Venous duct. Intrauterine development of the umbilical-portal venous system: two- and three-dimensional ultrasound examination

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Introduction

Assessment of the umbilical portal venous system (UPVS) has become an important part of antenatal fetal assessment. UPVC abnormalities associated with chromosomal and structural abnormalities, Doppler assessment of ductus venosus flow has become a screening tool for Down syndrome in the first trimester of pregnancy. In addition, recent studies have shown the need to assess blood flow in the fetal liver with intrauterine retention growth.

In the fetus, venous blood flow in the liver is unique, as it is provided by two embryonic and functionally different systems: the umbilical and portal/vitelline systems. From 5 to 10 weeks of pregnancy, a network of anastomoses is formed in the liver between the umbilical and vitelline systems, and the volume of placental blood flow increases, which then flows to the heart through this hepatic system. The intra- and extraportal venous system develops from the right vitelline vein. In the umbilical system, the right umbilical vein regresses, and the portal system directly develops from the left umbilical vein. The ductus venosus, which emerges from the umbilical-portal system, supplies oxygenated blood directly to the fetal heart.

Methods

A prospective study of anatomically normal fetuses was conducted as part of routine antenatal care in a low-risk population. In most cases, studies were performed during fetal sonography at 14–16 weeks and 19–24 weeks or in the third trimester of pregnancy, as part of an assessment of fetal growth.

We excluded fetuses with any abnormal sonographic findings, including the presence of “soft markers” for aneuploidy, in which a normal karyotype was not established. ​​Pregnancies complicated by maternal diseases that could affect fetal development were also excluded. Cases with pathological volume were also excluded. amniotic fluid, associated or not associated with abnormal intrauterine growth of the fetus.

Ultrasound examinations were performed on or equipped with transabdominal 4-8 MHz or transvaginal 5-9 MHz transducers with a 70 Hz high-pass filter.

Only if sonograms with optimal visualization were obtained were the UPVCs included in the study. All examinations were taken in a standard cross-section of the upper abdomen (the section commonly used to measure abdominal circumference). In the section we visualize the stomach and the L-shaped portal sinus (this is the confluence of vessels that originate from the end of the umbilical vein; it was also defined by Mavrides et al. as the vascular space extending from the origin of the inferior branch of the left portal vein to the right portal vein (Fig. 1)). From this perspective, we performed studies by imaging the stomach at a point distal to the transducer to determine the junction of the portal sinus and the main portal vein, which runs on the left side between the stomach and the descending aorta. The connection between the portal vein and the portal sinus was first identified using two-dimensional (2D) ultrasound. After this, color Doppler with high definition flow (HDFlow) was used to achieve the best imaging mode and also to check the direction of blood flow (Fig. 2 a and b). The 3D technique was applied only in cases where the portal sinus and portal vein could not be detected in the same plane in other imaging modes. For 3D HDFlow we used a sample volume angle of 30-35° (Fig. 3). In order to evaluate the intrahepatic branches of the portal system, we adopted the Couinaud liver segmentation system. A longitudinal section was also used to determine the normal course of the umbilical vein and ductus venosus.

Fig.1. Ultrasound images of a normal intrahepatic umbilical vein that connects to the left and right portal veins. On a section measuring the abdominal circumference of a fetus at 23 weeks of gestation. (a) Transverse section used to measure fetal abdominal circumference. (b) Cross-sectional sonogram in the sagittal plane indicated by the dotted line.

Fig.2. On the sonogram we observe the junction of the main portal vein and the bifurcation of the right and left portal branches from the portal sinus in a fetus at 23 weeks of gestation, presented without (a) and with (b, c) HDFlow high-definition flow. Images (a) and (b) show a cross-section of the fetal abdomen. The arrow points to the hepatic artery. Image (c) corresponds to a sagittal section of the main portal vein indicated by the dotted line.

Fig.3. Image of the fetal portal vein at 24 weeks' gestation: normal intrahepatic vascular anatomy is shown in cross section (a). 3D HDFlow allowed visualization of the main portal vein and its branches simultaneously, whereas this was not possible in 2D (b-d).

results

During the study, we studied 208 fruits. The mean gestational age at the time of examination was 25.1 weeks. In the longitudinal section, we noticed that the course of the umbilical vein in an upward direction enters the liver, where it connects with the portal system. At the left intrasegmental groove of the liver, it joins the left portal vein, which then courses sharply to the right, creating an L-shaped segment known as the portal segment. The main portal vein bends around the main sulcus on the left. The junction of the main portal vein with the portal sinus is the anatomical point of separation between the right and left branches, and is located downward (Fig. 2 c) and to the right along the base of the ductus venosus. The right portal vein branches into two main branches: the anterior and posterior branches at some distance from the junction of the main portal vein and the portal sinus. Three branches emerge from the left portal vein: two on the left (inferior and superior branches) and one on the right (medial branch) (Fig. 3). During the study period, in only one case (0.4%) were we unable to detect an L-shaped segment of the left portal vein, indicating the absence of a horizontal portion of the left portal vein. In this case, the ductus venosus arises from the right portal vein rather than from the portal sinus (Fig. 4).

Fig.4. A case of development of the umbilical-portal system in a fetus at 23 weeks of gestation (a b). The typical L-shape of the left portal vein cannot be identified (a) and the ductus venosus has a different course (b, arrow) compared to the usual development (c, arrow).

At the confluence of the main portal vein and the portal sinus (Figure 2), we noticed that their confluence angle varied continuously from perpendicular to almost completely parallel to the direction of the lines. Accordingly, three main types of communication between the main portal system and the portal sinus have been classified. The most common type was observed in 140 (67.3%) fetuses. It is a T-shaped connection, with an end-to-side anastomosis between the main portal vein and the portal sinus (Fig. 5). This type of connection showed a wide range of connection angles and varying distances from the branching site of the posterior branch of the right portal vein. The connection ranged from a vertical T-shaped insertion into the portal sinus, far from the bifurcation of the right branch of the right portal vein (Fig. 5 a), to a more acute angle of connection and a shorter distance from this bifurcation (Fig. 5 b and 5 c), forming a cruciform structure consisting of four vessels: the main portal vein, the left portal vein and two branches (anterior and posterior right portal vein) (Fig. 5 d). In 26 fetuses (12.5%), an X-shaped connection was observed between the main portal vein and the portal sinus (Fig. 6), characterized by the formation of a side-to-side anastomosis, which runs almost parallel. In some cases, there is a gap between the main portal vein and the left portal vein, which is an intermediate shape between the second and third type of connection (classified as an H-shape) and is observed in 30 (14.4%) fetuses. In this type, the connections between the main portal vein and the posterior right portal vein were separated from the right portal vein by small vessels (Fig. 7). We also observed different distances between vessels. In the most extreme case, the connection between vessels could not be visualized together in the same plane in greyscale mode. Only in 3D using the HDFlow technique was it possible to demonstrate the thin vessel that connected them (Fig. 7c). In our series, classification of the type of connection between the main portal vein and the portal sinus was not possible in 12 (5.6%) cases, which was mainly explained by the intermediate morphology. Eight of them were between types T and X, and four were between types X and H.

Rice. 5. Variants of anastomosis of the main portal vein and portal sinus end to side in a fetus at 24 weeks of gestation. (a) T-shaped anastomosis. (b) different distances from the branching site of the posterior branch of the right portal vein were noted; in some cases, the left portal vein and the right portal vein branched directly from the main portal vein in a trident-shaped pattern (c). (d) The more acute angle of the connection is an intermediate form between the end-to-side and side-to-side types of anastomoses.

Fig.6. Variants of anastomosis of the main portal vein and portal sinus “side to side” in a fetus at 24 weeks of gestation: X-shaped anastomosis. Sonograms (a) and (b) show the connection with different distances between the main portal vein/posterior branch of the right portal vein complex and the left portal vein/anterior branch of the right portal vein complex. An almost complete gap between each other is shown, which represents an intermediate shape between the X and H shapes. (c) Three-dimensional visualization with high quality 3D HDFlow image flow reconstruction.

Rice. 7. A case of H-shaped anastomosis of the main portal vein and portal sinus in a fetus at 24 weeks of gestation. The main portal vein and the posterior branch of the right portal vein are separated from the left portal vein and the anterior branch of the right portal vein by small vessels connecting them to each other (a and b). (c) The image represents a case in which the main portal vein/anterior branch of the right portal vein and the main portal vein/posterior branch of the right portal vein complexes were so distant from each other that they could only be visualized using the 3D HDFlow.

Conclusion

In this study, we examined the connection between the main portal vein and the portal sinus. The umbilical-portal venous system is a complex of vessels that supply the liver as well as the fetal heart.

We decided to adopt the anatomical nomenclature proposed by Mavrides et al, using the term “portal sinus” for the L-shaped umbilical portion of the left portal vein. The main reason for this was our ability, using 2D and 3D HDF, to easily visualize the inferior branch of the left portal vein as a landmark for the origin of the portal sinus. In addition, this technique allowed us to visualize the main portal vein and its branches simultaneously, which was not possible in 2D (Fig. 3 b–d).

An important feature of our study is the fact that we were able to accurately describe the different anatomical connections between the main portal vein and the portal sinus in a large number of fetuses during pregnancy. Knowledge of these anatomical variations is important in the diagnosis of portal venous system anomalies, such as complete and partial agenesis of the portal vein.

The blood circulation of a fetus is significantly different from that of an adult.

The fetus is in the womb, which means it does not breathe with its lungs - the ICC does not function in the fetus, only the BCC works.

The fetus has communications, they are also called fetal jesters, these include:

1. foramen ovale (which drains blood from the RA into the LA)
2. arterial (Batalov) duct (duct connecting the aorta and pulmonary trunk)
3. ductus venosus (this duct connects the umbilical vein to the inferior vena cava)

These communications close over time after birth, and when they are not closed, congenital malformations are formed.

Now we will analyze in detail how blood circulation occurs in a child.

The baby and mother are separated from each other by the placenta; the umbilical cord, which contains the umbilical vein and umbilical artery, goes from it to the baby.

Oxygen-enriched blood travels through the umbilical vein as part of the umbilical cord to the fetal liver; in the fetal liver, the umbilical vein is connected to the inferior vena cava through the DUCT VENOUS. We remember that the inferior vena cava flows into the RA, in which there is an OVAL WINDOW, and through this window blood flows from the RA into the LA, where the blood mixes with a small amount of venous blood from the lungs. Then from the LA through the left interventricular septum into the LV, and then enters the ascending aorta, then through the vessels to the upper part of the body. Collecting in the SVC, the blood of the upper half of the body enters the RA, then into the RV, then into the pulmonary trunk. Let us remember that the ATRERIAL DUCT connects the aorta and the pulmonary trunk, which means that the blood that entered the pulmonary table, for the most part, due to the high resistance in the vessels of the ICC, will not go into the lungs as in an adult, but through the ductus arteriosus into the descending part of the aortic arch. About 10% is thrown into the lungs.

The umbilical arteries carry blood from the fetal tissues to the placenta.

After ligation of the umbilical cord, the ICC begins to function as a result of the expansion of the lungs, which occurs with the child’s first breath.

Closing communications:

• First, the ductus venosus closes by the 4th week, and in its place the round ligament of the liver is formed.
• The ductus arteriosus then closes as a result of vasospasm due to hypoxia for 8 weeks.
• The oval window is the last to close, during the first half of life.

During the prenatal period the blood flowing from the fetal abdomen through parallel blood vessels is mixed with blood from the umbilical vein and transported into the ductus venosus, from where it immediately follows into the vena cava, draining below the heart but above the liver, thus bypassing the liver. Immediately after birth, blood flow through the umbilical vein stops, but most of the blood flowing through the portal vessels still follows the ductus venosus, and only a small amount of blood passes through the sinuses of the liver.

However 1-3 hours after birth the muscular wall of the ductus venosus contracts strongly, and blood flow through this area stops. As a result, the pressure in the portal vein begins to increase from values ​​close to zero to 6-10 mm Hg. Art., which is sufficient to ensure the movement of blood from the portal vein through the sinuses of the liver. Although the ductus venosus rarely remains patent, almost nothing is known about the reasons for its closure.

Newborn nutrition. Before birth, the newborn receives almost all the energy it needs through the metabolism of glucose, which it takes from the mother's blood. After birth, the amount of glucose stored by the newborn in the form of muscle glycogen is sufficient to meet the energy needs of his body for only a few hours.

Liver the newborn is not yet functionally perfect at the time of birth, which prevents sufficient expression of the processes of gluconeogenesis, therefore the concentration of glucose in the blood of the newborn quickly decreases on the first day of life to a very low level (approximately 30-40 mg/dl of plasma), which is less than half the glucose concentration in normal. Fortunately, there is a mechanism that allows the newborn to use stored fats and proteins to meet metabolic needs until mother's milk is provided 2-3 days later.

Occurs quite often Problems, associated with obtaining a sufficient amount of fluid for newborns due to the fact that in newborns the rate of fluid turnover is 7 times higher than in adults, and mother’s milk appears only after a few days. Typically, the body weight of newborns decreases by 5-10%, and sometimes even by 20% in the first 2-3 days of extrauterine life. Most of the lost mass comes from water, and a smaller part from dense substances.

Important feature of the neonatal period is the instability of humoral and reflex regulatory systems. This is partly due to the immaturity of some organs, and partly due to the fact that the regulatory systems themselves did not have time to adapt to the new conditions of existence.

Normal breathing rate the newborn is approaching 40 per minute, and the tidal volume of each breath is approximately 16 ml. This tidal volume makes the breathing volume close to 640 ml/min, which in relation to body weight is approximately 2 times higher than this figure in adults. The functional residual capacity of the lungs of newborns is only half the functional residual capacity of adults per unit body weight.

This difference explains very large fluctuations in gas composition blood of newborns depending on the phase of breathing against the background of a decrease in respiratory rate, because It is the functional residual capacity that smoothes out changes in the gas composition of the blood.

(ductus venosus, PNA, JNA)
see Ductus venosus.

View value Duct venosus in other dictionaries

Venous- venous, venous (anat.). Adj. to vein. Deoxygenated blood.
Ushakov's Explanatory Dictionary

Duct— see leak and pierce.
Dahl's Explanatory Dictionary

Venous Adj.— 1. Correlative in meaning. with noun: vein, connected with it. 2. Characteristic of a vein, characteristic of it.
Explanatory Dictionary by Efremova

Duct M.— 1. A river branch, a stream connecting two bodies of water. 2. Narrow connecting cavity, canal (in the body).
Explanatory Dictionary by Efremova

Venous— see Vienna.
Kuznetsov's Explanatory Dictionary

Duct- -A; m.
1. River branch; stream, river connecting two bodies of water. The lakes are connected by a deep channel. In the lower reaches the river splits into many channels.
2. Anat. Narrow........
Kuznetsov's Explanatory Dictionary

Allanoid Duct— (dutus allantoicus, LNE) a canal lined with epithelium connecting the cavity of the hindgut with the cavity of the allantois; in the human embryo the AP is reduced.
Large medical dictionary

Anastomosis Venous- (a. venosa) A., connecting two venous vessels.
Large medical dictionary

Arantsiev Channel- (G. S. Aranzi, 1530-1589, Italian anatomist and surgeon) see List of anatomists. terms.
Large medical dictionary

Ductus arteriosus- (ductus arteriosus, PNA; ductus arteriosus (Botalli), BNA; synonym Botalli proto) blood vessel connecting the pulmonary trunk of the fetus with the aorta; formed from the left sixth (aortic) branchial........
Large medical dictionary

Bartolin's Channel— (S. Bartholin, 1655-1738, Danish anatomist) see Large sublingual duct.
Large medical dictionary

Botall's Channel- (ductus arteriosus (Botalli), BNA; L. Botallo, 1530-1600, Italian surgeon and anatomist) see Ductus arteriosus.
Large medical dictionary

Warton's Channel- (ductus Whartonianus; Th. Wharton, 1614-1673, English anatomist) see Submandibular duct.
Large medical dictionary

Venous Return- blood circulation indicator: volumetric blood flow velocity in the right atrium; Normally, it strictly corresponds to the cardiac output.
Large medical dictionary

Venous Return Cardiotomy- sharply increased venous return, observed after some heart surgeries (pericardiectomy, mitral commissurotomy, etc.).
Large medical dictionary

Venous Return Coronary- coronary circulation indicator: volumetric blood flow velocity in the coronary sinus; normally equal to 50-80% of the volumetric blood flow velocity in the coronary arteries.
Large medical dictionary

Venous Stagnation— (stasis venosa) see Venous hyperemia.
Large medical dictionary

Ductus Venosus— (ductus venosus, PNA, JNA) see List of anat. terms.
Large medical dictionary

Venous Sinus of the Sclera— (sinus venosus sclerae, PNA, BNA, JNA; synonym: venous sinus of the sclera, Laut canal, scleral canal, Schlemm’s canal) a circular venous vessel located in the thickness of the sclera on the border with........
Large medical dictionary

Venous Angle- (angulus venosus; synonym Pirogov venous angle) the confluence of the subclavian and internal jugular veins, forming the brachiocephalic vein.
Large medical dictionary

Virzungow Channel- (ductus Wirsungianus; J. G. Wirsung, 1600-1643, German anatomist) see Pancreatic duct.
Large medical dictionary

Wolffian Channel- (ductus Wolffi; S. F. Wolff, 1733-1794, morphologist) see Duct of the primary kidney.
Large medical dictionary

Hensen's duct- (V. Hensen) see Connecting duct.
Large medical dictionary

Hepatopancreatic Duct- (ductus hepatopancreaticus, LNE; hepato- + Greek. pankteas, pankreatos pancreas) section of the embryonic common bile duct from the place where the duct of the ventral anlage enters it.......
Large medical dictionary

Thoracic Duct- (ductus thoracicus, PNA, BNA, JNA) lymphatic vessel through which lymph flows into the venous bed from the legs, pelvis, walls and organs of the abdominal cavity, left arm, left half of the chest,........
Large medical dictionary

Vitelline Duct- see Vitelline duct.
Large medical dictionary

Vitelline Duct- (ductus vitellinus, LNE; synonym: vitelline-intestinal duct, umbilical-intestinal duct) a canal in the vitelline stalk, lined with endodermal epithelium, connecting the cavity of the middle........
Large medical dictionary

Bile duct- (ductus choledochus) - Common bile duct.
Large medical dictionary

Bile Duct Common— (ductus choledochus, PNA, BNA, JNA; synonym bile duct) extrahepatic gland, formed by the connection of the hepatic and cystic ducts; opens on the major duodenal papilla.
Large medical dictionary

Female Duct— see Paramesonephric duct.
Large medical dictionary

Every pregnancy is not only the joy of expecting a baby, but also worries about its development and health. Even the most carefree expectant mother thinks about this one day. And this anxiety even drives some women into a frenzy. A hundred years ago, a pregnant woman had no idea what her child would be like until she gave birth. But today science allows us to “spy” in advance how the baby is developing. To do this, the woman is sent once a trimester for routine screening. Decoding the results of screening in the 1st trimester is an exciting process, because it is now that most developmental pathologies are detected. But don't worry in advance. The screening itself is absolutely safe, and its results will most likely please and reassure you.

1st trimester screening - what is it?

Prenatal screening is a set of measures and procedures carried out to assess the course of pregnancy and the condition of the fetus.

On the one hand, if, according to the results of the examination, everything is fine with the baby, the woman has no reason to worry. On the other hand, if pathologies are identified, she receives the right to make an informed choice that determines her future life. Therefore, there is no reason to be afraid of screening. After all, if there is something wrong with the fetus, it is advisable to find out about it as early as possible in order to make a decision about the advisability of continuing the pregnancy. At the same time, a woman should know that no one can force her to terminate her pregnancy, just as no one has the right to prohibit her from doing so.

In the first trimester, screening consists of two parts - a biochemical analysis of maternal blood and an ultrasound examination of the fetus and uterus.

Ultrasound screening of the first trimester is a procedure that should precede the rest.

It is carried out to determine the following parameters:

• fetometry (sizes of individual indicative anatomical structures) of the fetus;
• condition of the uterus and its appendages;
• heart muscle contraction frequency;
• sizes of the heart, bladder, stomach;
• condition of blood vessels.

The purpose of the examination is to determine the compliance of fetal parameters with accepted standards. If individual indicators differ from them, this is a reason to suspect developmental pathologies in the baby.

The second component of first trimester screening is taking blood from the vein of the expectant mother.

It is carried out to determine the level of two indicators:

• beta component of the hCG hormone;
• PAPP - A or, as it is also called, protein A.

These values ​​must also be within strict limits, and their deviation from the norm usually indicates a disturbance in the development of the fetus or other unfavorable factors that threaten pregnancy.

These include pregnant women:

• over 35 years of age;
• who are closely related to the father of the child;
• undergoing any course of treatment;
• having a history of pregnancy failure;
• who gave birth to children with pathologies or have such persons in their family.

But the triggering mechanisms of some pathologies are still unknown. Therefore, anomalies can also occur in a fetus whose mother does not fall into any risk group.

Of course, no one can force a woman to undergo screening, but refusing screening is an irresponsible decision.

Timing of the first screening

Like the next two screenings, examinations at the beginning of pregnancy should be carried out within a strictly designated period. Blood sampling and ultrasound are most informative from the tenth week to the end of the thirteenth. If you undergo the procedures in the 12th week, then all organs will be visualized.

At the beginning of pregnancy, changes in the embryo’s body occur very quickly, so every day brings new information. In this regard, it is better to complete the first screening in one day. It is permissible to visit the ultrasound room the previous day in order to donate blood to the laboratory the next morning.

What pathologies can first trimester screening detect?

Although the practice of sending every pregnant woman for screening has existed for many years, doctors rarely explain why this is needed and how it “works.” Therefore, women usually go for examination automatically, not understanding its importance. The main task of the first screening is to identify some of the most common pathologies in the fetus, if they are present.

Signs of Down syndrome on ultrasound

Down syndrome is a chromosomal pathology that is found in every 700th fetus. Thanks to screenings, the number of babies born with this disease has almost halved in recent years.

The disease directly depends on the age of the mother, therefore all women over 35 years old automatically fall into the risk group. The pathology develops at the moment of fertilization and, according to geneticists, does not depend on the lifestyle and habits of the pregnant woman. Down syndrome occurs when an extra chromosome is formed and is called trisomy 21. As a result of this chromosomal disorder, the child develops severe defects of the heart, digestive organs and other systems. Children with this pathology are mentally retarded and have a characteristic appearance.

At the first screening, several facts can indicate a chromosomal disorder.

1. Expanded collar space. At later stages, the child’s lymphatic system is formed and this parameter ceases to be informative.
2. Nasal bone not visible. This is true for 60-70% of children with Down syndrome. At the same time, in 2% of healthy babies at the indicated dates, the nasal bone is also not visible.
3. Smoothed facial features.
4. The blood flow differs from normal in 8 cases out of 10. But for 5% of children without any pathologies this is the norm.
5. An enlarged bladder can also indicate trisomy.
6. Reduced, relative to normal, maxillary bone.
7. One, instead of two, umbilical artery. This anomaly is characteristic of many chromosomal pathologies.
8. Tachycardia also indicates various developmental defects, including Down syndrome.

Children with this disease may well survive until birth and then exist for quite a long time. But this does not alleviate their plight as severely disabled people who are constantly in need of help and control.

Patau syndrome

Another chromosomal abnormality that develops in one in 10 thousand babies. The disease is caused by the extra 13th chromosome. A genetic failure can occur at any time during gestation and affect the entire body or only individual organs. Sometimes the pathology is mild.

On ultrasound, a doctor may suspect Patau syndrome based on the following signs:

• tachycardia;
• asymmetrical development of the brain hemispheres or its underdevelopment;
• slow formation of the skeleton and, as a consequence, discrepancy between bone lengths and accepted standards;
• a hernia caused by late formation of the abdominal muscles.

Children born with the syndrome described rarely live more than a few months and almost never more than a year. The most obvious signs of pathology will be discernible closer to the second screening.

Edwards syndrome

This is a chromosomal malfunction caused by the presence of the third chromosome in the set, the 18th chromosome. The pathology is also congenital and today there is no reliable data about what provokes it and how to prevent it. The cause of an extra chromosome is an abnormal gamete.

In a sick fetus, ultrasound records:

• high heart rate;
• absence of the nasal bone at this time;
• one umbilical artery instead of two;
• umbilical hernia.

Children with Edwards syndrome are born with low birth weight, although the gestation period is normal. Babies have many developmental defects (heart, gastrointestinal tract, lungs), which rarely allow them to live beyond the age of one year.

Smith-Opitz syndrome

This pathology is characterized by metabolic disorders and is caused by a mutation of a certain gene. Children born with this problem may have facial anomalies, mental retardation, and six-fingered children. At the first ultrasound, the pathology has almost no characteristic signs, except for an increase in the collar space. For more later oligohydramnios and specific skeletal deformities may occur. The disease is diagnosed mainly through amnio- or cordocentesis.

A gene mutation can manifest itself weakly, then it is classified as the first type and the baby has every chance of living, but lagging behind mentally and physically from his peers. With type 2 syndrome, newborns most often die.

De Lange syndrome

Another genetic failure, the causes and triggering mechanism of which have not yet been sufficiently studied. It manifests itself as multiple pathologies of the skeletal structure, facial anomalies and dysfunction of internal organs. A characteristic feature is a thin upper lip, thin, fused eyebrows and thick, long eyelashes. It occurs rarely, in only one case out of 30 thousand.

It is almost impossible to diagnose pathology in the embryonic period. Its presence may be indicated by the absence of protein A in the mother's blood. But it is unacceptable to make a diagnosis based only on this sign, since in 5% of cases a false positive result occurs. Closer to the second screening, the fetus may experience a discrepancy in bone size with the norm.

As you can see, at the specified period, ultrasound can only reliably diagnose the presence of pathology, but it is difficult to accurately name its type. More reliable results may provide chorionic villus sampling or a second screening.

What do they find out at the first screening?

The data obtained in the laboratory are intended, after all, for the doctor, and not for the inquisitive mind of the experiencing expectant mother. Remember that no one is specifically interested in intimidating you or hiding the real state of things. Therefore, rely on the experience of the doctor managing the pregnancy and give him the privilege of reading the screening protocol.

HCG norm

This hormone is called the main one during pregnancy. It grows from conception and reaches maximum concentration by 11-12 weeks. Then it drops a little and remains at the same level until delivery.

If hCG is elevated, this may indicate:

• diabetes mellitus in the mother;
• multiple births;
• Down syndrome in the fetus;
• toxicosis.

Reduced hCG is detected when:

• threat of pregnancy failure;
• tubal pregnancy;
• Edwards syndrome.

The parameters may differ in different laboratories, so you should focus not on the quantitative indicator, but on the MoM coefficient, which we will discuss below.

Norm PAPP-A

This is the name of the protein that the placenta produces. Its concentration is constantly growing. If this indicator is higher than normal with other normal data, then there is no reason to worry. You should be concerned if the protein concentration is low.

This may be a sign:

• chromosomal or genetic pathologies;
• risk of miscarriage.

Heart rate (HR)

The fetal heart beats faster than that of an adult, but tachycardia may be one of the signs of developmental pathology. If the fetal heartbeat cannot be heard on an ultrasound, then this definitely indicates a frozen pregnancy.

Thickness of the collar zone (TVZ)

This is the most indicative parameter for the specified period, the deviation of which from the norm almost always indicates pathologies. It is also called the thickness of the collar space. This is the distance from the skin to the soft tissues covering the neck of the embryo. Normally, this figure, depending on the gestational age, is 0.7-2.7 mm. It is measured during the period when the length of the fetus from head to tailbone ranges from 45 to 85 mm. At later stages, TVZ (TVP) becomes uninformative.

Coccygeal-parietal fetal size (CTF)

This parameter is relevant in the 10-12th week. It is measured from the crown to the tailbone and allows you to determine the gestational age as accurately as possible. Already from the end of the 12th week, the baby begins to raise his head and other parameters become indicative.

Nose bone length

The nose is a quadrangular bone, the shortening of which clearly indicates pathological processes in the development of the fetus. Sometimes this bone is absent altogether, which signals complex anomalies that are quite rare. Underdevelopment of the nasal bone (hypoplasia) may be a consequence of the described syndromes and other disorders.

Fetal head size (FHS)

In the early stages, the baby's head makes up most of his body, and the brain develops rapidly. Therefore, head size is the most important indicator characterizing the condition of the fetus. Of particular importance is the biparietal size, measured from temple to temple. If this parameter is higher than normal, then the remaining indicators are evaluated first. It happens that the fetus is simply large and then all fetometric data exceed the norm. But large BPR values ​​may also indicate a cerebral hernia, tumors or hydrocephalus.

All norms of the described data by week are shown in the table below.

Table 1. 1st trimester screening, norms

Please note that a deviation of some parameters by just a millimeter already indicates pathologies, but no one excludes a banal inaccuracy of measurements. Therefore, take a responsible approach to choosing the place where you will undergo the examination.

MoM coefficient

If everything is clear with the units of measurement of fetal parameters, then the results of blood biochemistry require a separate explanation. Each laboratory uses its own software and therefore the results may vary. To unify the obtained data, it is customary to reduce them to a special coefficient called MoM. Indicators from 0.5 MoM to 2.5 do not cause concern. But the closer they are to one, the better. In the research protocol, the laboratory will most likely indicate the amount of hormones and then the MoM coefficient.

Getting ready for research

Due to the fact that the fetus is still very small, you will have to prepare a little for the first ultrasound. The examination can be carried out with a vaginal probe or along the anterior abdominal wall. Everything will depend on the position of the embryo.

1. In the first case, no preparation is required. The doctor will insert a special device, protected by a condom, into the vagina and perform careful manipulations. The procedure does not cause any discomfort, but minor bleeding may be observed for two days after it.
2. Performing an ultrasound through the abdominal wall is absolutely safe and painless. But in order for the doctor to be able to examine the embryo, the bladder must first be filled. To do this, drink at least half a liter of liquid an hour and a half before the procedure. This is a mandatory condition, without which the doctor simply will not see anything.

The slight pressure of the sensor on a full bladder is not very pleasant, but any woman can cope with these sensations. There is a restroom next to each ultrasound room so you can finally relax once the procedure is complete.

Before an ultrasound, it is also undesirable to drink carbonated drinks and eat foods that provoke flatulence.

Biochemical screening of the 1st trimester is mandatory on an empty stomach.

1. The day before blood sampling, refrain from eating any foods that can cause allergies. Even if you have never had atypical reactions to food.
2. Be sure to eliminate nicotine and alcohol, and for the entire period of pregnancy, and not just before tests.
3. Do not eat fatty or fried foods during the day before screening. It is better to exclude smoked meats and products with a long shelf life.
4. If you take any medications on an ongoing basis, be sure to indicate this on the application form. If you are undergoing any treatment, delay screening until after treatment if possible.

The expectant mother receives the results of the ultrasound immediately, but she has to wait a week or a week and a half for a response from the laboratory for biochemical analysis.

Decoding the results obtained

Having received ultrasound and biochemistry data, the woman is sent to her gynecologist, who analyzes the information received. If the results are satisfactory and the woman does not fall into a risk group, no additional tests are required. There is no point in further examinations in the case of a frozen or regressing pregnancy. When the screening data is unsatisfactory, the woman is recommended to consult a geneticist.

Deciphering research data yourself is a risky endeavor. But if you're itching to understand the numbers you're looking at, note that labs usually report results as fractions. The closer its value is to 1, the more serious the situation. That is, the indicator 1:10 is significantly worse than 1:100, and 1:100 is worse than 1:300. This ratio shows how many healthy children in your conditions there are for one with the specified pathology. For example, if in the laboratory’s response you found the entry “trisomy 21 - 1:1500,” this means that the risk of giving birth to a baby with Down syndrome is 1 in 1500. This is a very small probability and you can relax. The ratio is considered to be 1:380.

Remember that even a high risk is not a reason to panic, much less to urgently terminate a pregnancy. You still have invasive diagnostic methods.

And only they can give a clear answer whether your baby specifically has a pathology, and not in theory a group of people with similar parameters.

Safety for mother and fetus

In itself, prenatal screening of the 1st trimester does not pose any danger to either the mother or the fetus. Ultrasound does not affect the fetus, although it is not known for certain whether the examination causes discomfort to the baby. Some experts are of the opinion that during the procedure the child hears a loud noise, which may be unpleasant for him, but is definitely not dangerous.

Blood for biochemistry is taken from the expectant mother from a vein, which is also completely harmless, although not very pleasant. Some women are very afraid of this procedure and even lose consciousness during the process. If you fall into this category, tell your nurse to have ammonia ready.

If the results obtained are satisfactory, then they usually stop there until the next screening. When the data raises concerns, you will need to resort to additional diagnostic methods. At the beginning of pregnancy, this is a chorionic villus biopsy or amniocentesis. The first method allows you to determine with 100% accuracy whether the fetus has congenital pathologies, but too often leads to pregnancy failure. Amniocentesis is less dangerous, but this procedure also leads to spontaneous abortion in one case out of 200.

What to do if there are unfavorable results?

It is absolutely clear that a doctor should interpret the screening results. Without sufficient knowledge, the expectant mother will only create fear in herself, not understanding the numbers obtained. For example, a 40-year-old woman who became pregnant through IVF is very likely to have borderline findings for Down syndrome. This does not mean at all that there is something wrong with her pregnancy specifically. The risk of pathology in a group of women of this age is simply high.

Therefore, if you receive results that cause concern, discuss with your doctor. And maybe not with just one. If finances allow, get tested in another laboratory. Doctors often recommend not to panic ahead of time and to wait for the results of the second screening, which can be done starting from the 15th week.

On what ultrasound can a doctor determine the sex of a child?

Ultrasound is not only a diagnostic method, but also an opportunity to find out the gender of your baby in advance. Theoretically, this becomes possible from the 12th week, when the labia in girls and the penis in boys are visualized. A more realistic period when gender can be determined unmistakably is fifteen weeks. The only problem is to ensure that the fetus turns in the right direction towards the sensor. Alas, this does not happen at the mother’s request and does not depend on the doctor’s manipulations. Sometimes, despite any tricks, the baby does not reveal his main secret until the very birth.

Screening is not a cause for concern, but simply a diagnostic tool. Today, thanks to the Internet, expectant mothers have access to all the knowledge in the world. Unfortunately, the information available is often misleading and scary. But now, when you are already responsible for two lives, the main thing is not to worry. Therefore, do not expect unpleasant surprises from pregnancy and follow your doctor’s instructions.

Video on the topic

In the second trimester, if necessary, a second pregnancy screening is prescribed, which should confirm or refute the data obtained during the first comprehensive examination. Changes in results are carefully studied, compared with standard indicators, and appropriate conclusions are drawn.

Based on them, parents receive information about the intrauterine state of the child. If it is positive, all that remains is to wait for his safe birth. If negative, appropriate measures must be taken - treatment or artificially induced premature birth. In any case, the second screening is a responsible procedure for which you need to be prepared mentally and physically.

Goals

Those who have already undergone the first comprehensive examination know and understand perfectly well why they do the second screening during pregnancy. The purposes of this procedure:

• identify those defects that could not be determined after the first screening;
• confirm or refute diagnoses previously made in the first trimester;
• establish the level of risk of pathologies;
• detect physiological deviations in the formation of the child’s body systems.

• high hCG;
• low EZ and AFP.

• all blood counts are low.

Neural tube defect:

• normal hCG.
• high E3 and AFP.

A bad second screening does not always guarantee a 100% accurate diagnosis. There were cases when completely healthy children were born after it. Even medicine makes mistakes. But you shouldn’t count on the fact that this is exactly your case. In this matter, it is better to rely on the opinion and recommendations of the gynecologist observing the pregnancy. It is he, as a professional, who can take into account the possibility of a false result, which is determined by many different factors.

False results

Although rare, this does happen: second trimester screening produces false results. This is possible if the course of pregnancy is characterized by the following features:

• multiple pregnancy;
• incorrect deadline;
• excess weight overestimates the indicators, underweight underestimates them;

Before conducting the second screening, the gynecologist must identify these factors using a questionnaire and a preliminary examination and take them into account when drawing the results. It is on this that further actions to maintain or terminate the pregnancy will depend.

Further actions

Since the second screening during pregnancy is carried out already in the middle of pregnancy, abortion if severe genetic abnormalities are detected is impossible. What actions can a doctor recommend in this case?

1. Consult a gynecologist about the data obtained if the risk of developing abnormalities is 1:250 or 1:360.
2. Carrying out invasive diagnostic techniques with a risk of pathologies of 1:100.
3. If a diagnosis is confirmed that cannot be corrected therapeutically, fetal extraction is recommended.
4. If the pathology is reversible, treatment is prescribed.

The second screening quite often ends in forced labor, and the couple must be mentally prepared for this. Since a lot depends on these procedures, young parents need to know as much information as possible about them, which will help to understand unclear issues and dispel doubts.

And other features

Before the second screening procedures, the couple always has many questions about how to properly prepare for them and how exactly they go. The doctor does not always have time to carry out detailed educational work on this matter, so you often have to look for the answers yourself. A special block will help make this task easier.

At what time is the second screening done?

From the 16th to the 20th week.

Is it necessary to donate blood at the second screening?

If the ultrasound showed abnormalities, then it is necessary. If there are no suspicions of genetic disorders, the doctor may not prescribe a blood biochemistry test.

What is included in the second screening during pregnancy?

Ultrasound and biochemical blood test taken from a vein.

What does the second screening reveal?

Genetic disorders in the development of the fetus and placenta.

Is it necessary to do a second screening?

At the first bad screening - a must.

How should hCG change at the second screening?

Compared to the results of the first screening, its indicators temporarily decrease.

Is it possible to eat before the second screening?

You cannot eat 4 hours before the second screening, as this may distort the research results.

In some cases, doubts about whether the fetus has developmental abnormalities can be dispelled or confirmed only by a second screening. If the results of the first showed too high a risk of gene mutations, but the pregnancy was not terminated, a comprehensive study must be completed. This allows you not only to soberly assess the situation, but also to make an informed decision about whether to give birth to a sick baby or not. This is a difficult question, but one cannot ignore it: not only the life of the child depends on it, but also the fate of the parents themselves.

This type of examination is prescribed to women who are diagnosed at 11-13 weeks of pregnancy. The initial stage of the first screening during pregnancy is ultrasonography. After this, the pregnant woman is sent for a biochemical blood test.

Such activities make it possible to identify genetic defects and pathologies in the structure of the embryo and respond to them in a timely manner.

How to properly prepare for the first screening?

The procedure under consideration includes two types of examination, each of which requires certain preparation.

Ultrasound

Can be done in two ways:

1. External (abdominal). It is given when the bladder is full, so 30-60 minutes before the start of the procedure, the pregnant woman must drink at least half a liter of purified water without gas or not urinate 3-4 hours before the start of the ultrasound.
2. Vaginal. This type of examination does not require special preparation. Some clinics require patients to bring their own diaper, sterile gloves, and condom for the ultrasound probe to their appointment. All this can be purchased at almost any pharmacy.

(double test)

Provides for the following preparatory activities, which, if ignored, can significantly affect the test results:

• 2-3 days before the test, a pregnant woman should refrain from fatty, salty foods (meat, seafood), citrus fruits and chocolate. The same goes for multivitamins.
• Blood must be donated on an empty stomach. The last meal should be at least 4 hours before the test.
• Doctors also advise avoiding sexual intercourse a couple of days before the screening.

How does the first screening in pregnant women go and what does it show?

This type of examination must begin with. After all, it is ultrasound diagnostics that makes it possible to determine the exact duration of pregnancy - and this very important for the second stage of screening: the double test. After all, the blood norm indicators, for example, for weeks 11 and 13 will be different.

In addition, if an ultrasound examination reveals fetal freezing or the presence of serious anomalies, there will be no need for a biochemical blood test.

Thus, at the time of passing the second stage of the first screening, the pregnant woman must have a conclusion from an ultrasound specialist.

Ultrasonography

This type of examination is conducive to identifying the following physical defects of the fetus:

• Developmental delay.
• The presence of serious pathologies.

Also thanks to ultrasound the gestational age, the number of fetuses in the uterus are determined, the approximate date of birth is established.

In the first third of pregnancy, the following indicators are checked using an ultrasound machine:

1. Distance from the coccyx to the parietal part of the head. This parameter is also called the coccygeal-parietal size (CTR). At the 11th week of pregnancy, CTE varies between 42-50 mm, at the 12th week - 51-59 mm, at the 13th - 62-73 mm.
2. Dimensions of the nasal bone. At week 11 it is not visualized. At 12-13 weeks its parameters are more than 3 mm.
3. Distance between the tubercles of the parietal region, or biparietal size (BPR). Normally, this figure should be 17 mm at the 11th week; 20 mm at 12 weeks; 26 mm at 13 weeks of pregnancy.
4. Fetal head circumference.
5. Distance from forehead to back of head.
6. Brain structure, the symmetry and size of its hemispheres, the quality of the closedness of the skull.
7. Heart rate (HR). Using this parameter, cardiac arrhythmia can be detected. When measuring heart rate, the ultrasound technician must be very careful: due to the short stages of pregnancy, it is possible to confuse the pulsation of the patient’s blood vessels with the heartbeat of the embryo. Normally, the considered indicator varies between: 153-177 in the 11th week of pregnancy; 150-174 – at the 12th week; 147-171 – on the 13th.
8. Parameters of the heart and its arteries.
9. The structure of the femur, humerus, and shin bones.
10. The distance between the inner and outer surface of the skin of the neck, or nuchal translucency thickness (TNT). Normally, this indicator will be: at the 11th week of pregnancy 1.6-2.4 mm; at the 12th week – 1.6-2.5 mm; at the 13th week – 1.7-2.7 mm.
11. The structure of the chorion (placenta), its location. When chorion detachment is detected, its volume is determined and whether there is a tendency to progression. This phenomenon can provoke bleeding and complaints from the pregnant woman about pain.
12. Shape and size of the yolk sac, quality of umbilical cord vascular supply. The yolk sac normally decreases in size by the 12th week of pregnancy, and at the time of testing it should be a tiny (4-6 mm) round cystic neoplasm.
13. The structure of the uterus and its appendages. Particular attention is paid to the ovaries: in later stages of pregnancy, examining them is problematic.

At the time of the first ultrasound screening the fruit must be positioned correctly so that the specialist can carry out a quality inspection and take the necessary measurements.

If the child is positioned incorrectly, the patient is asked to turn over from her back to her side, cough, or squat.

Double test (norms and decoding)

For this type of examination, blood is used from a vein, which is taken on an empty stomach.

Biochemical screening is needed to determine the following parameters:

1.Pregnancy Protein (PAAP) -A )

This protein is produced by the placenta and increases during pregnancy.

Normally, the indicators of this protein will be as follows:

• Week 11-12: 0.77-4.76 mIU/ml.
• Week 12-13: 1.04-6.01 mIU/ml.
• Week 13-14: 1.48-8.54 mIU/ml.

A reduced amount of PAAP-A may be a consequence of the following abnormalities:

1. There is a threat of miscarriage.
2. The developing embryo has Down syndrome, Edwards syndrome, or another genetic disorder.

An increase in the level of RAAP-R in the blood of the expectant mother often does not have an important diagnostic value.

2. Amounts of human chorionic gonadotropin (hCG)

This hormone is produced in the first weeks of pregnancy, reaching its maximum level in the 12th week of pregnancy, after which the amount of the hormone in question decreases.

By studying the amount of hCG in the blood of a pregnant woman, it is possible to determine the presence/absence of chromosomal abnormalities.

In the conclusion sheet, this parameter is written in the “free β-hCG” column.

In the first trimester of pregnancy, the norm of this hormone is as follows:

• Week 11: 17.3-130.2 ng/ml.
• Week 12: 13.3-128.4 ng/ml.
• Week 13: 14.3-114.7 ng/ml.

Elevated hCG levels may indicate several phenomena:

• The developing fetus has Down syndrome.
• The expectant mother has diabetes.
• The pregnant woman suffers from severe toxicosis.

A decrease in the level of the hormone in question may occur against the background of the following factors:

• There is a risk of miscarriage.
• Pregnancy formed outside the uterine cavity
• Failure of the placenta to perform its basic functions.
• The embryo has Edwards syndrome.

What pathologies can be detected during first trimester screening?

In the first three months of pregnancy, examinations can detect or suspect the presence of the following ailments:

• Errors in the structure of the neural tube (meningocele).
• Down syndrome. Prevalence of this disease: 1:700. Timely detection of this pathology made it possible to reduce the birth rate of sick babies (1 in 1100 cases).
• Umbilical cord hernia (omphalocele). An ultrasound examination shows that the internal organs are in the hernial sac and not in the abdominal cavity.
• Edwards syndrome (1:7000). It is characterized by a decreased heart rate, omphalocele, insufficient number of blood vessels on the umbilical cord, and the absence (inability to visualize) of the nasal bone. Pregnant women over 35 years of age are at risk.
• Triploidy. With this pathology, the fertilized egg contains 69 chromosomes instead of 46. This phenomenon can occur due to the irregular structure of the egg, or when two sperm penetrate one egg. Often, with such anomalies, women do not carry the fetus to term or give birth to stillborn children. In those rare cases when it was possible to give birth to a living baby, its life span is limited to a few days/weeks.
• Patau disease (1:10000). Ultrasound reveals retardation in the structure of the brain, tubular bones, increased heart rate, and omphalocele. Often, babies that are born with a similar diagnosis live for a maximum of a couple of months.
• Smith-Lemli-Opitz syndrome (1:30000). It is the result of genetic disorders that make it impossible to properly absorb cholesterol. The pathology in question can provoke many developmental defects, the most serious of which are errors in the functioning of the brain and internal organs.

To confirm some of the above pathologies, it is required additional diagnostic measures, and in most cases they are invasive.

What can affect the results, and can the doctor make a mistake during the first screening?

Screening in the first trimester of pregnancy has certain disadvantages.

On the other hand, an examination still needs to be carried out: timely detection of a particular pathology will make it possible to terminate the pregnancy (if the fetus has serious abnormalities), or take measures to preserve the pregnancy (if there is a threat).

In any case, it will be useful for any expectant mother to know that false positive results screening may occur in the following situations:

1. ECO. With artificial insemination, the parameters of the occipital part of the embryo will be 10-15% higher than normal. A double test will show an increased amount of hCG and a low level (up to 20%) of RAAP-A.
2. Weight of the expectant mother: severe thinness is a consequence of a decrease in the amount of hormones, and with obesity the exact opposite phenomenon is observed.
3. Diabetes mellitus, other diseases related to the functioning of the thyroid system. With such ailments, it is problematic to calculate the risks of diseases in the fetus. Doctors often cancel screening for this reason.
4. Multiple pregnancy. Due to the impossibility to this day of accurately determining the hormonal background of a pregnant woman who is carrying more than one child, her screening is limited to ultrasound examination and does not include biochemical analysis.

Most expectant mothers feel, to one degree or another, fears about the baby in the womb. As a rule, they have no basis. But in some cases, these fears are so strong that it is better for the expectant mother to undergo screening in the first trimester and then wait for the baby calmly. Sometimes this study is recommended by doctors to enable the pregnant woman to decide whether to prolong the pregnancy or whether the risks are too high.

All pregnant women can undergo screening in the first trimester with the consent of both future parents of the baby. In cases where this is a doctor’s recommendation, and the risk of having a sick baby is increased, this examination should be done.

Among the reasons that should encourage a pregnant woman to undergo the first screening during pregnancy are:

• Close family relationship between the pregnant woman and the baby’s father;
• The presence of close relatives of both parents with congenital pathologies;
• A pregnant woman has a baby with congenital pathologies;
• Age of the expectant mother (over 35 years old).

Reasons for first trimester screening will also include those related to the woman’s previous pregnancies:

• Presence of fetal freezing;
• Stillbirth;
• The presence of 2 or more miscarriages;

Risk factors will also include those cases that are associated with:

• With the use of medications prohibited during pregnancy (even when it was vital);
• With viral or bacterial diseases suffered by the mother during pregnancy.

The referral for the first screening will be written by the gynecologist who is observing the pregnant woman. But the place of examination must be chosen by the pregnant woman herself.

It should be noted here that this examination is carried out in 2 stages. The first is an ultrasound, and the second is a biochemical blood test to determine the amount of hCG and PAPP-A hormones. It will be better if the woman undergoes both tests on the same day, and for this it is good to choose a perinatal center where they are both done.

How is the research conducted?

An ultrasound should be done first, and then blood should be taken from a vein for hCG and PAPP-A.

Ultrasound screening of the 1st trimester is carried out in two ways:

• Transvaginally
• Abdominal

The doctor will choose only one of the methods. In a transvaginal exam, a very thin probe is inserted into the vagina. To do this, a woman lies down on a couch without clothes below the waist, bends her knees and spreads them slightly. A sensor placed in a condom is inserted into the vagina. There are no unpleasant sensations observed. But sometimes on the second day there may be slight bleeding.

In an abdominal screening, the examination is performed through the abdomen and requires a full bladder. And you should prepare for this. In this case, the sensor is located on the skin of the abdomen. Here you just need to lie down on the couch and free your stomach from clothes. When screening for the second time (in the second trimester), abdominal filling of the bladder is not required.

The ultrasound results will be given to you and you will need to undergo biochemical screening with them.

Biochemical screening, what is it?

The second screening is taking blood from a vein. When conducting it, in addition to the ultrasound results, the pregnant woman will be asked a number of questions that are extremely necessary for screening.

Then 10 ml of blood will be taken from the vein. The results of this examination are usually ready no earlier than in a few weeks (hCG and PAPP-A). Then they will issue a conclusion.

Dates

First trimester screening is very time-limited. The accuracy of the result will depend on the correctness of their determination. Therefore, it is important to conduct an examination no earlier than the 1st day of the 11th week and no later than the 6th day of the 13th week of pregnancy. If this examination is necessary, the timing is calculated taking into account the medical history, as well as the last menstruation. Usually, when referring for screening, the gynecologist performs pregnancy calculations again and determines the day of the examination.

Preparation

Such a complex and responsible procedure requires some preparation. To be well prepared for screening, you should consider a number of features of the procedure. Since two examinations are performed at once: an ultrasound examination and blood sampling from a vein, they differ slightly in preparation. The general preparation will be the day before the examination (two or three days before that is possible). This preparation for screening is needed

for more accurate results of biochemical blood tests (hCG and PAPP-A). Here's what you should stick to on your diet:

• Eliminate allergenic foods from the diet;
• Do not eat fatty and fried foods;
• Do not eat seafood and smoked meats;
• Don't eat chocolate.

Failure to follow the diet will lead to an increased risk of failure. Directly on the day of the procedure, you should fast 4 hours before donating blood for a biochemical analysis, if the ultrasound will be performed abdominally, you should start drinking still water 30 minutes to 1 hour before, or you can, if possible, not urinate 2-3 hours before the examination . When examining transvaginally, no preparation is needed. As previously noted, you first need to undergo (usually before 11 o’clock in the afternoon) an ultrasound examination, and then donate blood.

Decoding the results

Decoding the results most often takes a long time (up to 2–3 weeks). It is carried out using a special program prisca. The interpretation includes not only ultrasound and biochemical screening, but also monitoring the condition of the pregnant woman, as well as family history. One of the points will be the question: is it necessary to undergo a re-examination at a later date?

The screening results will also answer a large number of questions. Among which will be:

• How high is the risk of congenital pathologies in the fetus?
• Which of the possible genetic diseases are possible and what is their likelihood?
• Should pregnancy be prolonged?

During an ultrasound examination, five main criteria are determined; they can say a lot about possible pathologies and the degree of likelihood of their occurrence.

Thus, the first screening will show the parameters of the coccygeal-parietal size (CPS) of the fetus, which are an indicator of the overall development of the fetus and are characterized very individually for each week.

For the possible development of some chromosomal diseases, it is important to study the thickness of the nuchal zone (TVZ); if it deviates from the norm, there is a suspicion of Down Syndrome and some other complex chromosomal pathologies.

In this regard, the nasal bone is also very important. Which, in a fetus with this disease (60–70%), is formed much later or is absent. It is not detected on ultrasound in approximately 2% of healthy children. Much later it is determined in such pathologies as Pattau syndrome. The norm is when it is visible already at 11 weeks.

One of the important conditions for the absence of pathologies will be heart rate. Its violation may indicate several pathologies: Down syndrome, Edwards syndrome, Pattau syndrome.

During this period, the presence of an umbilical hernia (omphalocele) is already determined when internal organs The peritoneum is located in a thin sac of skin outside the abdominal cavity.

They also look for the presence of reverse venous blood flow, which indicates trisomy (the presence of three chromosomes instead of two, which usually indicates the occurrence of severe genetic diseases).

And the presence of one umbilical cord artery instead of two, which is often a sign of Edwards Syndrome or indicates an omphalocele.

The table below shows data that represents the norm for the fetus at this stage of development. By comparing the ultrasound screening data of the first trimester of a pregnant woman with them, one can judge the development of the fetus.

Indicators of screening studies in the first trimester of pregnancy (normal)

What hormone levels are determined by the first screening?

When conducting a biochemical screening (blood test), the level of two types of hormones, hCG and PAPP-A, is determined:
HCG (human chorionic gonadotropin) is a hormone called the pregnancy hormone; its amount in a woman’s body increases when pregnancy occurs (a pregnancy test is based on this factor). It is bad if its level is increased or decreased. With elevated levels, the risk of developing Down syndrome increases; with lower levels, the risk of Edwards syndrome or placental pathology. The table below shows the normal indicators.

The second hormone being studied is called PAPP-A (plasma protein-A). This is the protein that the placenta produces, and, therefore, with increasing pregnancy, its concentration in the blood increases. By the amount of PAPP-A produced, one can judge some chromosomal pathologies of the fetus. Among them will be:

• Edwards syndrome;
• Down syndrome;
• Cornelli de Lange syndrome
• Rubinstein-Taybi syndrome
• Mental retardation with hypertrichosis.

The fact is that at these times, screening ultrasound examination is not always accurate enough, so the results of biochemical screening are very important. If the result is increased or decreased compared to the norm, then this is already an alarm bell.

The table below shows the results of screening, in which the norm for this hormone is observed.

MoM coefficient

When the results are presented, an indicator such as the MOM coefficient will be present.

The fact is that there is a norm for a given area and age of the pregnant woman, which is converted into a median using the special prisca program. The ratio of the pregnant woman’s indicators to this norm will be the MoM indicator. It is normal when the indicator ranges from 0.5 to 2.5, and ideally when it is close to 1. The entry on the results form should look something like this “hCG 1.2 MoM” or “PAPP-A 2.0 MoM” if this indicator is increased - this is always bad.

Research risks

In addition to the MoM indicators, the results form will also contain a risk assessment: which can be “High” or “Low”, normally “Low”. Usually this is a number with a fraction, for example, 1:370, the larger the fraction, the better. It is desirable that the number be greater than 380. This means that at the birth of 380 babies, one child may have Down syndrome. Here, the higher the number (more than 380), the better. Such risks are defined as “Low”.

Important. When concluding with a “high risk” entry, a ratio ranging from 1:250 to 1:380, as well as MoM indicators for one of the hormones ranging below or above the corridor of 0.5-2.5 units. Screening is considered poor.

The picture shows an example of filling out the form; the screening of the 1st trimester is given, the decoding of this result is described as “Low result”, i.e. good. So we see the entry “Expected risks of trisomy” with the numbers: 21, 18, 13 - these are severe genetic diseases: Down's disease, Edwards syndrome, mental retardation with hypertrichosis, but the individual numbers are very large. Which makes the risks of having a sick baby very low.

What could affect the results?

First of all, it should be taken into account that with twins, screening results are not reliable, here the indicators can be very different, they are usually not interpreted by geneticists. This is especially true for biochemical screening for hormones (hCG and PAPP-A), the result of which is usually significantly increased.

There are also a number of factors that influence the results:

• First of all, this is IVF. Here the PAPP-A indicators will be changed (lower by 10–15%);
• In addition, a condition such as obesity in a pregnant woman will also increase the level of all hormones (hCG and PAPP-A too);
• If a pregnant woman’s weight is very low, then the level of hormones will be below normal;
• Reduces hormonal levels and diabetes;
• It is not recommended to carry out screening in the first trimester after amniocentesis (this is a collection of amniotic fluid for analysis). Blood donation is not recommended here.
• It can also affect the results ordinary fear pregnant woman before the procedure. So far, fear cannot be diagnosed, and its effect on the pregnant woman’s body has not been studied. There is no way to predict the results.

What to do in case of bad tests

If the results form contains the phrase “High Risk”, then this means that the results are poor.

In this case, most likely, the pregnant woman will be asked to visit a geneticist. During the consultation, several options (depending on the screening results) for the further development of pregnancy will be considered:

• The first thing a doctor can recommend is to undergo screening in the second trimester, and then, possibly, in the third trimester.
• In more complex cases, invasive diagnostics will be recommended (sometimes the recommendations are very urgent). Options may include chorionic villus sampling, amniocentesis, or cordocentesis.
• And based on the results of these invasive diagnostics (or one of them), the issue of prolonging the pregnancy will be considered.

Instead of conclusions

The first trimester screening procedure is a complex and troublesome matter. But in many cases it is necessary to determine possible deviations in fetal development in the early stages. Sometimes this will be a signal for closer monitoring of the pregnancy, and in some cases a signal to action, which will help to give birth to a healthy baby.

Unfortunately, medicine is not omnipotent and in some cases it is possible to predict the birth of a baby with chromosomal abnormalities, but it cannot be cured, then only the pregnant woman and the father of the child will decide the fate of this pregnancy.

Sometimes screening in the first trimester is important for purely psychological reasons - it allows a pregnant woman to overcome the fears that overcome her. And this will be the key to the health of the baby and mother, and will help to obtain the desired peace of mind and self-confidence.

What does 1st trimester screening show? This is an ultrasound examination that helps determine the possible presence of chromosomal diseases in the early stages of pregnancy. During this period, women should also undergo a blood test for PAPP-A. If it turns out that the 1st trimester screening results are poor (ultrasound and blood counts), then this indicates a high risk of Down syndrome in the fetus.

1st trimester screening standards and their interpretation

During an ultrasound, the thickness of the fetal neck fold is examined, which should increase proportionally as it grows. The examination is carried out at 11-12 weeks of pregnancy, and the cervical fold should be from 1 to 2 mm at this stage. By week 13 it should reach a size of 2-2.8 mm.

The second indicator of the 1st trimester screening norm is visualization of the nasal bone. If it is not visible during the examination, then this indicates a possible risk of Down syndrome of 60-80%, but it is believed that in 2% of healthy fetuses, it may also not be visualized at this stage. By 12-13 weeks, the normal size of the nasal bone is about 3 mm.

During an ultrasound at 12 weeks, the age and approximate date of birth of the child are determined.

1st trimester screening - interpretation of blood test results

A biochemical blood test for beta-hCG and PAPP-A is deciphered by converting the indicators into a special MoM value. The data obtained indicate the presence or absence of deviations for given period pregnancy. But these indicators can be influenced by various factors: the age and weight of the mother, lifestyle and bad habits. Therefore, for a more accurate result, all data is entered into a special computer program, taking into account the personal characteristics of the expectant mother. This program shows the risk level results in ratios of 1:25, 1:100, 1:2000, etc. If we take, for example, option 1:25, this result means that for 25 pregnancies with indicators like yours, 24 children are born healthy, and only one with Down syndrome.

After the 1st trimester blood test is screened and based on all the final data received, the laboratory can issue two conclusions:

1. Positive test.
2. Negative test.

In the first case, you will have to undergo a more in-depth examination and... In the second option, additional studies are not needed, and you can calmly wait for the next scheduled screening, which pregnant women undergo during the 2nd trimester.