by Elizabeth MacDonald
This post made possible by the generous support of My Baby’s Heartbeat Bear
This article originally published on mybabysheartbeatbear.com on November 10, 2015.
There is something so exciting about seeing your little jelly bean bouncing around on the ultrasound screen! Counting down the days until you can watch your baby swim around is something almost all couples do.You get pictures and possibly a video with the heartbeat. All of it just solidifies that you truly are carrying a little life inside.
Healthy, low-risk pregnant women are recommended to only receive a sonogram at 20 weeks, but there are times when other scans are needed to check on the baby. There are six common sonograms performed throughout pregnancies, and one or more may be recommended to you. I’m going to break them down and explain their individual purposes and what you can expect to leave knowing after having one.
Before describing the sonograms in the next article, in this first article we’re going to talk about the difference between a sonogram and an ultrasound and explain the most common sonograms utilized in prenatal care. A sonogram is the image generated during ultrasonography, which is a diagnostic imaging technique that uses ultrasound to visualize anything inside the body. Ultrasound is a sound frequency above the range audible to humans, which is about 20 kHz. Both terms are used interchangeably by most people, but in layman’s terms an ultrasound is using sound waves to see or hear something inside the body. A sonogram is the actual visual picture of what the ultrasound is picking up. There are seven types of ultrasounds that may be performed during pregnancy:
Standard Ultrasound – Traditional ultrasound exam which uses a transducer over the abdomen to generate 2-D images of the developing fetus .
Advanced Ultrasound – This exam is similar to the standard ultrasound, but the exam targets a suspected problem and uses more sophisticated equipment.
Doppler Ultrasound – This imaging procedure measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells.
3-D Ultrasound – Uses specially designed probes and software to generate 3-D images of the developing fetus.
4-D or Dynamic 3-D Ultrasound – Uses specially designed scanners to look at the face and movements of the baby prior to delivery.
Fetal Echocardiography – Uses ultrasound waves to assess the baby’s heart anatomy and function. This is used to help assess suspected congenital heart defects.
Your doctor or midwife will likely use the Doppler during each prenatal visit to pick up the baby’s heartbeat. Generally, they keep it short and use this as reassurance to you that your baby is doing well. This is very common, but can be denied if you feel the urge not to have it done. (As an almost fourth time mom here, I’ll tell you just how amazing it is to hear that little heartbeat every few weeks!)
While many women will receive other ultrasounds during their pregnancy, other than the Doppler to check heart tone at prenatal exams, the standard ultrasound anatomy scan around 20 weeks is the most common. See below for more information about the anatomy scan.
- Anatomy Scan: Between 18-21 weeks, you will have a more in-depth ultrasound done to determine the baby’s size, weight, and to measure growth ensuring the fetus is developing according to plan. In addition, the anatomic ultrasound looks at and takes measurements of many different anatomic parts of the fetus. The technician or the doctor will be looking for any signs of slower than normal development. The skeleton should be hardening at this point and the sex of the baby may be visible. In many cases, the baby may have its legs crossed or be facing away from the abdomen and thus the sexual organs will not be visible during the anatomic ultrasound. But fingers crossed, you will learn the gender! On the plus side, you’ll receive many pictures of your little one during this scan. The following fetal parts are checked during the anatomy ultrasound:
- Face: Depending on the positioning of your baby, the technician may or may not be able to detect if your baby has a cleft lip. Rarely are they able to detect if there is a cleft of the palate.
- Brain: The technician will be assessing the fluid-filled spaces inside the brain and the shape of the cerebellum, which is in the back of the brain. He or she will also be able to identify if any cysts are in the choroid plexus, which is a tissue in the brain that produces cerebrospinal fluid. Fetal cysts may indicate an increased risk for a chromosome abnormality; however, the majority of these cysts disappear by the 28th week of pregnancy with no effect on the baby.
- Skull (shape, integrity, BPD and HC measurements)
- Neck (nuchal fold thickness)
- Spine: Your baby’s spine will be evaluated in the long view and in a cross section. The technician will be looking to make sure that the vertebrae are in alignment and that the skin covers the spine at the back.
- Heart (rate, rhythm, 4-chamber views, outflow tract): Congenital Heart Defects are one of the leading causes of birth defects and infant death. A prenatal diagnosis can prepare you and your medical team to provide your infant with the best medical care possible throughout your pregnancy and after birth.
- Thorax (shape, lungs, diaphragm)
- Abdomen (stomach, kidneys, liver, bladder, wall, umbilicus, cord, abdominal circumference AC)
- Limbs (femur, tibia, fibia, humerus, radius, ulna, hands, feet, femur length FL)
- Genitals (gender, abnormality)
- Cervix (length and opening)
Based upon the results of the measurements, the gestational age of the baby will be predicted based upon the average size of other babies scanned during the 20th week of pregnancy. If any abnormalities are found, additional examinations are indicated.
In our next article, we’ll go more in depth into the other Sonograms some women experience in pregnancy and their purpose. No matter what kind of scan you’re given, it can be an exciting time and a bit of an emotional roller coaster. Hearing and seeing how your baby is doing can be both nerve-wrecking and encouraging. Read here for more potential emotional impact of a prenatal ultrasound experience.