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Tests during the pregnancy


Screening for chromosomal anomalies / Down syndrome:

Maternal serum triple markes:

Meaning of results - The result of the screening test is obtained as a weighted risk taking your age and the results of the tests you have undergone into account. It predicts the statistical risk: one out of a number of women of the same age having an identical result in...

Elevated alpha-fetoprotein (fetal protein) in the mother's blood biochemical screening test - The level of alpha-fetoprotein in the mother's blood is considered to be elevated if it is more than 2.5 times the average in a singleton pregnancy, and more than twice the average in a twin pregnancy. It can arise from a number of causes...

A low estriol level in the mother's blood biochemical screening: Ichthyosis and other possibilities - A very low level of estriol in the mother's blood is associated with a number of medical conditions for which testing is available. The most common is a skin disease known as ichthyosis. The main manifestation of this disease is scaly skin, particularly..

High hCG level - The normal range is 0.2-3 MoM (multiples of the median). High levels indicate a statistically increased risk for Down syndrome which is expressed in the calculated weighted statistical risk. If amniocentesis is performed, this will confirm or rule out...

Nuchal translucency - This is an ultrasound test in which the thickness of the fluid accumulated in the region of the base of the fetus's head is measured. In order to obtain maximal accuracy, a vaginal electrode (inserted into the birth canal) should be used to perform...

Why is there no medical recommendation for amniocentesis in all cases? - Amniocentesis (and chorionic villus sampling) is undoubtedly the only test that can categorically rule out chromosomal disorders. However, it is neither medically indicated nor recommended that every pregnant woman should undergo amniocentesis...

Identifying women at increased risk of having an infant with Down syndrome - The sole parameter that was used in the past for evaluating the risks of having an infant with a chromosome abnormality was the mothers age. Amniocentesis was recommended for women over the age of 35, but despite these efforts, no significant decrease...

What is biochemical screening for the detection of Down syndrome? - These tests are aimed at identifying within the population of pregnant women those who are at high risk of having an infant with Down syndrome and other congenital defects. They are screening rather than diagnostic tests. The difference between them...

Ultrasound findings:

Soft signs

Failure to detect the Gallbladder on Ultrasonography - The gallbladder, like any fluid cavity, can be clearly observed on ultrasound examination. Failure to detect the gallbladder ultrasonographically is rare, and usually in these cases a repeat test (often involving a number of repetitions)...

Small stomach or failure to detect the stomach on ultrasonography - The stomach, like any fluid cavity, can be clearly observed on ultrasound examination. Sometimes it can appear to be small, but on further examination at a later stage it will appear normal. However, if repeated ultrasound examinations consistently...

Short femur - The length of the femur (thigh bone) usually corresponds with the week of pregnancy plus or minus one week. A reduction in the length of the femur of greater than one week can arise from a number of conditions: Inaccurate determination of the week...

Unilateral renal agenesis (absence of one kidney) - The kidneys develop in the region of the urinary bladder and ascend/migrate upwards to their location in the rear of the abdominal cavity. Most of us have 2 kidneys, but sometimes only one can be found on ultrasound scanning...

Dilated renal pelvis - Urinary tract disorders are common. They occur in a large percentage of the population, are generally mild, and usually have no significant clinical implications. Major defects are relatively rare. On each side of the body there is a kidney...

Macrocephaly/megalencephaly (increased head circumference) - A larger than average head circumference for the week of pregnancy (more than one week's difference) is a relatively common finding and has no medical significance if the fetus's head circumference is in the normal range, especially if one of the...

Oligohydramnios (too little amniotic fluid) - A mild degree of oligohydramnios causes no direct detrimental consequences to the fetus. However, severe oligohydramnios does have severe consequences for the fetus, irrespective of cause. In the uterus, the swallowing of water by the fetus promotes...

Polyhydramnios (excess amniotic fluid) - Polyhydramnios is a subjective finding evaluated by the examining ultrasonographer. It occurs in 1% - 3% of pregnancies and is especially common in twin pregnancies. In most cases, it appears at the end of the second trimester or during the...

Nuchal edema (thickened nape) and/or cystic hygroma - This is edema of the fetus's neck caused by an accumulation of fluid, usually lymph. Usually lymphatic fluid collects at this site and is absorbed into the bloodstream. However, a delay in the development of the system that drains the fluid into...

Nuchal Cysts (cysts in the fetus's neck) - Small cysts in the sides of the fetus's neck are usually the result of a delay in the formation of the blood vessels that drain the lymphatic fluid. It occurs in about 1% of pregnancies. When it appears in the first trimester of pregnancy...

Echogenic Bowel - On ultrasound examination, the normal intestine appears gray/black, but an echogenic bowel has a bolder appearance. The echo returned from the ultrasound is more marked and the intestine appears whiter than the other abdominal organs...

Two blood vessels in the umbilicus (single umbilical artery) - Usually the umbilical cord has two arteries that bring blood to the fetus and one vein that returns the blood to the placenta. However, in 1% of pregnancies there is one vein and only one artery. This can arise as a result of clotting and obliteration...

Echogenic focus in the fetus's heart (golf ball) - An echogenic focus is an ultrasound reflection of the thickening of one of the tendonous cords that hold the heart valves. Such a thickening does not interfere with the normal functioning of the valves and it has no significance for the structure...

Choroid plexus cyst - On a cross-sectional scan using the ultrasound transducer it can be seen that the brain is divided into two hemispheres. Within each hemisphere there is a ventricle (cavity or chamber) that contains fluid that lines and protects the surrounding...

Micrognathia (very small jaw) and Pierre Robin sequence - Some cases of micrognathia, usually when it is an isolated finding, are transmitted by autosomal dominant inheritance. In Pierre Robin sequence, because there is a very small jaw the tongue is retracted and this interferes with the closure of the...

Any organ not demonstrated by ultrasound - Sometimes it can happen that some organs cannot be demonstrated by ultrasound examination. This can be because the pregnancy is a week earlier than estimated, or because the fetus is in a position that precludes completion of the examination. Sometimes...

Echogenic foci or calcifications in the umbilical cord, abdomen or stomach - Echogenic foci in the various organs appear on ultrasonography as focal white spots. Such a focus can indicate an area of calcification or be a transient event in that tissue. It is common to see such foci in areas of organization of and recovery from...

Placental problems: cysts, hematoma (bleeding), partial placental separation, large/thick placenta - Various problems can occur in the placenta: Cysts, Hematoma, Partial, separation, Thick placenta and/or placental tumors. Clinical signs - These are cysts in the placenta that contain fluid. This can be old blood or a different fluid...

Failure to demonstrate the fifth middle phalanx - Each of the fingers apart from the thumb has 3 sections, called phalanges. Sometimes ultrasound examination of the fifth finger fails to demonstrate the middle phalanx – this is a result of delayed ossification, i.e. delay in the deposition of...

Anomalies

Clubfoot - This is an inversion of the foot of variable severity. It is relatively common, occurring in approximately 1 in 500 fetuses. In most cases it is an orthopedic problem that does not involve other organs. In cases in which this is the sole finding...

Bilateral renal agenesis or severe renal hypoplasia (absence of both kidneys or undeveloped kidneys) - Bilateral renal agenesis occurs in 1 out of every 4000 births, and it results in fetal death because of inadequate lung development. The lack of formation of urine causes a marked reduction in the amount of amniotic fluid, and this leads to...

Neural tube defects - NTD - Neural tube defects are defects in the closure of the spinal column or in the development of the brain. They occur at a very early stage of embryonic development and are a result of the failure of the neural canal to close properly...

Polydactyly (supernumerary digits) - Polydactyly (6, 7 or more digits per limb) can occur in one or more limbs. From a medical viewpoint, 2 main types are distinguished: An extra digit on the little finger/toe side (postaxial). An extra digit on the thumb/big toe side (preaxial)...

Situs inversus - Full (complete) situs inversus - the heart and abdominal organs are completely reversed, i.e. the apex of the heart and the stomach are on the right. Partial (incomplete) situs inversus - the heart is on the right but the liver is usually in the center...

Syndactyly (fusion of digits) - Syndactyly can occur with or without polydactyly (supernumerary digits). The fusion can involve the skin between the digits or the entire digit, including fusion of the bones, which is demonstrable on X-ray, when the fused digit appears wider than...

Bilateral ventriculomegaly between 10 and 14 mm - On a cross-sectional scan using the ultrasound transducer it can be seen that the brain is divided into two hemispheres. Within each hemisphere there is a ventricle (cavity or chamber) that contains fluid that lines and protects the surrounding soft...

Ventriculomegaly (unilateral or bilateral) in excess of 14 mm and/or progressive ventriculomegaly - hydrocephalus - On a cross-sectional scan using the ultrasound transducer it can be seen that the brain is divided into two hemispheres. Within each hemisphere there is a ventricle (cavity or chamber) that contains fluid that lines and protects the surrounding soft...

Unilateral ventriculomegaly between 10 and 14 mm. - On a cross-sectional scan using the ultrasound transducer it can be seen that the brain is divided into two hemispheres. Within each hemisphere there is a ventricle (cavity or chamber) that contains fluid that lines and protects the surrounding...

Hypospadias - This is a common anomaly of the penis manifesting as an opening on the lower aspect instead of at its end. It is important to differentiate between several types: The isolated (non-syndromic) type, in which hypospadias is the sole finding...

Defect in the closure of the abdominal wall - Omphalocele and gastroschisis - This is a defect in the abdominal wall manifesting in the herniation of some of the intestines and possibly other organs too outside the abdominal wall. They protrude through the umbilicus (navel), through a ring that surrounds the umbilical cord...

Diaphragmatic hernia - This is a congenital defect of the closure of the diaphragm, which is the muscle that separates the abdominal and chest cavities.There are two main types, which are easily distinguished: Posterior diaphragmatic hernia and Anterior diaphragmatic hernia...

Pleaural effusion - Pleural effusion is an accumulation of fluid between the lungs and the external wall of the chest cavity. This fluid can contain: In most cases, lymphatic fluid - this type is known as a chylothorax. Watery fluid (clear, serous and noninflammatory)...

Irregularities or defects in the structure of the vertebrae - Many variations may occur in the structure of the vertebrae, and it is important to distinguish between these: Usually the defect is restricted to a single vertebra without other abnormalities. It is important to differentiate between the different...

Amniotic band syndrome - An amniotic band is a membrane formed in the amniotic cavity surrounding the fetus. This membrane may envelop and constrict the fetus to the point where organs or limbs entrapped in it can be amputated. The outcome and severity depend on the stage...

Sacrococcygeal teratoma - A teratoma, in general terms, is a tumor containing at least two of the three main layers of the fetus. In teratomas in the newborn/fetus, it is common to find a tumor composed mainly of nervous system tissue (almost always), fat, muscles, cartilage...

Multiple defects - The causes of multiple defects: Genetic disorders – various syndromes such as chromosomal syndromes (e.g. Down syndrome or another chromosomal syndrome), or genetic, non-chromosomal syndromes. There are more than 5,000 genetic syndromes...

Intrauterine infection:

CMV - Cytomegalovirus infects many adults during their lifetime. It usually manifests as inflammation of the upper respiratory tract, sometimes involving severe tonsillar pain, fever, fatigue, rashes, etc. In most cases, however, the illness is so mild...

Toxoplasma - Many infections (viruses, bacteria, etc.) can pass through the placenta and infect the fetus - this occurs when the mother has an infection caused by a specific infective agent, such as a virus. However, there are only five main pathogens...

Others

Invasive tests:

Amniocentesis - Amniocentesis is a test performed for the purpose of diagnosing genetic diseases (mainly chromosomal disorders) in the fetus. It is aimed at determining whether there are any abnormalities in the number and structure of the chromosomes, which contain...

CVS - As in the case of amniocentesis, this test is also performed for the purpose of diagnosing genetic diseases in the fetus. In this case, however, the sample is taken from the fetal cells in the chorionic villi of the placenta...

Cordocentesis

Others

Interpretation of the cytogenetic (chromosomal study of fetal cells (from amniotic fluid, etc…)

Chromosomal anomalies - general

Specific chromosomal anomalies

Down syndrome - This syndrome affects approximately 1:660 newborns, and is therefore considered to be the number one cause of mental retardation. The main features are mental retardation of varying degrees and characteristic facial features.The main clinical signs are...

Trisomy 18 - This syndrome is caused by the presence of an extra chromosome 18 - i.e. there are three number 18 chromosomes instead of the normal two. The syndrome results in death in 90% of infants either during pregnancy or before they are a year old...

Trisomy 13 - In this condition there is an extra chromosome 13, so that there are three number 13 chromosomes instead of two. The frequency is estimated to be 1 in every 5,000 births. This syndrome ends in death - 86% die in the uterus or in the first year of life...

Turner syndrome - This syndrome is caused by the absence of one X chromosome in females, so that these girls have only one X chromosome and a total of 45 chromosomes altogether...

Klinefelter syndrome (XXY) - This syndrome is caused by an extra X chromosome in males, so that these boys have two X chromosomes and one Y chromosome, giving a total of 47 chromosomes altogether...

XXX (triple X) syndrome - In this syndrome there is an extra X chromosome in addition to the two that are normally present in females, giving a total of 47 chromosomes altogether. About 70% of these female fetuses survive through to term (birth), and the frequency is 1 in 1,000...

XYY syndrome - This is the name given to the syndrome resulting from an extra Y chromosome in males. Normally males have one X and one Y chromosome, but a male with this condition has an extra Y chromosome, so that he has 47 chromosomes altogether. The frequency...

Trisomy 20 (mosaic) - The presence of 3 number 20 chromosomes instead of the normal 2, is only found in some of the amniotic and skin cells of the fetus and not in all. This situation, where there is a mixture of cells with normal chromosomes and cells with trisomy 20...

Reciprocal translocation - This is the exchange of chromosomal material between two chromosomes of different pairs. A translocation is said to be balanced when a change occurs in the location of certain genes, but there is no gain or loss of genetic material...

Robertsonian translocation - This is the exchange of chromosomal material between two chromosomes of different pairs. A translocation is said to be balanced when a change occurs in the location of certain genes, but there is no gain or loss of genetic material...

Molecular tests

New technology for molecular diagnosis - In preparation for the imminent birth, this information tells you about what tests, treatments and immunizations are performed routinely and constitute part of the overall management of both the woman about to give birth and the infant in the delivery...

Types of molecular tests

Testing the disease-causing gene for mutations that are common in a specific ethnic group - autosomal dominant diseases - It is preferable to start by testing patients in the family, if there are any. If the gene is found using this method, other family members carrying the same mutation, i.e. who are considered to be affected, can be identified...

Testing the disease-causing gene for mutations that are common in a specific ethnic group - autosomal recessive diseases - It is preferable to start by testing patients in the family, if there are any. If the defects (mutations) are found using this method, it is possible: To allow a couple that has had an affected child to undergo prenatal diagnosis to determine with...

Testing the disease-causing gene for mutations that are common in a specific ethnic group - X-linked diseases - It is preferable to start by testing patients in the family, if there are any. If the defects (mutations) are found using this method, it is possible: 1. To allow a couple that has had an affected child to undergo prenatal diagnosis to determine...

Finding the defect (mutation) by establishing the gene sequence - autosomal dominant diseases - The test is performed on the patients themselves. The mutation (the defect in the gene) can be determined in the patient by establishing the gene sequence. If the defect is found using this method, other members of the family who also carry the same...

Finding the defect (mutation) by establishing the gene sequence - autosomal recessive diseases - The test is performed on the patients themselves. The mutation (the defect in the gene) can be determined in the patient by establishing the gene sequence. If the defect is found using this method, it is possible...

Finding the defect (mutation) by establishing the gene sequence - X-linked diseases - The test is performed on the patients themselves. The mutation (the defect in the gene) can be determined in the patient by establishing the gene sequence. If the defect is found using this method, it is possible...

Screening test for identifying defects (mutations) using various methods such as SSCP - autosomal dominant diseases - The test is performed on the patients themselves – even if there is only one. The gene can be screened for a mutation without checking each and every one of its component bases. This is a short, simple and more rapid test than establishing the entire...

Screening test for identifying defects (mutations) using various methods such as SSCP - autosomal recessive diseases - The test is performed on the patients themselves – even if there is only one. The gene can be screened for a mutation without checking each and every one of its component bases. This is a short, simple and more rapid test than establishing the entire...

Screening test for identifying defects (mutations) using various methods such as SSCP - X-linked diseases - The test is performed on the patients themselves – even if there is only one. The gene can be screened for a mutation without checking each and every one of its component bases. This is a short, simple and more rapid test than establishing the entire...

Screening tests for identifying gene products for establishing the existence of a disease (methods such as protein truncation) - autosomal dominant diseases - The test is performed on the patients themselves – even if there is only one. These tests involve examining the soundness of the gene products,i.e. the proteins, without examining the sequence of bases, so that the mutation itself is not demonstrated...

Screening tests for identifying gene products for establishing the existence of a disease (methods such as protein truncation) - autosomal recessive diseases - The test is performed on the patients themselves – even if there is only one. These tests involve examining the soundness of the gene products,i.e. the proteins, without examining the sequence of bases, so that the mutation itself is not demonstrated...

Screening tests for identifying gene products for establishing the existence of a disease (methods such as protein truncation) - X-linked diseases - The test is performed on the patients themselves – even if there is only one. These tests involve examining the soundness of the gene products, i.e. the proteins, without examining the sequence of bases, so that the mutation itself is not...

Indirect testing for genetic markers in a family that has a number of patients - when there is only one gene that can cause the disease - autosomal dominant diseases - This is not a direct test, but a comparative one. The alleles (an allele is one member of the pair of genes at a given disease locus) that are common to patients are compared. The “shared allele” of the patients within the same family is the one...

Indirect testing for genetic markers in a family that has a single patient - when there is only one gene that can cause the disease - autosomal dominant diseases - This is not a direct test, but a comparative one. It is based on the fact that many patients with this inheritance pattern are the first ones in their family to be affected (a “new” mutation). Such individuals are known as probands...

Indirect testing for genetic markers in a family that has a one or more patients - when there is only one gene that can cause the disease - autosomal recessive diseases - This is not a direct test, but a comparative one. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared. The parents are both carriers...

Indirect testing for genetic markers in a family that has a one or more patients - when there is only one gene that can cause the disease - X-linked diseases - This is not a direct test, but a comparative one. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared in order to establish which of the...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - all genes having been located / identified / mapped - autosomal dominant diseases - This is not a direct test, but a comparative one, which is called linkage analysis. In genetic linkage studies, alleles of each of the genes being tested (an allele is one member of the pair of genes at a given disease locus) are compared between the...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - all genes having been located / identified / mapped - autosomal recessive diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - all genes having been located / identified / mapped - X-linked diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - not all genes having been located / identified / mapped - autosomal dominant diseases - This is not a direct test, but a comparative one, which is called linkage analysis. In genetic linkage studies, alleles of each of the genes being tested (an allele is one member of the pair of genes at a given disease locus) are compared between...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - not all genes having been located / identified / mapped - autosomal recessive diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared...

Indirect testing for genetic markers in a family that has a number of patients - when there are a number of genes that can each cause the disease - not all genes having been located / identified / mapped - X-linked diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared in...

Indirect testing for genetic markers in a family that has one or several patients - when there are a number of genes that can each cause the disease - the gene, or most of the genes not having been located / identified / mapped - autosomal dominant diseas - This is not a direct test, but a comparative one, which is called linkage analysis. In genetic linkage studies, alleles of each of the genes being tested (an allele is one member of the pair of genes at a given disease locus) are compared between...

Indirect testing for genetic markers in a family that has one or several patients - when there are a number of genes that can each cause the disease- the gene, or most of the genes not having been located/identified/ mapped- autosomal recessive diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared...

Indirect testing for genetic markers in a family that has one or several patients - when there are a number of genes that can each cause the disease - the gene, or most of the genes not having been located / identified / mapped - X-linked diseases - This is not a direct test, but a comparative one, which is called linkage analysis. The alleles (an allele is one member of the pair of genes at a given disease locus) that have been transmitted by the parents to the affected child are compared in...

Indirect testing for genetic markers in a family that has one or several patients - when there are a number of different genes that can each cause the disease - the gene, or most of the genes not having been located / identified / mapped - multifactorial - Ths is not a direct test, but a comparative one, which is called linkage analysis. In genetic linkage studies, alleles of each of the genes being tested (an allele is one member of the pair of genes at a given disease locus) are compared between the...

Disadvantage of the molecular tests - Molecular tests are considered to be, and usually are, precise. However, as in any other test, there are limitations in accuracy as specified below: Molecular tests involve the use of biological substances (enzymes) intended for research...

How is a molecular genetic test performed? - These tests examine the DNA sequence in a gene in order to determine whether or not a mutation is present. In the future, it may be possible to read the entire genetic sequence rapidly, effectively and cheaply. At present, however, the test is slow...

Biochemical enzymatic tests - These tests are used to diagnose diseases in which the exact enzyme deficiency is known and its activity can be tested (e.g. Tay Sachs disease, Gaucher's disease). The tests are performed on the tissue in which the protein is expressed. In several...

Special cytogenetic tests - In these tests, small deletions and duplications at certain sites in a gene or chromosome may be identified. These deletions and duplications cannot be identified using a classic cytogenetic (chromosome) test routinely performed on the amniotic fluid...

 

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