Determination of the nuchal transparency of an embryo using ultrasound

introduction

The Neck fold measurement belongs next to one Blood test to the one offered by many gynecologists today First trimester screeningwhich one too FiTS (First-Trimester-S.screening) is called. With the help of the neck fold measurement you can even before the birth any existing genetic disorders of the unborn child are identified.
This suspicion can then be confirmed by further examinations.

Why neck fold measurement?

The fear of a developmental disorder in her unborn baby accompanies every expectant mother.
Especially women older age are very much influenced by this fear, as these mothers have a higher risk of having a child with a malformation.

One way of assessing child development is to measure the crease in the neck.

Since this examination takes place before the birth, this type of examination is classified as the so-called Prenatal diagnostics (pre = before) to.
The measurement does not take place within the scope of the usual CheckupsThe mother must explicitly consent to the examination after she has been informed by the gynecologist about the pros and cons of this examination.

It takes place as Ultrasound examination in addition to the two legally prescribed ultrasound examinations, in which other structures of the child are measured in order to detect any developmental disorders.

When measuring the neck folds, above all Chromosomal disorders as the Trisomy 21 (= Down syndrome) as well as various other syndromes or Heart defect possibly diagnose. The Prenatal test, however, a confirmation biopsy must be performed for all diagnostic procedures.

The fact that "Non-provisionIt is also due to the examination that the sometimes very high costs of up to € 200 have to be paid out of your own pocket and are not covered by statutory health insurances.

The decision FOR the examination is strongly recommended for mothers in whom small changes and deviations were noticed during the usual preventive examinations in previous ultrasound examinations, in pregnancies with a maternal age of over 35 years or at High risk pregnancies.

Since one is considered to be a high-risk pregnant woman from the age of 35, as the risk of malformations increases with the age of the mother, the health insurers often even cover the costs of this examination in this case.

What is being done?

When measuring the neck crease, as the name suggests, the child's neck crease is assessed.

The skin in the neck area is assessed using ultrasound.
The terms of neck density measurement and the Neck transparency measurement describe other structures of the neck fold examined in addition to the thickness.

The neck area of ​​the unborn child is assessed by means of an ultrasound examination.
The examination itself is very straightforward and very low-risk for both mother and child and does not pose any greater risk than the other ultrasound examinations during the preventive routine.

The ultrasound is either through the Scabbard the mother or about the Abdominal wall carried out, depending on the position in which you can best assess the child's neck.

The thickness is measured by Water retention in the neck fold and its shading in the ultrasound image.

Ultrasound consists of emitted sound waves similar to the echo sounder on ships.
The sound waves cannot be heard by humans because the human ear cannot hear all the sound waves by far.
The waves emitted are reflected by surrounding boats during shipping, as they bounce off them and are thrown back.
A boat can then use the signals returned to identify which boats are in its vicinity.

This principle works in the same way with ultrasound examinations in medicine. Those of different Tissues Reflected and reflected waves can be picked up by the ultrasound device and the image of the child calculated from the reflected waves from the device is displayed on the screen.

Different types of fabric reflect the waves to different degrees, so the different waves reflected are shown in different colors on the screen.
The color can then be used to draw conclusions about the fabric to a certain extent.

Liquids hardly reflect rays and appear black on the screen of the ultrasound device, for example this Amniotic fluid.
An otherwise light tissue can appear darker if there is liquid in it.

Exactly this property is used here, because the fetus fluid collects in the tissue.
The reason for this are the Kidneys and Excretory organswhich are not yet sufficiently mature in the fetus. For this reason, the liquid is still deposited in the tissue. The liquid itself is completely safe for the child, that is what counts amount the stored fluid and a possibly widened thickness of the neck fold due to the deposits.

Measurements are taken several times during the examinations and an average value is then determined. The liquid, which is transparent in the ultrasound, gave the examination the name of the neck transparency measurement.

The terms NT measurement, neck fold measurement and neck transparency measurement are all used equally.

When is a neck fold measurement carried out?

Neck wrinkles are usually measured during the first trimester screening between the 11th and 14th week of pregnancy. During this time, a thin line of liquid forms in the child's neck, which can be seen as a bright spot on the ultrasound. As organs mature in the course of pregnancy, the fluid accumulation on the neck disappears again.

In the ultrasound one would then see no or only a very minimal "neck fold". Statements from an examination after the 14th week of pregnancy would therefore not be conclusive. Even before the 10th week of pregnancy, neck fold measurements should not be carried out, as the baby is still too small and the values ​​could be incorrect.

The optimal time for a neck wrinkle measurement would be around the 12th week of pregnancy.

Read more on the topic: 1st trimester of pregnancy

When do you measure?

The time window between the 11th and 14th week of pregnancy.
Before that, the fetus is still too small and the results cannot be evaluated. Later, the fluid is drained from the better and better functioning kidneys Lymphatic system of the child until it is no longer visible in the ultrasound at some point.

What does the measurement say?

Normally the thickness of the water retention in the neck fold in a healthy fetus is 1mm to 2.5mm.
From 3 mm one speaks of increased values, from 6 mm of strongly increased values. If abnormal results are measured in the examination, a definitive diagnosis of certain malformations cannot be made.

One can only determine the probability of a malformation via the extent of the water accumulation.
A change in the neck fold occurs in the context of various developmental disorders such as Down syndrome and Edwards syndrome (Trisomy 18) or in the case of heart defects.

It is not uncommon for children with abnormal neck folds to be born completely healthy and without any developmental changes!

Therefore, if you find abnormal findings, you should never immediately assume that a child will be born with a severe disability, even if most women immediately fear the worst.

In most cases, the pregnant woman's blood is also examined, because the blood test and ultrasound result together give more precise information about a possible malformation.
In this so-called triple test, various parameters such as the pregnancy hormone B-HCG are measured.

Like the ultrasound examination, the measured values ​​only allow a purely statistical statement about the probability of a malformation with a certain neck fold thickness.

Nevertheless, it is used frequently and with great reliability, because 80% of children with trisomy 21 can be successfully diagnosed here just by measuring the neck folds alone.

By combining the neck fold measurement with the above-mentioned blood test, this probability can be increased up to 90%.
Conversely, however, it should also be noted that 20% of all children born with trisomy 21 had an unremarkable crease in the neck when examined.

However, further investigations are necessary if there is any suspicion.
An amniotic fluid test (=Amniocentesis), an examination of the umbilical cord and a chromosome examination can then bring the final answer.

In chromosome analysis, cells from the unborn child are obtained and examined using one of the types of examination mentioned above. However, these examinations are no longer as low-risk as the simple ultrasound examination and the risk of infections for mother and child due to the decrease in amniotic fluid increases.

If an undesirable development is actually diagnosed, it is important to give the parents support and assistance in order to be able to adequately accompany a possible termination of pregnancy or the preparation for a life with a disabled child.

Parents must then be informed about alternatives such as operations on the unborn child, adoption or abortion and the consequences.
No matter what decision the parents make, they should be given appropriate support.

If a heart defect is diagnosed as a result of the investigation, the latest advances in medicine must always be pointed out.
In the minds of many people, heart defects are still the death sentence for a newborn, but on the contrary, in most cases they are operable with high success rates and thus almost curable.

Heart defects can often be carried out without a blood sample or amniotic fluid extraction, and a 3D ultrasound or a so-called Doppler examination can be meaningful enough.
The Doppler examination is also carried out as part of an ultrasound examination and uses ultrasound waves to measure the blood flow in the vessels of the unborn baby according to the same principle as above.
Most heart defects can then also be assessed or excluded with this.

Result of the neck fold measurement

The Neck fold measurement takes place with the help of high-resolution ultrasound devices, which have the ability to measure the density of the neck fold. These values ​​are usually related to the size of the unborn child (crown-rump length) and the age of the mother and then compared with reference values.
For example, neck fold values ​​apply about 2.1mm in a 45mm child as a trisomy-suspicious.
For 85mm children, the thickness should not be more than 2.7mm be.

Higher values ​​would also indicate a malformation of the child. If, in addition to the abnormal measured values, the mother's age is also increased (over 35 years), the probability of a possible malformation of the child is high.
Ultimately, however, one has to say that the neck fold measurement alone Not sufficient for a diagnosis. Even healthy children can have thickened neck folds without a malformation. A neckfold measurement would incorrectly diagnose these as sick, even though they are actually healthy.

Studies have shown this - 6 out of 100 Children were diagnosed as sick even though they were healthy. With the help of further examinations (e.g. an amniocentesis (Amniotic fluid examination) or one Chorionic villus sampling) this misunderstanding can ultimately be clarified. This is to show that a neckfold measurement, although it is very safe per se, can also lead to misinterpretations.
For this reason, it should be viewed more as a probability determination than a final diagnostic option. However, since it provides a high level of certainty in diagnosing a malformation and, compared to other examinations (such as amniocentesis and chorionic villus sampling), it does not pose any risks for mother and child, neck fold measurement is the first choice as a screening method.

Heart malformations and metabolic diseases can also be reliably recognized by them.

Neck fold measurement and gender determination

Usually from the 15th week of pregnancy the child's reproductive organs are so well developed that during this period the sex (for sure) can judge.

The structure of the penis can usually be seen earlier and more clearly than the development of the clitoris in girls. Since the neckfold measurement usually takes place earlier (10-14 weeks of pregnancy) it is not always possible to determine the gender at this point in time. In some cases, however, the children develop so quickly that in some cases (especially with boys) can see the gender as early as the 13th week of pregnancy.
This could then also be determined during a neck fold measurement.

Who measures the crease in the neck?

In principle, the examination can be carried out by any doctor with permission to measure the neck folds.
Doctors can get through every year Quality controls also develop a certificate.
However, since a special high-resolution ultrasound device is necessary, a visit to one is often necessary Special practice necessary if you have decided to carry out the neck fold measurement.

Twins pose a major problem for the gynecologist even during routine ultrasound examinations as part of preventive care Challenge.

Of course, this challenge also arises when measuring the neck folds. Nevertheless, a twin pregnancy is not an exclusion criterion for the measurement, it only poses a more or less great challenge for the examiner and a greater expenditure of time due to the double measurement.

It should be noted that the values ​​in twins can differ to a greater extent if the two fetuses do not grow in the same way.

Cost of a neckfold measurement

The neckfold measurement is not part of the normal preventive examinations for pregnant women and is therefore used in most pregnant women NOT paid for by health insurers. Pregnant women under 35 years of age would usually have to bear the costs for the examination themselves.

Since the neck fold measurement as Hedgehog- If the service is offered by the gynecologists, the prices for this can vary considerably. These can be between 30 € and over 200 € lie. However, since there are always health insurance companies that cover the costs, it is worth checking with your health insurance company beforehand. Pregnant women over 35 years of age, on the other hand, are urgently advised to measure the neck folds, as their age already poses an increased risk of a child's malformation (e.g. Trisomy) to have.
In these cases, the examination is covered by the health insurance.

Alternatives to neck fold measurement

As alternatives to neck fold measurement are the Amniotic fluid examination and blood tests of the mother, can be extracted from the child's genetic material and thereby e.g. Chromosomal abnormalities such as trisomy 21 can be reliably detected from the 12th week of pregnancy.