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Although there is no direct medical benefit of receiving an elective 3D ultrasound, there may be many indirect benefits, as listed below. It is important to note that there has been no conclusive evidence in the medical literature to support these benefits, and in fact, the medical literature shows conflicting studies on these benefits. However, on the individual level, a pregnant woman may find any of the following benefits for herself personally.
May reduce alcohol intake
Controversially, Christian/Catholic non-profit organizations have employed 3D ultrasounds for young pregnant women in order to influence their decisions regarding abortion. Charitable donations or public funds help pay for the 3D ultrasound machine.
Generally, the risks of 3D ultrasounds mirror those of 2D ultrasounds, as it uses the same ultrasound waves at the same intensity. Unlike the comparison of CT scans to x-rays, 3D ultrasounds do not employ multiple snapshots of 2D ultrasounds but uses the 2D ultrasound images taken at various angles to construct an image. So the potential risk of 3D ultrasounds, if any, would depend on the duration of the ultrasound session rather than whether it is 2D or 3D.
The risk of ultrasounds, theoretically, would depend on the following factors:
The 'wand' is then moved around your vagina to allow the technician to 'see' up into the uterus and abdomen as needed. Occasionally it needs to be pressed up on either side of your cervix firmly to 'see' the ovaries clearly, which can be a bit uncomfortable for some women, but the discomfort is usually tolerable. Some moms have likened a transvaginal ultrasound to 'having someone driving a stick shift inside.' That’s a crude but accurate description. Having a sense of humor about it makes it easier. However, women who have sexual abuse background may want to request a female technician instead or avoid having an early ultrasound altogether, depending on their comfort levels.
Generally speaking, the trans-vaginal ultrasound is used in the first trimester, since the uterus has not yet grown big enough to lift out of the pelvic cavity. It is very useful in getting a clearer picture to determine whether there is an ectopic pregnancy, whether the fetus is viable, if there are multiple fetuses, etc. It is especially useful in heavyset women and perhaps in women with a retrograde uterus.
Because the transducer is right up by the cervix and thus right next to the baby, the ultrasound waves do not have to go through the abdomen before reaching the baby, and the picture is often clearer than with an abdominal ultrasound at this point. However, it also means the transducer is much closer to the baby than with an abdominal ultrasound, and critics worry about the safety of this. Does the baby receive increased levels or intensity of ultrasound this way, and is this more harmful particularly because it is usually used during the first trimester? No one knows.
The closeness of the trans-vaginal transducer (and its ability to use somewhat higher frequencies) is a particular advantage in the case of very heavy women with extensive abdominal adiposity. Although abdominal ultrasounds definitely work on heavy women later on in pregnancy, sometimes they are not very effective earlier in pregnancy. Thus transvaginal ultrasounds are especially common in women of size early in pregnancy. However, it is also not unusual for women of all sizes (not just heavy women) to have difficulty getting a clear abdominal ultrasound early in pregnancy, so big moms should not feel like they are the only ones having a vaginal ultrasound. When ultrasounds are done in very early pregnancy, they are usually done transvaginally. It is only a little later that there is a difference in ultrasound method due to size and this does not last for long.
At some point around the end of the first trimester, most average-sized women can have an abdominal ultrasound done, but in some larger women, a transvaginal ultrasound may still need to be used for a few weeks yet in order to get a more effective picture. However, every woman is different and many larger women have reported being able to use an abdominal ultrasound at about that time too. Each case will be different and has to be decided at the time, but be aware that transvaginal ultrasounds may have to be used just a bit longer in larger women.
4D GYN |
CCA Intima |
3D,4D Liver |
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3D Female fets |
3D Fetal face |
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4 D Bladder |
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3D 4D Bladder |
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3S 4D Obs |
3D 26 week fetal heart |
4D Fetal feet and toes |
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3D Fetal spain |
3D Stimulated Ovary |
4D Image of 25 week fetus in Cube |
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3D ultrasound is a medical ultrasound technique, often used during pregnancy, providing three dimensional images of the fetus. Often these images are captured rapidly and animated to produce a "4D ultrasound".
There are several different scanning modes in medical and obstetric ultrasound. The standard common obstetric diagnostic mode is 2D scanning. In 3D fetal scanning, however, instead of the sound waves being sent straight down and reflected back, they are sent at different angles. The returning echoes are processed by a sophisticated computer program resulting in a reconstructed three dimensional volume image of fetus's surface or internal organs, in much the same way as a CT scan machine constructs a CT scan image from multiple x-rays. 3D ultrasounds allow one to see width, height and depth of images in much the same way as 3D movies but no movement is shown. 4D ultrasounds involve the addition of movement by stringing together frames of 3D ultrasounds in quick succession.
3D ultrasound was first developed by Olaf von Ramm and Stephen Smith at Duke University in 1987
Clinical use of this technology is an area of intense research activity especially in fetal anomaly scanningbut there are also popular uses that have been shown to improve fetal-maternal bonding. 4D baby scans are similar to 3D scans except that they show fetal movement as shown in the video clip.
If the system is used only in the Obstetrics Application, the ultrasound energy is limited by the manufacturer below FDA limits for obstetrical ultrasound, whether scanning 2, 3 or 4 dimensionally. (The FDA limit for obstetrical ultrasound is 94 mW/cm2.) While there has been no conclusive evidence for harmful effects of 3D/4D ultrasound on a developing fetus, there still remains controversy over its use in non-medical situations, and generally, the AIUM recommends that 3D ultrasounds should be undertaken with the understanding that a risk may exist.
What is 4D Ultrasound?
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Material
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Speed of Propagation
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bone
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4080 m/s
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blood
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1570 m/s
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tissue
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1540 m/s
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fat
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1450 m/s
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air
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330 m/s
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The portion of a sound that is returned from the boundary of a medium. (echo) The angle of incidence influences the reflected and refracted waves.
Frequencies for adult imaging - 2.0mHz to 3.0mHz.
Frequencies for pediatric imaging - 5.0mHz to 7.5mHz to 12mHz.
Effect of higher frequencies on penetration - the higher the frequency the less penetration, the lower the frequency the greater the penetration.
Recommended Book
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Obstetric Ultrasound is the use of ultrasound scans in pregnancy. Since its introduction in the late 1950’s ultrasonography has become a very useful diagnostic tool in Obstetrics.
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1. Diagnosis and confirmation of early pregnancy.
The gestational sac can be visualized as early as four and a half weeks of gestation and the Yolk sac at about five weeks. The embryo can be observed and measured by about five and a half weeks. Ultrasound can also very importantly confirm the site of the pregnancy is within the cavity of the uterus.
2. Vaginal bleeding in early pregnancy.
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diagnosed. In such cases, it is reasonable to repeat the ultrasound scan in 7-10 days to avoid any error. The timing of a positive pregnancy test may also be helpful in this regard to assess the possible dates of conception. A positive pregnancy test 3 weeks previously for example, would indicate a gestational age of at least 7 weeks. Such information would be useful against the interpretation of the scans.
In the presence of first trimester bleeding, ultrasonography is also indispensible in the early diagnosis of ectopic pregnancies and moral pregnancies.
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Fetal body measurements reflect the gestational age of the fetus. This is particularly true in early gestation. In patients with uncertain last menstrual periods, such measurements must be made as early as possible in pregnancy to arrive at a correct dating for the patient. See. In the latter part of pregnancy measuring body parameters will allow assessment of the size and growth of fetus and will greatly assist in the diagnosis and management of intrauterine growth retardation ( IUGR ).
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The gestational Sac (GS)
A structure that develops in the uterus early in pregnancy, enclosing the developing baby and amniotic fluid. In an ultrasound, the gestational sac should be visible by five weeks of pregnancy. Measurement of the gestational sac diameter (GS) should increase by about 1 mm per day in early pregnancy.
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The Crown-rump length (CRL)
This measurement can be made between 7 to 13 weeks and gives very accurate estimation of the gestational age. Dating with the CRL can be within 3-4 days of the last menstrual period. (An important point to note is that when the due date has been set by an accurately measured CRL, it should not be changed by a subsequent scan. For example, if another scan done 6 or 8 weeks later says that one should have a new due date which is further away, one should not normally change the date but should rather interpret the finding as that the baby is not growing at the expected rate.
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The Biparietal diameter (BPD)
The diameter between the 2 sides of the head. This is measured after 13 weeks. It increases from about 2.4 cm at 13 weeks to about 9.5 cm at term. Different babies of the same weight can have different head size, therefore dating in the later part of pregnancy is generally considered unreliable. (Chart and further comments) Dating using the BPD should be done as early as is feasible.
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The Femur length (FL)
Measures the longest bone in the body and reflects the longitudinal growth of the fetus. Its usefulness is similar to the BPD. It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. (Chart and further comments) Similar to the BPD, dating using the FL should be done as early as is feasible.
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The development of a baby is quite an intricate journey. From the moment that the egg and sperm meet, a baby is beginning the developmental process. This early part of development lays the foundation for a healthy pregnancy and the birth of a healthy baby. Unfortunately, because these early weeks involve such a complex process, things can go wrong and ultimately end in a pregnancy loss. If a possible complication in early pregnancy is suspected, your health care provider will use a combination of blood tests and ultrasound tests to make a clear diagnosis. A blood test can be used to monitor hCG levels and progesterone levels. Ultrasounds can be used to visually see what development is taking place in the uterus and to measure the progress.
It is common to have many questions about what this early development truly involves and what is to be expected. We have gathered information from different sources in order to provide the best guidelines of what normal early fetal development looks like. However, just as every woman is different, every pregnancy develops differently. This information should be used as a general guide for healthy pregnancy development, although development may vary due to the mother’s health or a miscalculation of ovulation. Gestational age is the age of the pregnancy from the last normal menstrual period (LMP), and fetal age is the actual age of the growing baby. Most references to pregnancy are usually in gestational age rather than fetal age development, but we have included both so that it is clear what stage development is at.
Week 1 & 2 Gestational Age - (Conception)
At this stage, the menstrual period has just ended and your body is getting ready for ovulation. For most women, ovulation takes place about 11 - 21 days from the first day of the last menstrual period. During intercourse, several hundred million sperm are released in the vagina. Sperm will travel through the cervix and into the fallopian tubes. When conception takes place, the sperm will penetrate an egg and create a single set of 46 chromosomes called a zygote - the basis for a new human being. The fertilized egg, called a morula, spends a couple of days traveling through the fallopian tube toward the uterus and dividing into cells (this dividing process is where many chromosomal abnormalities occur). The morula becomes a blastocyst and will eventually end up in the uterus. Anywhere from day 6 - 12 after conception, the blastocyst will imbed into the uterine lining and begin the embryonic stage.
Weeks 3-4 - Gestational Age (Fetal Age 2 weeks)
Development
The earliest change that can be seen through a vaginal ultrasound at this time will be the “decidual reaction” which is the thickening of the endometrium. The endometrium lining thickens as the blastocyst burrows into it. This cannot always be detected by ultrasound—sometimes it may take a special eye or very good equipment to see this “reaction” in the endometrium lining.
*A key fact to remember when using ultrasounds is that a transvaginal ultrasound can detect development in the uterus about a week earlier than a transabdominal ultrasound.
Hormones
hCG: Once implantation occurs, the pregnancy hormone Human Chorionic Gonadotropin (hCG) will develop and begin to rise. This hormone will signal that you are pregnant on a pregnancy test. hCG can be detected through two different types of blood tests or through a urine test. A quantitative blood test measures the exact amount of hCG in the blood, and a qualitative hCG blood test gives a simple yes or no answer to whether you are pregnant or not.
Doctors will often use the quantitative test if they are closely monitoring the development of a pregnancy. After implantation occurs, the hormone will begin to rise and should increase every 48-72 hours for the next several weeks.
Progesterone: The follicle from which the egg was released is called the corpus luteum. It will release progesterone that helps thicken and prepare the uterine lining for implantation. The corpus luteum will produce progesterone for about 12-16 days (the luteal phase of your cycle.) When the egg is fertilized, the corpus luteum will continue to produce progesterone for the developing pregnancy until the placenta takes over around week 10. Progesterone is the hormone that helps maintain the pregnancy until birth. Sometimes, the failure of the corpus luteum to adequately support the pregnancy with progesterone can result in an early pregnancy loss. Progesterone inhibits immune responses, decreases prostaglandins, and prevents the onset of uterine contractions.
Week 5 - Gestational Age (Fetal age 3 weeks)
Development
The gestational sac is often the first thing that most transvaginal ultrasounds can detect at about 5 weeks. This is seen before a recognizable embryo can be seen. Within this week, at about week 5 ½ to the beginning of the 6th week, a yolk sac can be seen inside the gestational sac. The yolk sac will be the earliest source of nutrients for the developing fetus.
Hormones
Human chorionic gonadotropin (hCG) levels can have quite a bit of variance at this point. Anything from 18 - 7,340 mIU/ml is considered normal at 5 weeks. Once the levels have reached at least 2000, some type of development is expected to be seen in the uterus using high resolution vaginal ultrasound. If using a transabdominal ultrasound, some type of development should be seen when the hCG level has reached 3600 mIU/ml. Although development may be seen earlier, these levels provide a guide of when something is expected to be seen.
Progesterone levels also can have quite a variance at this stage of pregnancy. They can range from 9-47ng/ml in the first trimester, with an average of 12-20ng/ml in the first 5-6 weeks of pregnancy.
With both hCG levels and progesterone levels, it is not the single value that can predict a healthy pregnancy outcome. It is more important to evaluate two different values to see if the numbers are increasing. Levels of hCG should be increasing by at least 60 % every 2-3 days, but ideally doubling every 48-72 hours. Progesterone levels rise much differently than hCG levels, with an average of 1-3ng/ml every couple days until they reach their peak for that trimester. In situations when there is a concern of an ectopic pregnancy or miscarriage, hCG levels will often start out normal, but will not show a significant increase or will stop rising all together, and progesterone levels will be low from the beginning.
Week 6 - Gestational Age (Fetal age 4 weeks)
5 ½ to 6 ½ weeks is usually a very good time to detect either a fetal pole or even a fetal heart beat by vaginal ultrasound. The fetal pole is the first visible sign of a developing embryo. This pole structure actually has some curve to it with the embryo’s head at one end and what looks like a tail at the other end. The fetal pole now allows for crown to rump measurements (CRL) to be taken, so that pregnancy dating can be a bit more accurate. The fetal pole may be seen at a crown-rump length (CRL) of 2-4mm, and the heartbeat may be seen as a regular flutter when the CRL has reached 5mm.
If a vaginal ultrasound is done and no fetal pole or cardiac activity is seen, another ultrasound scan should be done in 3-7 days. Due to the fact that pregnancy dating can be wrong, it would be much too early at this point to make a clear diagnosis on the outcome of the pregnancy.
Week 7 - Gestational Age (Fetal Age 5 weeks)
The hCG levels will peak at about 8-12 weeks of pregnancy and then will decline, remaining at lower levels throughout the remainder of the pregnancy. If the levels are questionable, an ultrasound scan should be used to diagnose the pregnancy outcome. Ultrasound findings are much more accurate at diagnosing pregnancy viability after 5-6 weeks gestation than hCG levels are.
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An ultrasound is done in most pregnancies around the mid part of a pregnancy. This is sonographical study is known as the fetal anatomy survey or the fetal anomaly screen. It is recommended to do a scan on 18-22 weeks of pregnanancy.
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The way this scan is done is that woman will have a full bladder before the start of the exam. Sonologist will do ultrasound . woman pregnant belly will have a special gel placed on it to help enhance the picture from the sound waves of the ultrasound. you, or in some cases the physician, will use the ultrasound transducer wand and move it over her abdomen.
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An ultrasound is done in most pregnancies around the mid part of a pregnancy. This is sonographical study is known as the fetal anatomy survey or the fetal anomaly screen. It is recommended to do a scan on 18-22 weeks of pregnanancy. The way this scan is done is that woman will have a full bladder before the start of the exam. Sonologist will do ultrasound . woman pregnant belly will have a special gel placed on it to help enhance the picture from the sound waves of the ultrasound. you, or in some cases the physician, will use the ultrasound transducer wand and move it over her abdomen.
Ultrasonologist determine things about baby and pregnancy. You need to look on the size of baby in comparison to others babies of the same gestational age or they may look at placenta.
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We often talk about how the first thing we'll do after our baby is born is to count fingers and toes. Now ultrasound technology can enable use to count fingers and toes prior to birth. Though being able to count each finger and toe can depend on how cooperative baby is being during the ultrasound exam.
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It is more likely that sonologistwill be able to see bigger areas like baby's limbs - arms and legs. Ultrasound technician will measure baby's thigh bone (femur), the tibia and fibula. These will also help calculate how well baby is growing for his or her gestational age.In addition to look at the legs, Sonologist should also measure parts of baby's arms. The bones of the arms (radius, ulna) are measured when possible.
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| BPD The diameter between the 2 sides of the head. This is measured after 13 weeks. It increases from about 2.4 cm at 13 weeks to about 9.5 cm at term. Different babies of the same weight can have different head size, therefore dating in the later part of pregnancy is generally considered unreliable. (Chart and further comments) Dating using the BPD should be done as early as is feasible.
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BPD |
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The single most important measurement to make in late pregnancy. It reflects more of fetal size and weight rather than age. Serial measurements are useful in monitoring growth of the fetus. (Chart and further comments) AC measurements should not be used for dating a fetus.
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Abdominal Circumference
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The Femur length Measures the longest bone in the body and reflects the longitudinal growth of the fetus. Its usefulness is similar to the BPD. It increases from about 1.5 cm at 14 weeks to about 7.8 cm at term. (Chart and further comments) Similar to the BPD, dating using the FL should be done as early as is feasible.
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Ultrasonography has become indispensible in the localization of the site of the placenta and determining its lower edges, thus making a diagnosis or an exclusion of placenta previa. Other placental abnormalities in conditions such as diabetes, fetal hydrops, Rh isoimmunization and severe intrauterine growth retardation can also be assessed. |
Placenta |
Transvaginal Scan With specially designed probes, ultrasound scanning can be done with the probe placed in the vagina of the patient. This method usually provides better images (and therefore more information) in patients who are obese and/ or in the early stages of pregnancy. The better images are the result of the scanhead's closer proximity to the uterus and the higher frequency used in the transducer array resulting in higher resolving power. Fetal cardiac pulsation can be clearly observed as early as 6 weeks of gestation.
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TVS Scan 6 week |
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The sex of the baby can usually be determined by ultrasound at any time after 16 weeks, often at the dating scan around 20 weeks into the pregnancy depending upon the quality of the sonographic machine and skill of the operator. This is also the best time to have an ultrasound done as most infants are the same size at this stage of development. Depending on the skill of the sonographer, ultrasound may suffer from a high rate of false negatives and false positives. This means care has to be taken in interpreting the accuracy of the scan. |
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