A monthly newsletter from the office of Dr Mary Kirk
July 2016

3D Ultrasound at 30 Weeks


Today, ultrasound is utilized in nearly every area of medicine. It is relatively inexpensive to perform compared to other imaging methods and does not expose patients to radiation. Although most people immediately think of babies in relation to ultrasound procedures, only a very small portion of Sonographers ever scan pregnant women. There are currently six types of credentials for Sonographers in the United States and a number of subcategories to specialize in. Our office specializes in Obstetrics and Gynecology, so our ultrasound exams relate specifically to these areas. Below, we will discuss ultrasound for pregnancies, both the diagnostic and elective exams we offer at our office.

Typically, the first ultrasound of a pregnancy is performed between 7 and 11 weeks. Babies grow cell by cell, so it takes time for anything to be visible by ultrasound examination. However, sometimes one will be performed slightly earlier or later depending on the patient's situation and medical history. This ultrasound is the most accurate estimation of exactly how far along a pregnancy is. Regardless of how quickly baby grows, the dating will not change. The ultrasound measurement gives the true age of baby, accurate to within 3-5 days during the first trimester. Also, the structure of the sac that the baby is growing in, multiples like twins and triplets (what type of multiples they are), the condition of the uterus in response to the pregnancy, and the ovaries are evaluated.

If all appears as expected during the first trimester, the second ultrasound will be performed at 20 weeks of gestation. At this point, baby has all of its organs/parts and is now large enough to evaluate in great detail. An inventory is taken of baby's anatomy, and the texture, size, and position of important structures is evaluated for any signs of irregularity. Certain measurements and features can be used to detect the likelihood of genetic abnormalities and growth problems. This ultrasound also evaluates the fluid surrounding the baby, the placenta, the mother's cervix, and the umbilical cord. These findings will determine whether more in-depth imaging needs to be performed.
If all is well, the next routine ultrasound is performed around 36 weeks. This evaluates the fluid around baby, the appearance of the placenta, baby's position, and how quickly baby has grown. Baby's size at term can be estimated at this point. Depending on the findings during these ultrasounds and the mother's medical history or health during the pregnancy, further ultrasounds may be warranted.
Diagnostic ultrasounds are medical evaluations and are not intended for the purpose of entertainment. This is one of several reasons why there is a limit to the number of guests a patient may bring. The Sonographer not only has a lot to focus on without the distraction of too many people, but your Doctor may need to speak to you about sensitive information that may be obtained through the exams. 

Some may wonder why ultrasounds are not performed during every visit, either for their enjoyment or for peace of mind purposes. There are several reasons. First, all imaging professionals are mindful of what is called the ALARA principle. ALARA stands for "As Low As Reasonably Achievable". This means that all effort will be put forth to ensure that imaging "power" levels are kept as low as diagnostic quality will allow and that purposeless exposure does not occur during medical evaluations. This principle was originally created as a regulation of radiation exposure. Although ultrasound is usually employed as a first response imaging tool due to its safety record and ultrasound utilized beyond even diagnostic levels is not currently known to have negative effects on humans, the ALARA principle is still utilized as a precaution. Looking at baby during every visit of the pregnancy does not provide us with any new beneficial information unless there are specific problems that require close monitoring.

Ultrasounds are captivating with their ability to give a glimpse of a child in the womb. Families are also anxious to know whether they will be welcoming a son or daughter (sometimes both!). Our office has started offering elective ultrasounds. These ultrasounds are intended for the enjoyment  of the patient and guests, and are scheduled separately from any medical appointment. These may be scheduled at least 1 week apart from other elective and/or diagnostic scans. 

Baby's Foot - Regular Ultrasound vs 3D Ultrasound

Parents who cannot wait for their anatomy scan at 20 weeks may choose to schedule a nondiagnostic ultrasound as early as 16 weeks for the purpose of discovering gender. Although the baby begins developing genitalia at approximately 11 weeks of gestation, it does not become well enough defined for ideal determination until around 16 weeks. Baby boys and girls can appear very similar up until then. The male genitalia is not well developed and the female genitalia may be swollen or protrude. Babies also grow a lot in that month! Things are just too tiny for sure detail before 16 weeks. Other considerations for the limitations of gender determination include the position of the baby and the mother's body tissue content. 

A 3D/4D ultrasound is not usually performed until after 27 or 28 weeks of pregnancy. Babies are very skeletal in appearance until then and are too tiny to image well. 3D imaging is very different than 2D imaging. Unlike 2D imaging, only one angle can be used to image any particular feature optimally. The baby must be facing the camera and there needs to be plenty of fluid between the baby's face and mommas belly to get that beautiful picture! When captured, however, the images are truly amazing! These glimpses into the baby's world can be wondrous for the parents and their families! 

Mommas-to-be should take care to be extra hydrated prior to receiving any ultrasound. A higher water content in her body tissues and increased amniotic fluid levels aid in obtaining the best pictures possible. It's healthy for her too! 

3 people plus the patient are allowed in the room for all exams. For elective exams, patients will receive a disk with pictures that are captured of baby. We also love helping out with gender reveal parties. We will conceal the ultrasound results in an envelope for those who want to wait to find out! Although we almost always are successful, occasionally we are unable to determine gender due to baby's position. It's best to keep this in mind when planning your big event!

If you're interested in ultrasound services for yourself or as a gift, please contact our office and we will be more than happy to talk with you about options.

Fun Fact:

Ultrasound images are created by aiming sound waves - above the audible range of human hearing - at various body structures or tissues, and detecting the echoes that bounce back.

The first medical  ultrasounds were developed from equipment used to detect structural flaws in ships and, in the beginning, could only get a picture of the head. 

Dr Mary C Kirk | 918-508-2200 | www.kirkobgyn.com