Ultrasound at 12 weeks of pregnancy: fetal size and other features

Many expectant parents use an ultrasound at 12 weeks of pregnancy to get their first close-up view of their unborn child. This scan is a thrilling time because it gives us a look at the developing fetus and gives vital information about its growth.

At this point, the ultrasound can determine the baby’s size, monitor the heartbeat, and evaluate the pregnancy’s general health. At twelve weeks, the fetus is typically two inches long, or the size of a lime, and several important characteristics have started to develop.

This scan is crucial for making sure everything is going according to plan and for early detection of possible problems. It’s a significant first trimester milestone that gives many parents comfort as they get ready for the months to come.

The objectives of the examination

Part of the screening to determine the possibility of potential genetic pathologies includes an ultrasound study at the end of the third month of pregnancy. When combined with the blood test performed on the expectant mother, this examination technique yields useful information that can be used to determine the individual risks of conceiving a child who has developmental defects.

Prenatal screening is often planned for one of the days that fall between 11 and 13 weeks of pregnancy. The best period of time for diagnostics is 12 weeks because this is when all indicators that the doctor is interested in at this point have the highest information content.

Right now, ultrasound enables you to:

• identify markers that indirectly indicate the likelihood of the child having Edwards syndrome, Turner syndrome, Down syndrome, Cornelia de Lange disease, Patau syndrome, neural tube anomalies that lead to pathologies of brain development;
• check the gestational age, determine the expected date of birth;
• find out the specific features of a particular pregnancy – is it multiple or normal, complicated or not;
• find out how the fetus feels, assess its vital activity, size, compare them with the development norms inherent in a given period;
• to identify problems with the mother"s reproductive health, if any, – to exclude the threat of miscarriage, detachment of the ovum and other pathological conditions.

Method of implementation and preparation

A 12-week ultrasound exam is frequently referred to as a genetic ultrasound. The way you’re approaching it is appropriate. Expectant mothers look forward to the day of examination with both excitement and anxiety because the word "screening" conjures up images of horror and anxiety. Since this ultrasound is identical to other diagnostics of a similar nature, experts feel that there is no reason for concern. It will all be easy, comfortable, and painless.

The accumulation of intestinal gases at this time can cause the pelvic organs to "push back," compressing them and potentially affecting the ultrasound’s results. Thus, you should avoid eating cabbage, legumes, and carbonated water a few days prior to the screening exam. You should take "Simethicone" or "Espumisan" a few hours prior to visiting the doctor. These medications will assist in getting rid of any leftover intestinal gas and getting ready for the test.

At 12 weeks, an ultrasound and a laboratory blood test from a vein are performed on the same day. The purpose of the lab blood test is to measure the amount of hormones and proteins needed for the baby’s normal development and the proper progression of the pregnancy. The results of this analysis, which is conducted using the biochemical research method, can be influenced by food and the mother’s bad habits, such as smoking.

Doctors advise against women eating fatty foods, fried, smoked, or highly spiced foods, as well as sweets, two to three days prior to the exam in order to obtain more accurate results.

You should arrive at the consultation on an empty stomach on the day of the examination. The woman weighs herself, measures her height, and provides the attending physician with all relevant medical history prior to this ultrasound, including information about past illnesses, pregnancies, and births.

At this point, transvaginal ultrasound scanning, also known as "internal ultrasound," is the primary method used for ultrasound scanning. The vaginal wall allows the doctor to access the review without entering the bladder, so there’s no need to fill it. The transabdominal method of diagnosis, which involves moving an external ultrasound sensor along a woman’s abdomen to obtain an image through the anterior abdominal wall, is thought to be borderline applicable at 12 weeks.

The doctor will determine the best course of action, and a number of factors, including the expectant mother’s body type, may come into play. In the event that the woman is overweight and her stomach has a discernible "layer" of fat, the doctor will probably opt to perform the examination vaginally. At this point, thin patients are more likely to undergo an abdominal ultrasound. Occasionally, the physician may employ both techniques.

What can be learned?

At this point, the baby has arms and legs and resembles a tiny person quite a bit. The embryo’s tail has entirely detached itself. On the arms and legs, fingers have split apart. This week, the finger pads develop distinct characteristics, such as an imprint or distinctive pattern.

All of the baby’s internal organs are fully developed, and many of them—including the heart, pituitary gland, intestines, liver, and kidneys—have already started to function. The fetus itself is already 14–15 grams in weight and between 45 and 80 mm in height on average. The infant is highly energetic and has mastered the use of his hands; he can play with them by holding onto the cord or by sucking his finger. He will undoubtedly demonstrate to the expectant mother the potential of her developing child if the ultrasound diagnostician "caught" him engaging in these activities.

Since the baby’s external genitalia have already developed, the doctor can already attempt to determine the baby’s sex if it is in a favorable position. Should the mother be carrying twins or triplets, the physician will be able to assess and measure each baby’s measurements.

Not every consultation has access to a high-resolution, detail-rich modern ultrasound scanner, so not all of the aforementioned conditions can be observed at 12 weeks.

However, any device available now will be able to display the fetus’s movements, allow the mother to hear the heartbeat, and make determining the fetus’s size simple.

Throughout the process, the physician will undoubtedly assess the likelihood of genetic disorders based on indicators that are specific to them (visual cues). Furthermore, he will provide an assessment of the mother’s health and advise you on what to do in the event that miscarriage poses a threat. However, at this point, miscarriage usually disappears, the mother and fetus’s conditions return to normal, and toxicosis starts to recede.

Deciphering results

At the end of a 12-week ultrasound, it is impossible to determine whether the child has a chance of genetic pathologies, many of which are fatal and the rest of which just do not leave the chances of healing the peanut. As a result, medical professionals are deciphering screening data by contrasting what they observed on the scanner screen with the findings of a biochemical analysis of a pregnant woman’s blood.

As a result, you shouldn’t anticipate learning the baby’s health following an ultrasound. When the laboratory tests are ready, I’ll have to wait. The woman will receive a research protocol after visiting the ultrasound diagnostics room, in which the fundamental details of the pregnancy’s development will be "encoded" using letter and number abbreviations. Together, let’s examine the meanings of these acronyms and the customs that apply to this particular gestational week.

The protocol commences with an explanation of the study’s methodology and includes a date of the first day of the last menstrual cycle, which is used to compute the obstetric period and the date of birth. The general overview of what the physician observed is then explained. It is required to indicate the number of fetuses in the uterus along with whether or not they are viable and exhibit heartbeats.

The measurement from the crown to the tip of the coccyx, known as the coccygeal-parietal size, or CTE, is a crucial parameter that helps us determine the baby’s gestational age and development rate. Its average values for this week are shown below.

Table of CTE requirements for the 11–12 and 12–13 week periods:

Gestational age (week + day)	Coccygeal-parietal size (CTE), mm – norm	KTR – fluctuations within the normal range, mm
11+1	44.7	38.6 – 50.8
11+2	46.3	40.2 – 52.5
11+3	48.0	41.8 – 54.2
11+4	49.6	43.4 – 55.6
11+5	51.3	45.0 – 57.6
11+6	52.9	46.5 – 59.3
12 weeks exactly	54.6	48.0 – 61.1
12+1	56.3	49.6 – 62.9
12+2	57.9	51.0 – 64.5
12+3	59.5	52.7 – 66.0
12+4	61.0	54.3 – 67.6
12+5	62.6	55.7 — 69.5
12+6	64.0	57.1 -71.0

The fetal heartbeat is described in the following way. There’s a number added to the heart rate abbreviation, HR. The baby’s heart rate is indicated by this number. An average of 162 beats per minute is regarded as normal at this point. A value in the range of 150 to 175 beats shouldn’t cause concern.

The doctor will definitely report this if he feels that the baby’s heart beats too frequently, unevenly, or slowly and he does not like the frequency. You shouldn’t "wind yourself up" over trifles if this wasn’t announced.

The examination of chromosomal pathology markers is the primary task for which the screening is done, after which the doctor proceeds. At this point, ultrasonography only shows two such signs: the nasal bones (which are best visualized and measured). The thickness of the collar space (TVP).

Children with different genetic diseases have a discernible thickening of the space between the skin and the muscular skeleton on the back of the neck as a result of the accumulation of fluid in this area. For instance, newborns with Down syndrome typically have shorter necks.

TVP as an indicator is only useful at this point; after 14 weeks, it cannot be determined and is therefore useless. Due to the flattening of the nasal bones caused by various genetic pathologies, children with severe developmental anomalies may have very small or nonexistent nasal bones. Additionally, this marker may suggest potential issues.

Length of the nasal bones and thickness of the collar space at 12 weeks:

Age at gestation

TVP, mm

Nasal bones, in millimeters

1.6; ranges from 0.8 to 2.4

2.3, with a range of 1.8 to 2.9

1.6; ranges from 0.8 to 2.5

2.4, with a range of 1.8 to 3.1

Anatomy of the embryo (fetus) is described in a separate column. This area will only have "+" or "-" symbols instead of numbers, indicating whether or not the fetus has this organ. The physician may also enter information about the identified pathology or mark something as "normal," "no special features," or "examined."

The cranial vault, the major brain structures (the "butterfly"), the spine, a 4-chamber section of the heart, the baby’s abdominal wall, stomach, bladder, fetal stomach, and intestines are all examined at 12 weeks to complete this portion of the research protocol. The doctor will note that they have been checked and are normal if there are two arms and the same number of legs. The number of limbs is counted individually.

Resolute The placenta in the chorion is young and hasn’t had much time to form. Which uterine wall the "baby’s place" is fixed on is determined. Although the chorion is typically found on the back wall, its appearance on the front wall shouldn’t be alarming in the slightest. It is possible to determine whether placentation is adequate, low, or present by measuring the distance between the internal os and the chorion.

Determining the placenta’s thickness is essential. Its unusual growth may also be a sign of genetic disorders or fetal infection. Indicators typically range from 14.5 to 15.5 mm during this time.

In addition to measuring the length of the cervix and determining whether everything is normal, the ultrasonography diagnostician must evaluate the state of the uterus, appendages, and ovaries and determine whether there is a risk of pregnancy termination.

Gender determination is not one of the required screening criteria. A woman must pay the antenatal clinic’s tariff for the provision of paid services (within 500 rubles) if she wishes to ask a doctor this question. At this point, no doctor can, however, guarantee that the sex will be accurately determined. Given how similar they are, there is too much chance that someone will confuse a girl’s genitalia for limbs or the umbilical cord, making it difficult to recognize or tell one from the other.

Skilled physicians are able to see the sex. In the first trimester, the "prediction" has an accuracy of 75–80%. When you have your next scheduled ultrasound examination in 18–20 weeks, you will be able to see the sex more clearly.

Possible problems

During the 12-week ultrasound, certain anomalies and issues could be found. The most typical circumstances

• CTE is less than normal. The reasons for such a deviation may lie in later ovulation, that is, the fetus is younger than the doctor and the pregnant woman herself think. In this case, another ultrasound is prescribed in 1.5-2 weeks. A significant deviation of this value from the existing average standards may indicate developmental problems that can be a consequence of bad habits, poor nutrition of the pregnant woman, as well as a deficiency of the hormone progesterone in her body. With a decrease in the coccygeal-parietal size, congenital pathologies of a genetic nature are not excluded. In this situation, additional research is needed.

• No nasal bones or they are smaller than normal. The absence of nasal bones (aplasia) or their small size increases the risk of developing a baby with chromosomal abnormalities, but the accuracy of ultrasound as a diagnostic method does not always allow us to judge the presence of pathology. The doctor may not see the nose due to outdated equipment with low resolution. In addition, a small nose can be a hereditary individual trait if one of the parents has a small nose – a "button".

The cause will be determined by the outcomes of a control ultrasound in a few weeks and a biochemical blood test.

• TVP is higher than normal. A slight excess of this value should not cause alarm. Experts consider it "critical" if the size of the collar zone is 6-8 mm above the upper limit. In this case, the woman is referred to a geneticist for consultation, additional invasive methods are prescribed – chorion biopsy or amniocentesis, in order to identify pathology with 99.9% accuracy or refute suspicions. A significant excess of the parameter should be supported by changes in the blood formulas, in particular a high level of hCG and a reduced level of the PAPP-A protein.

• Low placentation, presentation. Of course, these conditions are quite dangerous in terms of the possibility of losing a pregnancy, but the prognosis is positive in most cases, because the uterus grows every day, and along with the stretching of the uterine walls, the placenta also rises (at 12 weeks – the chorion). The woman is prescribed a gentle labor regimen, bed rest may be indicated in case of presentation. A woman is prescribed drugs that have a positive effect on vascular permeability (“Actovegin”, “Kurantil”), as well as vitamin complexes developed specifically for expectant mothers.

• Threat of miscarriage, retrochorial hematoma. With such problems of bearing the pregnancy, the results of ultrasound at this stage only confirm the alarming symptoms that the woman experiences – these can be bloody or serous discharge, as well as pain in the lower abdomen and in the lumbar region. In this case, the decision on treatment is made by the obstetrician-gynecologist, who either sends the woman to the hospital to maintain the pregnancy, or gives recommendations for treatment at home if the hematoma (detachment of the ovum) is not extensive.

Overall, there is a good prognosis; 95% of women are able to carry their pregnancy to term and deliver a beautiful, healthy baby on schedule if they adhere to all of the doctor’s instructions and practice self-care.

Accuracy of the study

A woman can read that the study’s findings do not ensure that her child will be born healthy in the last section of the protocol during a screening ultrasound. So the question is, if there’s no clarity, why go through screening? The truth is that ultrasonography is not thought to be a completely accurate technique; the error and "for error" correction ranges from 10% to 15%. As a result, ultrasound accuracy at this point is roughly 90%. Accuracy in identifying the baby’s sex at 12 weeks is only 75–80%.

At this point, the goal of ultrasound diagnostics is not to make a specific diagnosis for the mother or child. Diagnostics only helps to make a broad assessment of the likelihood that a particular woman will give birth to a sick child, and it also lets you keep track of how quickly a tiny person is developing. The ultrasound’s conclusion cannot tell whether a woman is carrying a sick child because it is not taken into account in isolation from the blood biochemistry results.

Aspect	Description
Fetal Size	At 12 weeks of pregnancy, the fetus is typically about 2.1 to 2.5 inches long from crown to rump and weighs around 0.5 ounces.
Development	The fetus"s major organs are beginning to form, and its limbs are well-developed. The facial features are becoming more distinct.
Heartbeat	By this stage, the fetal heartbeat can usually be detected with an ultrasound, often appearing as a fast, rhythmic pulse.
Ultrasound Purpose	Ultrasound at 12 weeks helps confirm the pregnancy, check fetal growth, and screen for any potential abnormalities.
Measurement	Ultrasound measurements taken at this stage help determine the estimated due date and assess fetal development.

The 12-week ultrasound, which provides a first-hand, in-depth look at the developing baby, is a significant milestone in the pregnancy. It gives parents information on the baby’s development as well as vital health indicators like movement and heartbeat.

The size of the fetus, which is typically between 5 and 6 cm long, is measured during this scan to help medical professionals determine the due date. The scan provides an opportunity to clearly view the baby’s arms, legs, and head as they form and looks for any early indications of any developmental problems.

This ultrasound provides a comforting window into the baby’s development in addition to being a means of measuring size. Parents have a unique chance to bond with their child and learn about their health and development at this early age.

An ultrasound at 12 weeks of pregnancy offers crucial information about fetal development. It measures the baby’s length, which is usually about 2 inches, and looks for important characteristics like the heartbeat, limb movement, and organ formation. With the aid of this scan, medical professionals can evaluate the baby’s growth, identify any possible problems early on, and reassure expectant parents.

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