Shortening of the tubular bones of the fetus in the third trimester. Formation of the fetal skeleton. Fetal pathologies - severe combined dysplasias

26.06.2020

A prerequisite for the successful diagnosis of many skeletal defects is that most of the bones of the skeleton during ultrasound examination are detected at the beginning of the second trimester. So, in terms of 12-14 weeks. it seems possible to clearly identify the long tubular bones of the upper and lower extremities, ribs, spine, bones of the cranial vault. The hands and feet are also available for visualization, but the bone elements are very small, which makes it difficult to qualitative anatomical assessment.

In this regard, it is necessary to highlight the main diagnostic criteria indicating a particular pathology of the fetal skeleton. These criteria are usually identified with the correct performance of ultrasound with a mandatory assessment of the anatomical integrity of all limbs, head and internal organs of the fetus.

For the correct diagnosis of bone defects, the following indicators must be taken into account:

the presence and anatomical integrity of the limb;
shortening or increasing the length of the tubular bones;
the severity of the shortening;
deformation of tubular bones;
number of bones;
acoustic density of bones;
condition of soft tissues on the limbs;
the shape and structure of large joints
the shape and structure of the spine;
limb mobility; visual and subjective

Most of the listed criteria are usually detected during standard biometry or visual assessment of the integrity of fetal organs. Most of the bones of the fetal spine can be identified by ultrasound already at the beginning of the second trimester of pregnancy, which creates favorable conditions for establishing their presence and number. To determine the expected growth of the fetus, it is best to use the V.N. Demidov.

It is important to note that the first echographic signs of bone shortening usually appear after 18 to 22 weeks. pregnancy. These signs consist in the lag of the length of the tubular bones from the standard indicators by 2-3 mm, which makes it difficult or even impossible to determine the nosological affiliation of the defect and its prognostic significance.

If these violations are detected, it is usually recommended to repeat the study with an interval of 4-6 weeks.

At full-term pregnancy, the lag of the length of the tubular bones from the standard values by 4-5 mm is manifested by the growth of the newborn 42-46 cm, and in the adult state - 350-160 cm. This category of people among the population of Europe belongs to the group of normal stunted, without pathologies. Therefore, the detection of a slight lag in the size of long tubular bones does not require reflection in the ultrasound protocol in the form of a pathological conclusion.

Lagging of the length of the femur in the last weeks of pregnancy by 5-8 weeks. in absolute terms is 6-12 mm. The growth of newborns with such a pathology ranges from 40-44 cm and in general condition does not exceed 130-140 cm. This category in terms of its growth rates refers to abnormally short stature.

Unfortunately, the number of severe childhood dysplasias, pronounced disorders of the development of the bone apparatus, is constantly growing. A number of television programs are devoted to how difficult it is for people without arms and legs, and for patients suffering from deformities of the limbs. But few people think that they may face such a situation in their family.

Fortunately, with the development of ultrasound, limb anomalies and others are detected in early pregnancy.

Gynecologist's appointment - 1000 rubles. Complex ultrasound of the pelvis - 1000 rubles. Reception based on test results - 500 rubles. (optional)

Why is the development of limbs in the fetus impaired?

There are many reasons for the appearance of children with such deformities:

Hereditary factors... Diseases causing skeletal deformities are hereditary. An example is achondroplasia - dwarfism caused by underdevelopment and shortening of the legs and arms. In popular programs about the Roloff family, a typical case is shown when people with achondroplasia first have a son, and then a grandson with such a deviation.
Genetic failuresarising in the process of fertilization or in the first stages of a baby's development. The reason for the deviations can be infections, even a banal flu, – , , , ... It is especially dangerous if the expectant mother has had an infection at the beginning of pregnancy.
Taking certain medications.The most striking example is the thalidomide catastrophe - birth in Europe in 1959-1962. 12 thousand children with limb underdevelopment. Their mothers were prescribed a sedative drug thalidomide during pregnancy. These drugs include antidepressants, drugs that affect blood clotting, some antibiotics, retinoids used to treat acne. Tragedy happens when the expectant mother takes medications, not knowing that she is pregnant or the doctor will prescribe a drug that is contraindicated for women in the position.
Bad habits and harmful working conditions,affecting heredity, Substances causing deformities are called teratogenic. These include compounds of arsenic, lithium and lead. Leads to congenital anomalies and radiation exposure. Children with abnormal bone development are born to mothers who abuse alcohol and use drugs. Since hazardous substances and radiation infect eggs in a woman's body, problems may arise in women who once worked in hazardous industries.

Patients belonging to these groups require careful throughout pregnancy.

What malformations of the limbs are visible on ultrasound

The bones of the baby are visible in the early stages of pregnancy - the femur and humerus - from 10 weeks, the bones of the legs and forearm - from 10 weeks. At this time, you can already count the fingers, see most of the bones of the skeleton and see how the child moves the arms and legs. Once during this period .

At 16 weeks, just from the moment , the length of the large bones can be measured by assessing the development of the fetus. Consider the size and shape of the limbs. A slight curvature of the legs is not an anomaly, but a pronounced deformation is a sign of pathology.

All other parts of the skeleton - the spine, ribs, cranial bones - must be properly developed and not deformed.

The sizes of the bones of the child's limbs are shown in the table. It should be understood that the indicators are averaged, because each baby develops individually. The size of the limbs is assessed in conjunction with the rest of the indicators. Small children have shorter arms and legs than large ones.

Term, week	Shin	Hip	Forearm	Shoulder
11-12		5,6-7,3
13-14		9,4-12,4
15-16	15,0-18,0	16,3-20,0	12,0-15,0	15,0-18,0
17-18	21,0-24,0	24,0-27,0	18,0-20,0	21.0-24,0
19-20	27,0-30,0	30,0-33,0	23,0-26,0	27,0-30,0
21-22	33,0-35,0	36,0-39,0	20,0-30,0	30,0-35,0
23-24	38,0-40,0	41,0-44,0	30,0-35,0	38,0-40,0
25-26	44,0-46,0	46,0-49,0	37,0-39,0	43,0-45,0
27-28	47,0-49,0	51,0-53,0	41,0-43,0	47,0-49,0
29-30	51,0-53,0	55,0-57,0	43,0-44,0	49,0-51,0
31-32	55,0-56,0	59,0-61,0	48,0-49,0	55,0
33-34	58,0-60,0	63,0-65,0	50,0-52,0	58,0-59,0
35-36	61,0-63,0	67,0-69,0	54,0-55,0	61,0-62,0
37-38	64,0-65,0	71,0-73,0	55,0-56,0	63,0-64,0
39-40	66,0-67,0	74,0-75,0	57,0-58,0	65,0-66,0

First fetal screening - severe pathologies of fetal development are already visible

At the first screening from 11-14 weeks, you can determine most of the severe deformities of the child associated with abnormal development of arms and legs. Often these vices are combined with others. .

Fetal pathology	Manifestations	Consequences
Amelia	Complete absence of limbs	Children are born without arms and legs, often with internal defects
Ecromelia	Underdevelopment of arms and legs, sometimes accompanied by the absence of hands and feet.	Despite the development of prosthetics, most of these children have a disability.
Congenital amputation	One or two limbs are missing	For unknown reasons, an undeveloped handle may not be accompanied by other pathologies, but the absence of a leg, as a rule, is combined with other malformations.
Adactyly	Lack of fingers	The anomaly is often accompanied by underdevelopment or absence of the tongue (aglossia-adactyly), defects in the hard palate and lips. Possibly abnormal development of the eyelids and jaws
Hemimelia	Shortening or missing of the bones of the forearm and lower leg	The defect is combined with clubfoot and other malformations of the limbs
Phocomelia	Formed feet and hands begin immediately from the body, and the arms and legs are greatly shortened and dysfunctional	Even with modern prosthetics, it is far from always possible to restore the functions of a child's limbs.
Clubhand	Abnormal development of the forearm bones	Often combined with defects of the heart, spine, It is one of the signs of severe hereditary pathology - Fanconi anemia, manifested by impaired blood clotting, abnormal development of the skeleton and mental retardation
Lobster claws	On the arms or legs, two or four toes are formed, separated by a cleavage of the palm or foot.	The defect is often accompanied by anomalies in the development of the face - "cleft palate", "cleft lip", defects in the development of the eyes and jaws
Radial aplasia	Underdevelopment of the forearm bone	It is often a symptom of hereditary TAR, Aase-Smith, Holt-Oram syndromes, in which heart defects, spinal defects, hematopoietic disorders and mental retardation are diagnosed Most of these children die at an early age

Fetal pathologies - severe combined dysplasias

With hereditary pathologies, found from 15 weeks, defects in the development of the bones of the skeleton are combined with other defects. Most babies die in utero, immediately after birth and during the first years of life. In this case, it happens or is found ... With some diseases, children with disabilities can live a long time.

Disease	Symptoms	Forecast
Thanatophoric dysplasia	Significant shortening of the limbs, narrow chest, large head with a prominent forehead. The hips are curved in the shape of a telephone receiver. Sometimes the thighs are straight and the skull is clover-shaped.	Bad. Babies are born dead or die after birth
Osteogenesis imperfect	Multiple limb deformities. Propensity to fracture after birth	Children die at an early age or are disabled. There is a lag in physical development
Ellis-van Creveld syndrome	Shortening of limbs, abnormal development of hands, dwarfism, fragility of bones.	More than 50% of children die. Survivors have serious health problems caused by underdevelopment of the genitourinary and cardiovascular systems
Achondrogenesis	Multiple skeletal anomalies - short limbs, underdeveloped spine, ribs, lower jaw,	Babies are born dead or die after birth
Achondroplasia	The fruit has a large head with prominent frontal tubercles and short limbs. The most common form of dwarfism	It does not affect life expectancy. Such people may even have offspring, but in 50% of cases, their children will inherit the anomaly.
Yarkho-Levin syndrome	Anomalies in the development of vertebrae and ribs, compressed short chest, "crab-like" chest, head "depressed" into the shoulders, disproportionately short body	Children often die from lung problems. Survivors have a disability
Dystrophic dysplasia	The child is lagging behind in development, having a small height and weight. Long bones are shortened, arms and joints are deformed	Most of the patients are disabled. since due to underdevelopment of bones, they cannot move independently

If the child has skeletal anomalies

In case of detection of obvious severe anomalies, the doctor will suggest ... Otherwise, a woman will have to face the birth of a child with an incurable hereditary disease.

amniocentesis - analysis of amniotic fluid;
chorionic biopsy - sampling of chorionic membrane cells;
placentocentesis - collection of placental tissues;
cordocentesis - a study of blood from the umbilical cord.

Detection of genetic abnormalities in a fetus predicts the birth of a child with a severe disability, sometimes incompatible with life. Of course, every woman decides for herself whether to leave such a child for her. But it should be borne in mind that most children with genetic diseases affecting not only the skeletal system, but also internal organs, despite treatment, die at an early age.

The decision must be fully balanced. It is no secret that mothers who decide to give birth to a baby with serious pathologies often do not realize the full severity of the situation. In this case, it is better to trust the opinion of doctors.

Where is an expert ultrasound scan done to detect fetal defects in St. Petersburg

You can undergo such an examination during pregnancy at the Diana clinic in St. Petersburg. The price of an ultrasound scan of the fetus depends on the duration of pregnancy and starts at 1300 rubles. Reception of a gynecologist based on ultrasound results - 500 rubles. The cost of a medical abortion is 3500 rubles.

Fetus is an unborn baby in the mother's womb. In medicine, it is generally accepted that the embryo develops for the first two months, and then, before birth, the fetus.

The fetal skeleton begins to form literally from the first days of conception. Already on the second day, the fertilized egg, which is actively dividing and growing rapidly, forms special cells - ectoderm. In the future, bone tissue and bones of the skeleton develop from the ectoderm.

Human skeleton- an extremely important component of our body. Bones support the body, determine its shape and size, and protect internal organs from injury. Bone tissue is involved in mineral metabolism in the body, the skull protects the human brain, the bone marrow affects the immune system, the main processes of hematopoiesis take place in it.

Overview of fetal skeletal development

Bones are 70% composed of extra strong bone tissue containing a large amount of mineral salts. Basically, these are: calcium, magnesium and phosphorus. Of course, in addition to them, other elements are needed for the correct formation of the bones of the skeleton - aluminum, copper, selenium, fluorine, zinc, but in much smaller quantities. The fetus takes all these substances from the mother's body, so it is important that a pregnant woman eat full and varied food containing "building material" for the child.

If necessary, the doctor can additionally prescribe vitamins and minerals. Do not neglect these recommendations: if the fetus does not receive the necessary substances for the formation of bones, the skeleton may form with impairments.

Limb shortening includes shortening of the entire limb (micromelia), the proximal part (rhizomelia), the middle part (mesomelia) and the distal part (acromelia). To diagnose rhizomelia and acromelia, it is necessary to assess the correspondence of the size of the humerus and femur to the size of the bones of the forearms and legs.

With some skeletal dysplasias the structure of the hands and feet is disturbed. The term "polydactyly" describes conditions in which there are more than five fingers on a limb. Distinguish between postaxial polydactyly, when the extra finger is localized on the side of the ulna or fibula, and preaxial polydactyly, when it is located on the side of the radius or tibia. Syndactyly is the fusion of soft tissues or bone tissue of adjacent fingers, and clinodactyly is the curvature of one or more fingers. The most common spinal anomaly found in skeletal dysplasias is platysondilia, which is a flattening of the vertebral bodies.

The literature contains descriptions of cases diagnostics in the antenatal period of kyphosis and scoliosis of the spine, as well as hemivertebrae and frontal clefts of the vertebral bodies.

Fetal skeleton biometrics

Measurement length of tubular bones the fetus is widely used in obstetric practice to determine the duration of pregnancy. In nomograms used for this purpose, the length of the tubular bones is an independent variable, and the duration of pregnancy is dependent. However, this also represents an important difference, in nomograms used to assess the correspondence of the length of bones to normal values for the corresponding period, the gestational age is already used as an independent variable, and the length of bones is used as a dependent one.

So to get it right enjoy with nomograms of this type, the investigator must know exactly the true gestational age of the fetus. In this regard, pregnant women from the risk group for the development of skeletal dysplasia in the fetus should be advised to begin observation in prenatal diagnostic centers from early pregnancy, in order to be able to use all clinical methods for determining the gestational age of the fetus. For patients with unspecified gestational age, ratios between limb length and fetal head circumference may be used.

Some researchers for this purpose, the biparietal size is taken as an independent variable, however, the measurement of the head circumference has an advantage, since this indicator does not depend on its shape. The weak side of this approach is that it is based on the assumption that the bones of the fetal skull are not involved in the pathological process, which cannot but be the case with some forms of skeletal dysplasia.

Nomograms and the figures in our articles represent the mean of the limb lengths and their 5- and 95-percentile confidence intervals. It should be remembered that when using these upper and lower limits, 5% of potentially healthy fetuses in pregnant women from the general population are outside of them when assessed on these nomograms. It is most preferable to use the 1st and 99th percentiles of the lengths of the limb bones for the corresponding gestational age as the confidence limits, which would meet the more stringent criteria.

Unfortunately, it has not yet been completed. works, the number of patients examined in which would provide a significant difference between the indicators for the 5th and 1st percentiles. However, most of the skeletal dysplasias that can be diagnosed in the prenatal or neonatal periods are characterized by a pronounced shortening of the size of the tubular bones, and given this circumstance, the difference between the use of boundaries at the 5th percentile compared to the 1st is not so decisive.

The exception is the heterozygous form achondroplasias, in which the length of the limbs is only moderately reduced until the third trimester of pregnancy. In this case, abnormal development can be detected by a change in the slope of the growth curve of the femur. In the study by L Goncalves and P. Teanty, on the basis of 127 observations of 17 types of different dysplasias, a discriminant analysis was carried out, which showed that the length of the femur is the best biometric parameter that can be used to make a differential diagnosis among the five most common diseases: tatophoric dysplasia , osteogenesis imperfecta of type II, achondrogenesis, achondroplasia and hypochondroplasia. S. Gabrieli et al. assessed the possibility of early diagnosis of skeletal dysplasia in high-risk patients.

In their research included 149 women with an uncomplicated course of singleton pregnancy in the period from 9 to 13 weeks, counting from the last menstruation, which were examined using a transvaginal scan. The polynomial regression method was used to assess the relationship between femur length and gestational age, as well as between biparietal and parietal-coccygeal sizes. Eight patients with a history of the birth of children with skeletal dysplasia were examined with an interval of 2 weeks until 10-11 weeks of gestation. A strong correlation was found between femur length, parietal-coccygeal and biparietal dimensions.

The first trimester was diagnosed only two out of five cases of skeletal dysplasia (both were recurrent cases of osteogenesis imperfecta and achondrogenesis). This study suggested that the assessment of the correlation of femur length with parietal-coccygeal size and femur length with biparietal size in the first trimester may be useful in the early diagnosis of severe forms of skeletal dysplasia. In cases of milder forms of this pathology, biometrics are of limited value.