Ultrasound

 If you have ever been pregnant you have probably had at least one ultrasound because currently about 65% of the woman who are pregnant have an ultrasound. But just because you have had an ultrasound doesn't mean that you understand what one is, how they work, what kinds there are or even the many reasons why an ultrasound might be done.

An ultrasound is a medical procedure that uses sound waves to show a picture of a baby in the uterus. The reason for this is that the ultrasound uses sound waves instead of radiation to form the pictures. And because of the fact that it uses sound waves rather than radiation this makes the procedure much safer for pregnant women. One of the main reasons that ultrasounds are done is to provide important information about the health and condition of both the fetus and the uterus. With this information the doctor can plan what they are going to do when it comes to providing for the pregnant woman and her unborn baby, which helps to improve the outcome of the pregnancy. What this means is that when using an ultrasound there is a smaller chance of complications happening from lack of information.

An ultrasound works by bouncing sound waves off of the developing fetus. These sound waves produce echoes which are then analyzed by the computer to produce a moving picture or even a still picture on a screen. This is what is called a sonogram, which is one of the reasons that the ultrasound technique is also called sonography. The two terms ultrasound and sonogram are used interchangeably, they are still technically very different from one another. The one thing that you need to know about ultrasounds is that although there are several different kinds of ultrasounds, there are basically seven different types, the principle of the ultrasounds are the same.

 Here is a look at the seven different types of ultrasounds:

1. Transvaginal scans - these are specially designed probes that are placed either inside the vagina or on the outside of the vagina to help generate sonogram images. This type of ultrasound is used during the early stages of pregnancy when the uterus is closer to the vagina rather than the abdomen walls.
   
2. Standard ultrasound - this is the main style of ultrasound that is used in pregnant women. This style of ultrasound uses a transducer over the abdomen to generate 2D images of the developing fetus.
   
3. Advanced ultrasound - this one is very similar to the standard ultrasound but the main exception is that it targets a suspected problem and uses a lot more sophisticated equipment.
   
4. Doppler ultrasound - is an imaging procedure that measures the slight change in the frequency of the ultrasound waves as the bounce off of moving objects such as blood cells. It is this type of ultrasound that is used to look at the blood flow during high risk pregnancies.
   
5. 3D Ultrasound - has specially designed probes and software that generates a 3D image of the developing fetus.
   
6. 4D or Dynamic 3D Ultrasound - this style of ultrasound uses specially designed scanners that look at the face and the movements of the baby right before delivery.
   
7. Fetal Echocardiography - uses the ultrasound waves to look at and assess the baby's heart anatomy and its function. This type of ultrasound is used to help assess suspected congenital heart defects in fetuses.

Because of the fact that ultrasounds are actually diagnostic procedures that are used to detect or help aid in the detection of abnormalities and conditions that are related directly to the pregnancy there is no set number of ultrasounds that may be done. In fact many times an ultrasound is used in combination with other tests to help validate a certain diagnosis. Something else to keep in mind is that there is no set time to have an ultrasound, this is going to depend on your doctor and your how your pregnancy is playing out, but during the 16th and 20th week of your pregnancy is the most common time to have an ultrasound. Here is a breakdown of what the ultrasounds are looking for during the different trimesters:

First Trimester:

• Confirm that you are actually pregnant
  
• Confirm that the fetus has a heartbeat, depending on how soon you go in the heartbeat might be able to be heard without an ultrasound
  
• Measure the crown to rump length which will give you the gestational age of the fetus
  
• Confirm molar or ectopic pregnancies
  
• Assess abnormal gestation
  

Second Trimester:

• Find and diagnosis any fetal malformation
  
• Week 13-14 characteristics of Down syndrome can appear
  
• Weeks 18-20 you need to look for congenital malformations
  
• Look for structural abnormalities
  
• Can confirm multiple pregnancy if it hasn't already been done
  
• Double check dates and the growth of the fetus
  
• If needed can confirm intrauterine death
  
• Can identify too much or too little amniotic fluid, also called hydramnios or oligohydramnios
  
• Evaluate the well being of the fetus in general
  

Third Trimester

• Look for and identify the placental location
  
• If needed can confirm intrauterine death
  
• Observe fetal presentation
  
• Observe fetal movements
  
• Identify uterine and pelvic abnormalities of the mother
  

 Although in most cases ultrasounds are done for no particular medical reason, that isn't always the case. Ultrasounds are also used to help identify specific conditions, meaning there is a medical reason that they are done. The conditions that an ultrasound is used to identify are:

1. Suspected ectopic pregnancy - in some women when they get pregnant rather than carrying the baby in the uterus the fetus might be located in a fallopian tube or even in the uterus. An ultrasound is used to help diagnose where the fetus is being carried.
   
2. Possible miscarriage - some women have bleeding early in the pregnancy, which can signal a miscarriage, but there can also be no heartbeat or no signs of fetal movement as a sign of miscarriage. The ultrasound is done to determine if the fetus has died and to see if the woman will miscarry.
   
3. Multiple fetuses - some woman have a higher chance of carrying multiple fetuses, especially women who are infertility drugs. An ultrasound is done to detect the presence of more than one baby.
   
4. Age of the fetus - if a woman is not sure of when her last menstrual period was or when she had sexual intercourse there is no accurate way to tell how old the fetus is. In these cases an ultrasound can be done to find out the size of the fetus which can help determine the due date of the baby. Keep in mind that this procedure is more accurate in the first half of the pregnancy.
   
5. Various birth defects - they can help spot certain birth defects such as spina bifida. If the ultrasound shows that there is an abnormality they woman can be referred to a medical center that can do more in depth ultrasounds so the problem can be discovered and the options can be discussed.
   
6. Screening for Down Syndrome - it used to be that the best way to screen for Down syndrome was the blood test in the second trimester. But now you can use first trimester ultrasounds and blood work to screen for Down syndrome and other chromosomal birth defects.
   
7. Fetal growth - this can help the doctor determine if the fetus is growing too quickly or even too slowly. And by discovering this the doctor can determine if it is the fetus that has the growth problem or if it is too much or too little amniotic fluid.
   
8. Cause of second and third trimester bleeding - this type of bleeding is normally caused by placental problems but by using an ultrasound to determine what is causing the bleeding the doctor can determine if a cesarean delivery is required or if any special care is going to be needed.
   
9. Fetal well being late in pregnancy - this is done to monitor the health of the fetus in the later trimesters for women who are at a higher risk in their pregnancy, in fact it can also be done sooner in patients who are at a very high risk. This can actually benefit the baby if they baby will benefit from being delivered early.
   
10. Guiding other tests - this can help doctors make the decision about doing certain other tests. Some other tests that can be guided by an ultrasound are amniocentesis and chorionic villus sampling.
    
11. Determining fetal position around time of delivery - in some cases babies do not change their position right before they are born, they actually remain breech or in other positions. This can cause numerous complications and lead to an emergency cesarean delivery. But an ultrasound can detect which way the baby is facing right around the time of the delivery.