow pelvises.

The concept of "narrow pelvis"

In the straining period, when the fetus is expelled from the uterus, it must overcome the bone ring of the birth canal, that is, the small pelvis. The pelvis consists of 4 bones: 2 pelvic, formed by the iliac, pubic and ischial bones, the sacrum and the coccyx. These bones are in contact with each other with the help of cartilage and ligaments. In women, the pelvis, unlike men, is wider and more voluminous, but has less depth. Normal parameters of the pelvis play an important role in the physiological, without complications, during childbirth. In the presence of deviations in the configuration and symmetry of the pelvis and a decrease in size, the bone pelvis acts as an obstacle to overcoming its fetal head.

In practical terms, the narrow pelvis is divided into 2 types:

anatomically narrow pelvis, which is characterized by a decrease in one / several sizes by 2 cm or more;
a clinically narrow pelvis develops when there is a discrepancy between the size of the child’s head and the anatomical dimensions of the woman’s pelvis during childbirth (but even in the case of anatomic narrowing of the pelvis during childbirth, it is not always possible to develop a functionally narrow pelvis, for example, if the fetus is small, and vice versa, with normal anatomical parameters pelvis and a large baby, the occurrence of a clinically narrow pelvis is likely).

The reasons

The reasons for the formation of a narrow pelvis differ in its anatomical narrowing or the occurrence of disproportion in the size of the baby's head and the pelvic dimensions of the mother.

Etiology of the anatomically narrowed pelvis

The following factors can provoke the formation of an anatomically narrowed pelvis:

disruptions in menstrual function, violation of childbearing function, late onset of menstruation;
neuroendocrine pathology;
frequent colds and excessive physical activity in adolescence;
malnutrition, heavy physical work in childhood.

Anatomical narrowing of the pelvis is caused by the following reasons:

infantilism, both general and sexual;
lag in sexual development;
rickets;
osteomalacia, bone tuberculosis and bone tumors;
fractures of the pelvic bones;
curvature of the spine (lordosis and kyphosis, scoliosis and fractures of the coccyx);
cerebral palsy;
features of the constitution and heredity;
polio;
exostoses and tumors of the pelvis;
damaging factors in the antenatal period;
acceleration (rapid growth of the body in length and at the same time slowing down the increase in transverse pelvic dimensions);
stressful situations and psycho-emotional stress that contribute to the emergence of "compensatory hyperfunction of the body", which forms a transversely narrowed pelvis;
professional sports (gymnastics, skiing, swimming);
disturbed mineral metabolism;
hypo- and hyperestrogenism, androgen excess;
dislocations of the hip joints.

Etiology of a functionally narrow pelvis

The disproportion in childbirth between the baby's head and the maternal pelvis is caused by:

anatomical narrowing of the pelvis;
large size and weight of the fruit;
difficulties in the configuration of the cranial bones of the fetus (true overbearing);
incorrect position of the future baby;
pathological insertion of the head (asynclitism, frontal insertion, etc.);
neoplasms of the uterus and ovaries;
narrowing (atresia) of the vagina;
breech presentation (rare).

Childbirth, complicated by a clinically narrow pelvis, in 9-50% ends with a caesarean section.

Narrow pelvis: varieties

There are many classifications of anatomically narrowed pelvis. Often in obstetric literature there is a classification based on morphological signs:

Gynecoid type

It makes up 55% of the total number of pelvises and is a normal female pelvis. The body type of the expectant mother is female, she has a thin neck and waist, and her hips are quite wide, weight, height are within the average.

android pelvis

It occurs in 20% and is a pelvis of the male type. A woman has a masculine physique, against the background of broad shoulders and narrow hips, there is a thick neck and a vague waist.

Anthropoid pelvis

It is 22% and is inherent in primates. This form is distinguished by an increase in the direct size of the entrance and its significant excess of the transverse size. Women with such a pelvis are characterized by high growth and leanness, the shoulders are quite wide, and the waist with hips is narrow, and the legs are elongated and thin.

Platypeloid pelvis

It is similar in shape to a flat pelvis, observed in 3% of cases. Women with a similar pelvis are tall and thin, underdeveloped muscles and reduced skin elasticity.

Narrowed pelvis: forms

The classification of the narrow pelvis proposed by Krassovsky:

Common forms

generally uniformly narrowed pelvis (ORST) is the most common type and is observed in 40-50% of all pelvises;
transversely narrowed pelvis (Robertovsky);
flat pelvis, is 37%;
- simple flat (Deventrovksy);
- flat rachitic;
- pelvis with a reduced wide part of the pelvic cavity.

Forms that are rare

oblique and oblique;
deformation of the pelvis with bone tumors, exostoses and fractures;
other forms:
- common flat;
- funnel-shaped;
- kyphotic form;
- spondylolisthesis form;
- osteomalacic;
- assimilation.

Degrees of contraction

Classification based on the degree of narrowing proposed by Palmov:

According to the length of the true conjugate (norm 11 cm) and refers to ORST and a flat pelvis:
- 1 st. - less than 11 cm and not shorter than 9 cm;
- 2 tbsp. - indicators of the true conjugate 9 - 7.5 cm;
- 3 art. - the length of the true conjugate 7.5 - 6.5 cm;
- 4 tbsp. - shorter than 6.5 cm, which is called "absolutely narrow pelvis".
By the size of the transverse diameter of the entrance to the small pelvis (normal dimensions 12.5 - 13 cm) and refers to the transversely narrowed pelvis:
- 1 st. - transverse diameter of the inlet within 12.4 - 11.5;
- 2 tbsp. - the value of the transverse diameter of the inlet is 11.4 - 10.5;
- 3 art. – transverse diameter shorter than 10.5.
According to the size of the direct diameter of the wide part of the pelvic cavity (normally 12.5 cm):
- 1 st. - diameter 12.4 - 11.5;
- 2 tbsp. – diameter less than 11.5.

Dimensions of the anatomically narrowed pelvis of different shapes

Narrow pelvis: dimensions (table, in cm)

Sizes Shape of the pelvis
	normal	transversely narrowed	ORST	flat-rachitic	simple flat
outdoor	25/26 – 28/29 – 30/31	24 – 26 – 29	24 – 26 – 28	26 – 26 – 31	26 – 29 – 30
External conjugate	20 – 21	20 – 21	18	17	18
Diagonal conjugate	13	13	11	10	11
True conjugate	11	11 – 11,5	9	8	9
Rhombus of Michaelis:
vertical diagonal	11	11	Under 11	Less than 9	Less than 9
Horizontal Diagonal	10 — 11	Less than 10	Less than 10	Less than 10	Less than 10
Exit plane:
straight	9,5	9,5	Less than 9.5	9,5	Less than 9.5
transverse side conjugate
Differential criterion	Missing	Shortening of transverse dimensions	Uniform reduction of all parameters by 1.5 cm or more	Reducing the direct size of the plane of entry into the pelvis	Reducing the direct dimensions of all planes

Diagnostics

The narrowed pelvis is assessed and diagnosed in the antenatal clinic, on the day the pregnant woman is registered. To identify a narrow pelvis during pregnancy, the doctor examines the history, conducts an objective study, which includes anthropometry, examination of the body, palpation of the pelvic bones and uterus, measurement of the pelvis and vaginal examination. If necessary, special methods are prescribed: X-ray pelviometry and ultrasound scanning.

Anamnesis

It is very important to pay attention to the diseases and living conditions of a pregnant woman in childhood and adolescence (rickets and polio, osteomyelitis and bone tuberculosis, hormonal imbalance, poor nutrition and hard physical work, intense sports, injuries and chronic pathology). Obstetric anamnesis data are essential:

How did previous births go?
why an operative delivery was performed, whether the newborn had craniocerebral injuries;
whether there was a stillbirth or death of the child in the neonatal period.

Objective research

Anthropometry

Low growth (145 cm or less) indicates, as a rule, a narrowed pelvis. But narrowing of the pelvis (transversely narrowed) is also possible in tall women.

Evaluated: gait, physique, silhouette

It has been proven that in the case of a strong protrusion of the abdomen forward, the center of the upper half of the body shifts backwards in order to maintain balance, and the lower back moves forward, thereby increasing the lumbar lordosis and the angle of the pelvis.

Assessing the shape of the abdomen

It is known that in a primiparous pregnant woman, the elastic abdominal wall and the abdomen acquire a pointed shape. A multiparous belly is pendulous, since the head is not inserted into the entrance of a narrow pelvis at the end of the gestation period, and the uterine fundus is high, while the uterus itself deviates from the hypochondrium upward and forward.

Identification of signs of sexual infantilism or virilization.
Inspection and palpation of the Michaelis rhombus

Rhombus Michaelis consists of the following anatomical formations:

above - the lower border of the 5th lumbar vertebra;
below - the top of the sacrum;
on the sides - the posterior upper protrusions (awns) of the ilium.

Pelvic palpation

On palpation of the iliac bones, their sloping, contours and location are revealed. On palpation of the trochanters (large trochanters of the femur), an oblique pelvis can be diagnosed if they are deformed and stand at different levels.

Vaginal examination

It makes it possible to determine the capacity of the pelvis, examine and evaluate the shape of the sacrum, the depth of the sacral cavity, whether there are bony protrusions, deformation of the lateral pelvic walls, measure the height of the symphysis and the diagonal conjugate.

Pelvis measurement

Main measurements:

Distantia spinarum - a segment between the anterior superior projections of the ilium. Norm 25 - 26 cm.
Distantia cristarum - the segment between the most distant places of the iliac crests. Norm 28 - 29 cm.
Distantia trohanterica - a segment between the skewers of the thigh bones, the norm is 31 - 32 cm.
External conjugate - the distance is measured, which starts from the upper edge of the womb and ends with the upper corner of the Michaelis rhombus. The norm is at least 20 cm.
Measurement of the Michaelis rhombus (vertical diagonal 11 cm, horizontal diagonal 10 cm). The asymmetry of the rhombus indicates a curvature of the pelvis or spinal column.
Solovyov's index - the circumference of the wrist is measured at the level of the prominent condyles of the forearm. With the help of this index, the thickness of the bones is assessed: a small index indicates the thinness of the bones, and, consequently, a greater capacity of the pelvis. Norm 14.5 - 15 cm.
Determination of the lonosacral size (a segment is measured from the middle of the symphysis to the point where the 2nd and 3rd sacral vertebrae meet). Norm 21.8 cm.
The pubic angle is measured (normally 90 degrees).
The height of the pubic joint is determined
The uterus is measured (coolant and VDM) to determine the estimated weight of the fetus.

Additional measurements:

measure the angle of the pelvis;
measure the exit of the pelvis;
if asymmetry of the pelvis is suspected, oblique dimensions and the lateral Kerner conjugate are determined.

Special research methods

X-ray pelviometry

It is allowed to conduct an X-ray examination after 37 weeks and during childbirth. With its help, the structure of the pelvic walls, the shape of the entrance, the degree of inclination of the pelvic walls, the features of the ischial bones, the severity of the sacral curvature, the shape and size of the pubic arch are determined. Also, this method provides an opportunity to find out all the diameters of the pelvis, bone tumors and fractures, the size of the child's head and its position in relation to the pelvic planes.

ultrasound

It makes it possible to determine the true conjugate, the localization of the head and its dimensions, to evaluate the features of inserting the head. Using a transvaginal probe, all pelvic diameters are determined.

How to Calculate the True Conjugate

The following methods are used:

subtract 9 from the size of the outer conjugate (normally not less than 11 cm);
1.5 - 2 cm is subtracted from the value of the diagonal conjugate (if the Solovyov index is 14 - 16 cm or less, subtract 1.5, if the Solovyov index is more than 16, subtract 2);
according to the Michaelis rhombus: its vertical size corresponds to the indicator of the true conjugate;
according to X-ray pelviometry;
according to ultrasound examination of the pelvis.

How is the pregnancy

In the first half of the period of gestation, complications with a narrowed pelvis are not observed. The nature of the course of the second half of gestation is affected by the underlying disease, which led to the formation of a narrow pelvis, in addition, extragenital pathology and emerging complications (preeclampsia, intrauterine infection, and others) affect. Pregnant girls with a narrow pelvis are characterized by:

the formation of a pointed abdomen in primiparous and sagging in multiparous, which provokes asynclitic insertion of the head during childbirth;
the risk of preterm birth increases;
excessive fetal mobility, which contributes to incorrect positions of the fetus, breech presentation and extensor presentation;
often pregnancy is complicated by premature outflow of water due to the lack of a contact belt with a high standing head;
high standing of the head due to the impossibility of inserting it into the pelvis, which causes a high standing of the uterine fundus and diaphragm and leads to increased heart rate, shortness of breath and fatigue.

Management of pregnant women

All future mothers with a narrow pelvis are registered with an obstetrician-gynecologist. A couple of weeks before the birth, a woman is hospitalized in the antenatal department in a planned manner, where the gestational age is specified, the estimated weight of the fetus is calculated, the pelvis is re-measured, the position / presentation of the fetus, its condition is clarified, and the issue of choosing a method of delivery is being decided (a birth management plan is being developed).

The method of delivery is determined on the basis of anamnestic data, the anatomical form of the narrowing of the pelvis and the degree, the estimated weight of the child and other complications of gestation. Physiological delivery can be performed in case of premature pregnancy, 1st degree of narrowing and normal size of the child, mature cervix and in the absence of a burdened obstetric history.

A planned caesarean section is performed in the presence of the following indications:

a combination of 1 - 2 degrees of narrowing and a large fetus, breech presentation, an anomaly in the position of the fetus, post-term pregnancy;
"old" primiparous, the presence of stillbirth in previous births or complicated births and the birth of a fetus with a birth injury;
a combination of a narrow pelvis and other obstetric pathology that requires operative delivery;
3 - 4 degree of narrowed pelvis (rare today).

Pregnancy and pelvic pain

Pain in the pelvic bones appears after 20 weeks and is due to various reasons:

lack of calcium

Pain is constant and aching, not associated with movement or change in body position. It is recommended to take calcium supplements in combination with vitamin D.

Sprain of the uterine ligaments and divergence of the pelvic bones

The larger the size of the uterus, the stronger the tension of the uterine ligaments that hold it, which is manifested by pain and discomfort when walking and moving the child. This is caused by prolactin and relaxin, under the influence of which the ligaments and pelvic cartilages swell and soften to "soften" the passage of the child through the bone ring. A bandage should be worn to relieve pain.

Divergence of the pubic joint

Too much swelling of the symphysis (a rare pathology) is accompanied by arching pain in the pubis, and it is also impossible to raise the straight leg in a horizontal position. This pathology is called symphysitis, which is accompanied by a divergence of the pubic joint. Effective surgical treatment, which is carried out after childbirth.

The course of childbirth

To date, the tactics of childbirth with a narrow pelvis provides for a significant increase in indications for abdominal delivery, both planned and emergency in case of complications. Conducting the birth process through the natural birth canal is a difficult task, since the outcome can be both favorable and unfavorable for the woman and the child. In cases of 3-4 degrees of narrowing, the birth of a live and full-term fetus is impossible - a planned operation is performed. If the pelvis is narrowed to 1 and 2 degrees, the successful completion of childbirth depends on the indicators of the baby's head, its ability to be configured, the nature of the insertion of the head and the intensity of labor activity.

What are the complications of a narrow pelvis during childbirth?

First period

During the period of disclosure of the uterine pharynx, childbirth can be complicated:

weakness of tribal forces (10 - 38%);
early outflow of amniotic fluid;
prolapse of the umbilical cord / small parts of the baby;
oxygen starvation of the fetus.

Second period

During the period of expulsion of the fetus, the following complications may develop:

the emergence of a secondary weakness of tribal forces;
intrauterine hypoxia;
the threat of uterine rupture;
necrosis of the tissues of the birth canal with the formation of fistulas;
damage to the pubic joint;
damage to the pelvic nerve plexuses.

Third period

The last period of childbirth, as well as the early postpartum period, is fraught with the occurrence of bleeding due to the long course of labor and the anhydrous period.

Birth management

Today, the most reasonable tactic of childbirth in the described pathology is recognized as active-expectant. Moreover, the tactics of childbirth should be individual and take into account not only the results of an objective study of the woman in labor, the degree of narrowing of the pelvis, but also the prognosis for the woman and the child. The birth plan should include the following items:

bed rest, which prevents early discharge of water (the position of the woman should be on the side to which the back of the fetus is adjacent);
prevention of weakness of tribal forces;
prevention of intrauterine starvation of the fetus;
prevention of infectious complications;
identification of signs of clinical inconsistency;
preventive measures for subsequent and early postpartum hemorrhage;
caesarean section (if indicated) with a live fetus;
fruit-destroying operation in case of fetal death.

In childbirth, they control discharge from the genital tract (mucous, water leakage or bloody), the condition of the vulva (swelling), urination. In case of urinary retention, bladder catheterization is performed, but it should be remembered that this symptom may also indicate a disproportion in the pelvic dimensions of the woman in labor and the baby's head.

The most common complication of childbirth with a narrowed pelvis is premature outflow of water. If an “immature” cervix is detected, then operative delivery is performed. In the case of a “mature” cervix, labor induction is indicated (if the estimated fetal weight is not more than 3600 g and there is 1 degree of narrowing).

In the period of contractions, an energy background is created to prevent their weakness, the woman in labor is provided with medical sleep-rest in a timely manner. In the process of evaluating the effectiveness of labor, the doctor must control not only the dynamics of the opening of the cervix, but also how the head moves along the birth canal.

Rhodostimulation should be carried out with caution, and its duration should not exceed 3 hours (if there is no effect, a caesarean section is performed). In addition, in the first period, antispasmodics are necessarily introduced (every 4 hours), the Nikolaev triad (prevention of hypoxia) is performed, and antibiotics are prescribed with an increasing anhydrous interval.

The period of exile is complicated by the development of secondary weakness, intrauterine hypoxia of the baby, and prolonged standing of the baby's head in the birth canal provokes the formation of fistulas. Therefore, an episiotomy is performed and the bladder is emptied in a timely manner.

Disproportion of the head and pelvis of the woman in labor

The occurrence of a clinically narrow pelvis is mainly promoted by:

a slight degree of narrowing and a large baby;
unsuccessful insertion of the head or incorrect presentation of the fetus;
large fetal head with normal pelvic dimensions;
abnormal forms of narrowing of the pelvis.

During childbirth, a functional assessment of the pelvis is mandatory, which includes:

determination of the features of insertion and assessment of the biomechanism of labor in case of identified insertion;
head configuration is evaluated;
diagnosis of a birth tumor on the soft tissues of the head, the speed of its appearance and growth;
identification of signs of Vasten and Zangheimester (assessed after the outflow of waters).

Signs of a clinically narrow pelvis are as follows:

the biomechanism of childbirth is violated, that is, it does not correspond to this type of narrowing of the pelvis;
the head of the fetus does not advance, although the uterine os is fully opened, the waters have receded, and the contractions are of sufficient strength;
the appearance of attempts with the head of the child pressed to the entrance to the pelvis;
symptoms of pressing soft tissues and urea (swelling of the cervix and vulva, urinary retention, blood is detected in the urine);
positive signs of Vasten, Zangheimester;
a clinic of the threat of uterine rupture appears;
protracted course of the first period;
significant head configuration;
early or premature outpouring of waters.

Vasten's sign is determined by touch (the ratio of the baby's head and the entrance to the pelvis is found out). A negative symptom of Vasten is the condition when the head is inserted into the small pelvis, located below the pubic joint (the doctor's palm fell below the womb). The symptom is flush - the palm of the obstetrician lies at the level of the womb (the head and symphysis are in the same plane). A positive sign is that the doctor's palm is above the symphysis (the head is above the womb). In the case of a negative sign, childbirth ends on its own (the head and pelvic dimensions correspond to each other). With a symptom level, independent childbirth is possible, provided that labor is effective and the head is adequately configured. In the case of a positive sign, independent childbirth is impossible.

Kalganova proposed to distinguish 3 degrees of discrepancy between the pelvic dimensions and the head of the child:

1 st. or relative mismatch

The correct insertion of the head and its good configuration are noted. The contractions are of sufficient strength and duration, but the opening of the cervix and the advancement of the head are slowed down, in addition, the water leaves untimely. Urination is difficult, but Vasten's sign is negative. Possible independent completion of childbirth.

2 tbsp. or significant non-compliance

The biomechanism of childbirth and the insertion of the head do not correspond to normal ones, the head is sharply configured and stays in the same plane for a long time. Anomalies of generic forces (discoordination or weakness), urinary retention join. Symptom Vasten flush.

3 art. or absolute mismatch

Attempts appear prematurely against the background of the lack of forward movement of the head, despite good contractions and full opening. The birth tumor is rapidly increasing, there are signs of pressing the urea, a clinic of the threat of uterine rupture appears. A positive sign of Vasten is diagnosed.

The second and third degrees of discrepancy serve as an indication for immediate operative delivery.

Case Study

A 20-year-old primipara was delivered to the maternity ward with complaints of contractions for 2 hours. There was no outflow of water. The condition of the woman in labor is satisfactory, pelvic dimensions: 24.5 - 26 - 29 - 20, coolant - 103 cm, the height of the uterine fundus is 39 cm. The fetus is located longitudinally, the head is pressed to the entrance. Auscultatory: the fetal heartbeat is clear, does not suffer. Contractions of good strength and duration. The estimated weight of the child is 4000 gr.

When conducting a vaginal examination, it was revealed: the cervix is smoothed, has thin and extensible edges, the opening is 4 cm. The water is whole, the fetal bladder is functioning. The head is pressed to the entrance. The cape is not available. Diagnosis: Pregnancy 38 weeks. 1 period 1 first term delivery. Large fruit. Transversely narrowed pelvis 1 degree.

After 6 hours of active contractions, a second vaginal examination was performed: the cervix was dilated to 6 cm, there was no amniotic sac. The head is pressed to the entrance with an arrow-shaped suture in a direct size, a small fontanel is anterior.

Diagnosis: Pregnancy 38 weeks. 1 period 1 birth at term. Transversely narrowed pelvis 1 degree. Large fruit. High straight standing swept seam.

It was decided to end the delivery by surgery (incorrect insertion, narrowing of the pelvis, large fetus). The caesarean section passed without complications, the fetus weighing 4300 g was extracted.

During pregnancy, the size of the pelvis plays an important role. Sometimes the course of childbirth depends on this. If the pelvic bones are narrow, then complications may occur during childbirth or they may end in a caesarean section. A narrow pelvis is observed in about 3% of women during pregnancy, but it is not always an indicator for caesarean.

When registering for pregnancy, the female pelvis is given special attention. After measuring it, the gynecologist at the very beginning of pregnancy will be able to guess 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 impact of certain factors on the body in childhood: malnutrition, frequent infectious diseases, lack of vitamins, hormonal disorders during puberty, congenital anomalies, injuries and fractures. Also, deformation of the 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 natural childbirth is quite possible. It is also possible to give birth on your own and with 2 degrees of narrowing, but subject to certain conditions, for example, if the fetus is not large. The remaining degrees (3 and 4) are always an indication for caesarean section.

Clinical narrow pelvis- mismatch of the fetal head with the parameters of the pelvis of the woman in labor, diagnosed during childbirth. In this case, the pelvis has normal physiological parameters and shape. It is considered narrow, since the fetus is quite large or incorrectly presented with the forehead or face. For this reason, the child cannot be born naturally.

Normal pelvis sizes

The measurement of the pelvis is carried out with a special instrument, a tazometer, which measures:

The distance between the anterior superior angles of the iliac pelvic bones. Normally, it is 25-26 cm.
The distance between the furthest points of the iliac crests. Normally, it is 28-29 cm.
The distance between the greater trochanters of the femur. Normally, it is 31-32 cm.
The distance from the middle of the upper outer edge of the symphysis to the supracacral fossa. Normally, it is 20-21 cm.
Rhombus of Michaelis (lumbosacral rhombus). Normally, its diagonal value is 10 cm, vertically - 11 cm. If there is asymmetry or its parameters are less than normal values, then this indicates an incorrect structure of the pelvic bones.

Additionally, it is possible to obtain data on the parameters of the pelvic bones using the following studies:

X-ray pelviometry. This study is allowed at the end of the third trimester, when all the tissues and organs of the fetus are already formed. Thanks to the procedure, you can find out the shape of the bones and the sacrum, determine the direct and transverse dimensions of the pelvis, measure the fetal head and determine whether it corresponds to its parameters.
Ultrasound procedure. On ultrasound, it is possible to determine the correspondence between the size of the fetal head and 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- measurement of the circumference of the wrist joint of a woman, thanks to which it is possible to determine the thickness of the bones and determine the direct size of the cavity of the entrance to the small pelvis. Normally, the circumference of the wrist joint is 14 cm. If it is larger, then the bones are massive, if less, then they are thin. For example, with insufficient external dimensions of the pelvic bones and with a normal Soloviev 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 on a special account. It is very important, in this case, to determine the date of birth, since it is extremely undesirable to prolong the pregnancy. A 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 complications in the fetus (respiratory failure, oxygen starvation, birth trauma, circulatory disorders in the brain, clavicle fracture, damage to the bones of the skull and, worst of all, intrauterine death) and the mother (weak labor activity, premature discharge of amniotic fluid, postpartum infection, the threat of uterine rupture).

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At the first visit to the gynecologist for registration for pregnancy, a woman must measure the size of the pelvis. These data are recorded in the medical record of the pregnant woman, but the repeated ones must be measured even in the maternity hospital before the onset of childbirth. The measurement is necessary in order to identify the anatomically narrow pelvis in time and choose the appropriate tactics for conducting childbirth.

Normal sizes

The female pelvis is a cylindrical short canal of bone tissue, in contrast to the male, whose shape resembles a truncated cone. The structure of this area is such that a child can be born without hindrance through the existing channel. Therefore, women have a wide pubic angle, the cape of the sacrum protrudes slightly forward, and the coccyx is not so strongly bent.

The bones are covered with layers of muscle and accumulation of adipose tissue, the amount of which varies greatly from woman to woman. Therefore, despite the external differences in the dimensions of the hips, the normal dimensions of the pelvis fit into a relatively narrow range.

The volume is measured with a special device resembling a curved compass with beads at the ends - a tazometer. The following dimensions and distances are taken into account when measuring:

Distantia spinarum is the space between the superior anterior iliac spines. Normally it is 25-26 cm.
Distantia cristarum - a number that shows the distance between the most distant points of the iliac crests, is 28-29 cm.
Distantia trochanterica is a distance that reflects the distance between the greater trochanters of the femur. This is the point that is the highest on her body. Normally, the distance between the skewers is 30-31 cm.
Conugata externa - external conjugate, means direct size. Measured in the supine position, with the lower leg bent and the upper leg straight. One end of the tazomer is pressed against the upper edge of the symphysis, and the other end against the supracacral fossa. Normally, this distance is 20-21 cm.
Conugata vera is a true conjugate. Its size is determined by counting - 9 cm is subtracted from the length of the outer conjugate. Another way to determine is to subtract 1.5-2 cm from the diagonal conjugate. Norm 11-12 cm.
Conugata diagonalis is the length of the segment between the protruding point of the promontory of the sacrum and the upper edge of the symphysis. It is determined according to the data of a vaginal examination, normally it is 12.5-13 cm.

Properly performed measurement makes it possible to determine the risk group for the development of complications during pregnancy and childbirth.

What is included in the concept of a narrow pelvis?

If the size of the pelvis in any of the indicators differs from the normal one by 2 cm or more, then it is considered anatomically narrow. But the main indicator is the parameter of the true conjugate. It must be over 11 cm.

There is also the concept of a clinically narrow pelvis. This is a functional condition that develops during childbirth due to a mismatch between the size of the fetal head and the parameters of the pelvis. That is, initially the measurement results may fit into the norm. The reasons for the development of the condition are:

large fetal weight is the most common cause;
incorrect insertion of the baby's head;
, as a result of which the head cannot take the configuration necessary for childbirth.

A clinically and anatomically narrow pelvis requires a special approach. Often such pregnancies end in childbirth through. But if the narrowing that is diagnosed during childbirth is an absolute indication for surgery to save the life of the child and mother, then the anatomical features are divided into degrees. Pregnancy management depends on the severity.

This condition is not so common - it is detected in 3% of cases, and clinically only in 1.5-1.7% of all births.

What forms of narrowing are found?

A single classification of narrowing has not been approved, therefore, various approaches are used. In post-Soviet countries, they are based on the form and degree of size change. The shape of the narrowing can be common or rare.

Common ones include:

transversely narrowed;
flat, which includes simple, flat rachitic and with a decrease in the straight diameter of the wide part;
uniformly narrowed.

Rare forms account for only 4.4% of the total number of changes. These include:

oblique and oblique;
change in the pelvis with exostoses, bone tumors, after fractures with displacement;
other forms.

Some forms of the structure of the narrow pelvis in women, adopted by the classification of species in the post-Soviet space

Another approach to the classification of pathology is also used - according to the size of the true conjugate. The frequency of occurrence is also different. If with 1 degree of narrowing, up to 96% of cases are detected, then the second one accounts for less than 4%, and the 3rd and 4th degrees of narrowing practically do not occur. This classification includes the following parameters:

1 degree - 11-9 cm;
2 degree - 9-7.5 cm;
3 degree - 7.5-5 cm;
Grade 4 - less than 5 cm.

But such an approach to setting the degree of narrowing is not always informative. Sometimes there is a decrease in the transverse size, and the true conjugate remains within the normal range. Then the classification by degrees for the transversely narrowed pelvis is applied:

1 degree with a transverse size of the entrance 12.5-11.5 cm;
2 degree, if the diameter is 11.5-10.5 cm;
3 degree when the inlet diameter is narrowed less than 10.5 cm.

Such approaches to classification are not used everywhere. In the West and in the English-language literature, they adhere to the division into forms of the pelvis, which are established depending on the results of an x-ray examination:

Gynecoid - corresponds in structure to a normal female pelvis.
Android - has the features of the location and shape of the bones, as in men - narrowing down, protruding cape of the sacrum.
Platipelloidal - flattened, the pelvis looks flattened in the anteroposterior direction.
Anthropoid - a characteristic shape for primates, narrowing from the sides.

Features of the structure of the female pelvis, according to Western classification

In the pictures, a plane is drawn through the transverse dimension, which divides the entrance into two parts - upper and lower. Depending on the combination of their shapes, 12 additional configurations are formed. They also distinguish between a large, middle and small pelvis, the latter corresponding to a narrow one.

Causes of irregular shape

The pelvic bone forms the girdle of the lower extremities. It is formed as a result of the fusion of several bones: ischial, pubic, iliac. Behind, they are connected to the sacral spine and serve to hold the lower extremities.

The bones of the girdle of the lower extremities develop unevenly. A child is born into the world with bones that have not yet grown together, which are interconnected by cartilage. The most intensive growth occurs in the first 3 years. But they do not grow together in one stage. The first adhesions occur at the age of 5-6 years. By the age of 7-8 years, the ischial and pubic bones should completely grow together. At 14-16, all bones should be almost fused, and at 20-25 there are no traces of cartilage between the bones.

The growth stages of the lower extremity girdle are also extended in time. In girls, the transverse size of the entrance increases very rapidly at 8–10 years of age, then slows down at 10–12 years of age and again grows rapidly at 14–16 years of age. The anteroposterior size increases more gradually.

These data must be taken into account by mothers of girls, teachers and sports coaches. If negative factors act during periods of intensive growth, this will lead to displacement of bones that have not yet fused and the formation of an irregular shape. These impacts include the following:

weight lifting;
uneven load distribution between the right and left side;
incorrect sitting or standing position;
jumping from a great height;
walking in heels.

A certain role of properly selected clothing is also noted. Tight jeans that compress the hips and buttocks will not benefit a teenager.

The period of intrauterine development also affects the formation of bone and cartilage tissue. If the fetus lacked basic substances, there was a violation of mineral metabolism, this can affect the state of the bone apparatus.

The reasons for the changes may lie in the nature of nutrition, living conditions and the level of the social environment, past infections. The transferred poliomyelitis, tuberculosis of bones, osteomyelitis can affect health. Injuries directly to the bones of the girdle of the lower extremities, spine, or legs are dangerous.

Favorable social and living conditions, the level of medical care and the absence of child labor led to the disappearance of rachitic, kyphotic, oblique pelvis and severe degrees of curvature of the shape.

On what grounds can a narrowing be suspected?

An external examination without determining the size of the anatomically narrow pelvis will not allow you to accurately determine the degree of narrowing. Women's hips are very variable in volume, the degree of deposition of adipose tissue does not allow assessing bone parameters. Only the use of a tazometer gives an accurate assessment.

It is possible to assume a change in size by analyzing the anamnesis of life. With injuries of the legs or spine suffered in childhood, diagnosed with rickets, and timely treatment was not carried out, pathology cannot be avoided.

An obstetric history is collected from the following indicators:

time, their character;
How did previous pregnancies and births go?
weight of children at birth;
whether there were breaks and injuries, divergence of the symphysis.

This allows you to evaluate the reproductive function, the possibility of childbirth in a natural way. The condition of the skeleton, joint mobility, weight and height are also necessary to assess the condition of the pregnant woman. External examination at a later date allows you to suspect changes in size. Anatomically narrow pelvis is determined by the angle of its inclination. Normally, it is 45-55 °, and with pathological narrowing, it is much more. In this case, the sacrum is tilted backwards, and the lumbar lordosis is more pronounced.

But size measurements alone are not enough. Not always the parameters of the large pelvis can indicate the state of the birth canal. Therefore, additional indicators are used:

The lateral conjugate is a gap equal to 14.5-15 cm. It is measured between the upper iliac spines on each side.
The height of the symphysis is the length of the dense bony part of the pubis. Normally, it is 5-6 cm. If this distance is less, then the true conjugate will be shorter. So the pelvis is narrow.
The circumference of the pelvis is a conditional parameter, but 85 cm is considered normal.
Solovyov index. Determined by the circumference of the wrist. Normal is 1.4-1.5 cm. An increased value indicates a greater thickness of the bones, which leads to a decrease in the capacity of the birth canal.
The sacral rhombus of Michaelis. It is well visible on the sacrum. Normally, it is of the correct shape with almost equal sides. When the shape of the bones of the girdle of the lower extremities changes, the muscles that form the rhombus move, and its configuration changes. The dimensions of the diagonals of the rhombus are normally 10 and 11 cm in width and height. If we divide it in half by a horizontal line into 2 triangles, then the height of the upper one is 4.5 cm.
Measure the distance between the inner parts of the ischial tuberosities. Normally, this distance is 9.5 cm.

Additional Research

The diagnosis and the degree of narrowing of the anatomically narrow pelvis is made using more than one examination method. The doctor takes into account not only the data of numerous measurements. It is also necessary during the vaginal examination to carefully probe the inner surfaces of the bones. They should be smooth, without irregularities, roughness and curvature (exostoses). An experienced doctor can roughly estimate the capacity of the birth canal.

Complements obstetric research methods, the use of x-rays or. At the very beginning of pregnancy, the use of radiation diagnostics is contraindicated. There is a bookmark and the formation of all organs and systems. Therefore, radiation exposure can lead to serious consequences. But this method is safe if the child is already at the 38th week of gestation: all organs are already formed, short-term exposure cannot cause a violation of their function.

Another option for X-ray examination is the study of the structure of the pelvis at the stage of pregravid preparation. Before planning a conception, you need to assess your body's ability to bear a healthy fetus and reduce the risks of unwanted complications.

X-ray method of research during pregnancy is not often used. Women who, according to the data of external measurements and taking into account additional parameters, did not reveal any deviations, as well as those who did not have a history of complications of childbirth, can do without X-ray diagnostics. It is recommended to take pictures at a later date in the following cases:

there are deviations in the measurements of the small and large pelvis;
according to ultrasound and counting methods, the size of the fetus exceeds 4 kg;
past births were protracted;
during childbirth, a clinically narrow pelvis developed;
there were complications in the form of injuries to the symphysis;
in history - the imposition of obstetric forceps;
fetal trauma in the past;
breech presentation in the current pregnancy.

Ultrasound is a safe examination method. Therefore, it can be used to determine the size of the small pelvis at any gestational age.

Possible complications

Childbirth with an anatomically narrow pelvis can result in the development of complications that threaten the life of the mother and fetus. This condition of the birth canal often leads to an incorrect position of the fetus, which persists until the very birth. This is transverse, oblique or. Even in the normal position, the mobility of the head remains for a long time, which cannot be pressed against the entrance to the small pelvis.

Childbirth with an anatomically narrow pelvis of the 3rd degree of narrowing is carried out using a caesarean section

The outcome of pregnancy depends on the degree of narrowing. If this is 1 degree, then in the absence of other contraindications, natural childbirth is possible. At 2 degrees, childbirth can be delayed. Long duration creates a threat of antenatal fetal death. 3 degree narrowing is an absolute indication for caesarean section.

If it was decided to conduct childbirth through natural routes, then you need to beware of the following complications:

prenatal or early rupture of amniotic fluid;
prolapse of small parts of the body of the fetus;
premature detachment of the placenta;
fetal hypoxia during childbirth or intracranial trauma;
anomalies of labor activity;
the transition of an anatomically narrow to a clinically narrow pelvis;
rupture of the pubic joint;
overstretching of the lower segment and rupture of the body of the uterus;
urogenital and intestinal-vaginal fistulas, which arise from tissue compression by the presenting part of the fetus;
risk in the 3rd stage of labor and early postpartum.

An anatomically narrow pelvis in obstetrics leads to life-threatening complications. The mechanism of their development is associated with a mechanical obstacle in the way of a child being born. Therefore, the water that has poured out ahead of time will not allow the head to be inserted normally and form a contact zone. And a large amount of amniotic fluid can carry away the arms or legs of the child, which will lead to their loss from the birth canal. In this case, the biomechanism of childbirth will be disrupted, they can move towards anomalies of labor activity.

Divergence of the pubic joint

In the postpartum period, the wrong choice of labor management tactics can lead to signs of pubic symphysis divergence. Ruptures of this ligament are extremely rare. The provocateur of what happened is relaxin, which loosens the cartilage tissue, relaxes the ligamentous apparatus. You can suspect a gap or discrepancy if you cannot independently change the position of the body in bed and severe pain in the pubic area. But the exact diagnosis is established on the basis of x-rays.

Treatment in this case involves tight bandaging of the thighs and buttocks, strict bed rest. For some women, the traditional bed is replaced with a hammock, so that under the force of its own weight, the pubic bones come together. If the gap was recognized in the early period, then 2-3 weeks are enough for treatment. With late onset of symptoms, it will take 3-4 weeks to recover.

Fistulas

The mechanism of formation is associated with prolonged pressure on the tissues of the fetal head. This creates a zone of impaired blood supply. The tissues are exposed to hypoxia - oxygen starvation, and mechanical trauma. Therefore, a fistula later forms at the site of pressure.

This pathology is diagnosed not immediately after childbirth, but much later. It is accompanied by discharge from the vagina of feces, gases, pus when connected to the rectum, and urine when connected to the bladder. Treatment in this case is only surgical. This is explained by the fact that an epithelial lining appears in the cavity of the fistula canal, which can no longer grow together. Therefore, it is necessary to excise it, separating the canals of the vagina and the rectum or bladder.

Danger for the child

With a narrow pelvis, the newborn is also at high risk of cranial injury. Especially if the birth is delayed. The structural features of the human skull are such that by the time of birth, people have only bone plates interconnected by cartilage. And in some areas there are no cartilages, there are only dense membranes - fontanelles. After birth, they gradually close - they grow into cartilage tissue, and then they are replaced by bone.

With a narrow pelvis, the newborn is at high risk of cranial injuries.

But if childbirth occurs with a delay of several days or more, then the cartilage tissue has time to grow a little. Therefore, the fetal head will not be able to accept the configuration, it will experience great pressure, which can affect the neurological status of the child and the nature of the maturation of the nervous system.

Therefore, after birth, such children should be observed by a neurologist. In the delivery room, if a cranial injury of a newborn is suspected, the presence of a pediatric resuscitator is required. If necessary, the child is placed under observation in the intensive care unit.

What tactics is chosen by the doctor?

The course of pregnancy with an anatomically narrow pelvis is no different from normal. Difficulties may arise closer to the time of birth. The protocol provides for mandatory holding. In this case, the presenting part of the fetus is determined. Until 35-36 weeks, he occupies the final position. This is the deadline for doing it. But in the presence of other risk factors, this technique is not used.

The birth plan is drawn up for each woman individually. 1 degree of narrowing is not an indication for surgery. But in the presence of aggravating circumstances, the choice remains with the doctor. Risk factors for 1 degree of narrowing are:

large size of the fetus, confirmed by ultrasound;
breech presentation;
a scar on the uterus after a cesarean or other operation;
chronic fetal hypoxia;
advanced age of the woman in labor;
first birth;
stillbirth in history;
anomalies in the development of the genital organs.

If there was a premature outflow of amniotic fluid, then labor induction is carried out. But at the same time, the degree of narrowing should not exceed the first, and there should not be other aggravating factors.

When choosing childbirth through the natural birth canal, a functional assessment of the pelvis is mandatory (determination of the signs of Vasten, Zanheimeister). Be sure to keep a partogram (temporary recording of the stages of cervical dilatation), prevent fetal hypoxia. A woman most of the time is connected to a CTG monitor to assess the condition of the fetus and the degree of contractions (more on the procedure,).

The doctor and midwife must be prepared for the need to perform obstetric forceps or vacuum extraction of the fetus. There must be a connection with children's resuscitation, so that in case of an emergency, the newborn is provided with timely assistance.

To prevent bleeding in the postpartum period, Oxytocin is prescribed drip. This hormone is released naturally and causes the myometrium to contract. During childbirth, it is used carefully so as not to cause violent labor and rapid labor, which are dangerous with a narrow pelvis.

The level of modern medicine has led to a significant reduction in the deformities of the pelvic bones. Therefore, mothers of girls should take care of the reproductive health of their daughters in early childhood. It is not for nothing that children are scheduled visits by an orthopedist-traumatologist, who evaluates the condition of the hip joint and other bones.

Proper nutrition in childhood, vitamin D intake during autumn and winter by children under one year of age reduced the incidence of rickets, especially in the form of severe manifestations that lead to bone deformities. As you grow older, you need to choose the right shoes, monitor the physical and labor load, and during puberty and the manifestations of puberty. Then for a girl planning a pregnancy, the state of her bone apparatus will not become an obstacle to gestation and childbirth.

Assessment of the anatomical structure and size of the pelvis begins with a conversation, during which you can find out health problems before pregnancy. As a rule, a narrow pelvis in women is a consequence of:

genital infantilism;
rickets;
tuberculosis;
injuries and fractures in the pelvic region.

How to determine a narrow pelvis according to external data?

When assessing the musculoskeletal system, special attention is paid to the growth of the expectant mother. Narrowing of the pelvis is most typical for short women (less than 160 cm) with signs of sexual immaturity: male-type hair growth, narrow shoulders and chest, poorly developed mammary glands, etc. Often, a decrease in the size of the pelvic cavity is indicated by a curvature of the spine and limbs, insufficient mobility (ankylosis) of the knee and hip joints.

How to determine a narrow pelvis using a pelvis meter?

Tazomer - a device designed to measure the size of the female pelvis (pelviometry). Outwardly, the tool resembles a compass with rounded ends and a centimeter scale.

To determine the narrow pelvis in a pregnant woman, external dimensions are measured, since the internal parameters of the bone pelvis are not available for evaluation.

To determine whether a woman has a narrow pelvis or not, you need to know the parameters of three transverse and one straight dimensions.

N (abbr.) - norm

Cross dimensions:

Spinarum(segment between the highest points of the right and left iliac bones). N 25-26 cm.
Cristarum(measured between the furthest points of the right and left iliac crests). N 28-29 cm.
Trochanterica(determine the distance from the left to the right large trochanter of the femur). When determining this transverse dimension, the thickness of the subcutaneous fat in the thigh area should be taken into account. N 31-32 cm.

The measurement is carried out in the supine position, with straight legs and arms extended along the body. When assessing the third transverse dimension, the legs must be moved and slightly bent.

IMPORTANT! Starting from the third trimester, with a long position of a woman on her back, the pregnant uterus puts pressure on the vessels, disrupting the venous outflow and provoking the appearance of inferior vena cava compression syndrome. This fact should be taken into account when conducting pelviometry.

Straight size:

External conjugate (k. externa) - a segment between the supracacral fossa and the highest point of the pubic symphysis. N 20-21 cm.

To measure the external conjugate, the pregnant woman is laid on her side as follows: the underlying leg should be bent at the hip and knee joints, the upper leg should be straightened.

How to determine a narrow pelvis, based on the numbers obtained?

A narrowing of the pelvis in a woman is said to be in the event that one or more external dimensions are less than the norm by 1.5 cm or more.

IMPORTANT! Compliance with the external dimensions of the norm does not guarantee the absence of a narrow pelvis in a woman. When evaluating the data, one should take into account the massiveness of the bones and the thickness of the subcutaneous fat. The option when a woman with outwardly wide hips has a narrow pelvis is quite acceptable.

How to determine a narrow pelvis by internal dimensions?

An important indicator in determining the narrow pelvis is the true conjugate. This is the internal size of the entrance to the narrow part of the pelvic ring, which is the gap between the most protruding point of the sacral promontory and the junction of the pubic bones.

The true conjugate plays an important role in the passage of the child through the birth canal, as it is the narrowest point in the pelvic cavity. N - not less than 11 cm.

Bimanual examination evaluates the diagonal conjugate, namely, the distance from the highest point of the cape of the sacrum to the lower edge of the pubic symphysis. During vaginal examination, the tip of the doctor's middle finger rests on the top of the cape, and the edge of the palm rests on the edge of the pubic joint.

As a rule, with a diagonal conjugate equal to 12.5-13 cm, the fetal head moves freely along the birth canal.

To calculate the true conjugate, you need to know the outer or diagonal conjugate.

True conjugate = outer conjugate minus 8-9 cm or diagonal conjugate minus 1.5-2 cm.

IMPORTANT! When determining a narrow pelvis, they also evaluate:

direct exit size: a segment between the lower edge of the pubic bone and the coccyx (N 11 cm);
transverse exit size: after palpation of the ischial tuberosities, the distance between them is measured (N 9.5 cm).

How to determine a narrow pelvis using additional measurements?

Rhombus of Michaelis.

Represents a site in the lumbosacral region in the form of a rhombus. The upper corner of the rhombus is the base of the sacrum, the lateral corners are the posterior superior iliac spines, and the lower corner is the apex of the sacrum.

N of the Michaelis rhombus: longitudinal dimension 11 cm, transverse dimension 10 cm.

The vertical size of the lumbosacral rhombus normally corresponds to the true conjugate.

Solovyov index.

You can determine a narrow pelvis using a centimeter tape by measuring the circumference of the wrist. In N, the Solovyov index is 14-15 cm.

A wrist thickness of more than 15 cm indicates the massiveness of the bones in a woman, which means that the pelvic cavity will be smaller.

The pubic joint.

The womb is the gap between the upper and lower edges of the symphysis. In N, the height of the womb is 4-5 cm.

With a height of the pubic joint of 7 cm or more, childbirth in a natural way is impossible.

How to determine a narrow pelvis by the shape of the angle of the pubic articulation?

In N, the pubic angle is obtuse (from 90 to 110 °), therefore, with any deviation, they speak of an incorrect structure of the female pelvis.

How to determine a narrow pelvis in childbirth?

If the size of the child's head does not match the size of the pelvic cavity, they speak of a clinically (functionally) narrow pelvis. This complication makes it impossible for a child to be born through the birth canal.

It is possible to identify a clinically narrow pelvis on the basis of Vasten: determination of the elevation of the fetal head above the womb.

The insertion of the fetal head into the small pelvis occurs when the cervix is fully dilated. With a narrow pelvis, the advancement of the child is difficult, which means that Vasten's sign will be positive (the fetal head protrudes above the bosom).

IMPORTANT! Most foreign experts came to the conclusion that determining the size of the pelvis does not carry any informative value in determining the tactics of childbirth. Even with the use of additional methods such as computed tomography (CT) and bone radiography, the obtained data on the narrowing of the pelvis are not the basis for a planned caesarean section.