When the pregnancy hits the 20th week of gestation, an anatomic ultrasound is often ordered. The ultrasound will be used to determine fetal anomalies, the baby's size, weight and to measure growth ensuring the fetus is developing according to plan.
Anatomic Ultrasound in Pregnancy
By the 20th week of pregnancy, the baby can weigh up to 11 ounces and measure 10 inches outstretched. The fetus has fingerprints, tiny arms and legs and the genitalia are often formed. The pregnant woman is beginning to “show” with a small baby bump popping out in the front of her abdomen. The rate of growth from the 20th week until the 40th week will increase exponentially.
When a pregnant woman hits the 19th-20th week of gestation, an anatomic ultrasound is often ordered. The ultrasound at this time is the most extensive ultrasound done and often will be used to determine the babies size, weight and to measure growth ensuring the fetus is developing according to plan. In addition, the anamtomic ultrasound looks at and takes measurements of amny different anatomic parts of the fetus.
Before the Ultrasound
Before the ultrasound can be performed, mom will often need to drink plenty of water. The bladder should be relatively full when the technician performs the anatomic ultrasound in order to making the ultrasound results more clear.
What Will the Technician Be Looking For
During the 20th week anatomic ultrasound, 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 their legs crossed or be facing away from the abdomen and thus the sexual organs will not be visible during the anatomic ultrasound.
What Will Happen During the Ultrasound?
After the pregnant woman is called into the ultrasound room, she will be asked to lie flat on an ultrasound table. Her full bladder may pose a bit of discomfort, but otherwise the ultrasound will be painless and enjoyable. The technician or doctor will apply a warmed gel to the abdomen and using a small paddle, scan the abdomen taking a look at baby in the uterus. The following fetal parts are checked during the anatomy ultrasound:
- Brain (ventricles, choroid plexus, mid-brain, posterior fossa, cerebellum, cisterna magna, measurements of anterior and posterior horns of lateral ventricles)
- Skull (shape, integrity, BPD and HC measurements)
- Neck (nuchal fold thickness)
- Heart (rate, rhythm, 4-chamber views, outflow tract)
- 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.
Pictures and Fun!
Many ultrasound technicians will print off various pictures of the face and occasionally the sexual organs for mom and dad to enjoy. These pictures will vary based upon whether the scan completed is a 2D, 3D or 4D scan. More advanced ultrasounds can render a 3 dimensional picture of baby for mom and dad to enjoy.
Some anatomic ultrasounds will be performed on machines with video recording capabilities. If you wish to have a video recording of the ultrasound, make sure to ask the technician before beginning if that is a possibility.
The anatomic ultrasound performed in the 20th week of gestation is a time of pride, joy and anxiety. Some parents are looking to have a boy or a girl while others are simply happy to put a face to the movement inside their belly.