A hip ultrasound is a safe and painless test that uses sound waves to make images
of the hip.
During the examination, an ultrasound machine sends sound waves into the hip area,
and images are recorded on a computer. The black-and-white images show the internal
structures of the hip, including the ball-shaped top of the thighbone (femoral head)
and its socket (acetabulum) in the pelvic bone.
It can be performed on babies up to about 6 months of age.
In a normal-functioning hip, the femoral head rests comfortably in its socket.
In babies with DDH, the femoral head moves back and forth within the socket; in more
serious cases, it may move out of the socket, but can be put back into place with
pressure — this is called dislocation. In the most severe cases, it may not
be possible to put the femoral head into the socket at all.
The likelihood of DDH increases in these situations:
pregnancies in which the fetus is cramped in the uterus (due to a decrease in
the amount of amniotic fluid, called oligohydramnios)
abnormal position of the baby in the womb (breech position)
babies with a family history of DDH
Also, DDH occurs more frequently in girls than boys and among first-born infants.
Doctors will consider all of these factors when deciding whether a baby's hips
should be checked by ultrasound. In addition, a baby will be sent for ultrasound if
the doctor finds an abnormality of the hip during a physical examination, such as:
at birth, an inability to move the thigh outward at the hip as far as normally
a hip "click" heard or felt by the doctor when moving the infant's thigh outward
during a routine checkup
differences in the lengths or appearances of the infant's legs
Usually, you don't have to do anything special to prepare your baby for a hip ultrasound.
You should tell the technician about any medications your baby is taking before the
The hip ultrasound usually will be done in the radiology department of a hospital
or in a radiology center. Parents usually can accompany their child to provide reassurance
You'll be asked to partly undress your baby and to remove the diaper for the test.
Your baby will be placed on a table on his or her back or side. The room is usually
dark so the images can be seen clearly on the computer screen.
A technician (sonographer) trained in ultrasound imaging will spread a clear gel
on the skin of the hip. This gel helps with the transmission of the sound waves. The
technician will then move a small wand (transducer) over the gel. The transducer emits
high-frequency sound waves and a computer measures how the sound waves bounce back
from the body. The computer changes those sound waves into images to be analyzed.
Sometimes a doctor will come in at the end of the test to meet your baby and take
a few more pictures. The procedure usually takes about 20 minutes. Both hips are usually
examined for comparison.
What to Expect
The hip ultrasound is painless. Your baby may feel a slight pressure on the hip
as the transducer is moved, and the gel may feel wet or cold.
Babies might cry in the ultrasound room, especially if they're restrained, but
this won't interfere with the procedure.
Getting the Results
A radiologist (a doctor who is specially trained in reading and interpreting X-ray
and ultrasound images) will interpret the ultrasound results and then give the information
to your doctor, who will go over the results with you.
Results are usually ready in 1-2 days. In most cases, results can't be given directly
to the family at the time of the test.
No risks are associated with a hip ultrasound. Unlike X-rays, radiation isn't involved
with this test.
Helping Your Infant
It might be helpful to feed your baby just before the ultrasound to make him or
her more relaxed. If you're present during the test, comfort your baby with a calm
and soothing voice or sing a favorite song. Make sure to stand where he or she can
see your face.
If You Have Questions
If you have questions about the hip ultrasound, speak with your doctor. You can
also talk to the technician before the exam.