Ultrasounds (also called sonograms or sonos or scans)

Ultrasound has been available for many years. Its safety in pregnancy has been studied extensively. To date there are no documented fetal side effects from ultrasound. However, as with all biological tests, it is impossible to guarantee its absolute safety.

Routine ultrasounds

Every patient is scheduled for a minimum of 3-4 routineultrasounds during the pregnancy.

a) The first is about 7-8 weeks gestation, and we call it the “check viability” ultrasound. This is to make sure that the pregnancy is normal and healthy (or viable), to establish the due date accurately, and to see how many babies there are. For normal conception, there is a 1% chance of twins!

b) The second ultrasound is about 18-20 weeks gestational age. It is designed to assess the growth, development and anatomy of the baby, looking for possible major birth defects. Any abnormal findings will be carefully followed up on.We call this the "head to toes anatomy scan."

c) The third routine ultrasound is at about 30-34 weeks, ideally at week 32. This ultrasound helps in managing the third trimester. We check the size and position of the baby, look at the placenta and the amniotic fluid, and measure the Doppler flow (discussed below).

d) The fourth routine ultrasound is done around the due date (if you are still pregnant by then!).

Additional Ultrasounds

At any time during your pregnancy an ultrasound can be done for specific indications or to help manage high-risk pregnancies. Reasons for non-routine ultrasound include vaginal spotting or bleeding, maternal conditions such as high blood pressure or diabetes, concern for the baby's size or position, to check the level of amniotic fluid, and other reasons as well.

Doppler Ultrasound

Doppler ultrasound is used to examine blood flow through vessels located in the umbilical cord, the placenta and/or the baby's heart and brain. We do a Doppler flow study with every 32-week ultrasound. This measures the resistance to flow. A higher resistance means that the baby’s heart is working harder to pump its blood, a possible early sign of a baby that may not be receiving enough blood flow from the placenta.

“Detailed” Ultrasound

A “detailed” ultrasound is sometimes called a "genetic ultrasound". It includes a highly detailed evaluation of fetal anatomy. Special concerns are the inspection of the fetal brain, heart, spine, renal (kidney) system, gastrointestinal system, skeletal system, and craniofacial anatomy. This type of ultrasound is generally reserved for patients who have previously had babies with birth defects, patients "at risk" for babies with birth defects, those undergoing amniocentesis, as a follow-up if a routine ultrasound detected a possible problem or patients with other pregnancy risk factors that might affect fetal well being.
We refer patients to a specialist for this type of exam as needed.

Cervical Length (CL) Ultrasound

This test is becoming a very important addition to obstetrical care. Many experts now advocate that a vaginal ultrasound for cervical length be a routine procedure at least once per pregnancy (usually 18-20 weeks), and more often in high-risk patients such as multiple gestation, incompetent cervix, or those with a history of preterm labor, premature birth, abnormal uterine anatomy or surgery on their cervix (LEEP or cone biopsy).

Patients at high risk for premature birth such as twins or moms who have previously given birth early might have a CL scan every 2 weeks from 16 to 24 weeks or beyond.

Fetal Echocardiography

Fetal echocardiography is a type of specialized ultrasound. This means that the ultrasound and/or Doppler are used to carefully inspect the fetal heart. Abnormalities in the heart's structure (the chambers) and the heart's function can be detected. Not all are serious, and many resolve spontaneously either during pregnancy or after delivery. Some are serious, however, and may require further evaluation and treatment.
We refer patients to a specialist for this type of exam as needed.

3-D (Three-Dimensional) Ultrasound

Using 3-D (and even 4-D) technology, it is possible to obtain a detailed three-dimensional ultrasound image. With the use of surface rendering techniques, one can actually “see” body parts such as the face, limbs, etc. almost like looking at a sculpture. Although not a standard ultrasound, there may be situations where a valid medical indication suggests a need to perform a 3-D scan. Some people arrange to have one just to be able to “see” their baby before it is born.

3-D and 4-D Ultrasounds are available here in the office. We have advanced ultrasound machines that provides startlingly life-like views of the fetal face and body. Please ask the front desk about our 3D/4D package!

Limitations of Ultrasound

It is important to be aware of the limitations of ultrasound. At the minimum, proper detection of abnormalities requires good equipment, a well-trained ultrasonographic technologist or doctor and a detectable abnormality. Not all abnormalities are detectable. Sometimes the abnormality shows up later in pregnancy and is not detectable sooner. Sometimes the abnormality is so small that it is not “seen” during the exam (small holes in the heart). Sometimes the position of the baby, the placenta and the amniotic fluid are such that the abnormality is obscured. Rarely a small spinal cord abnormality called a meningomyelocele can be missed if it is low in the spine and the backside of the baby is pressed against the uterine wall. Sometimes babies are born with visible abnormalities that are not looked for during ultrasound (such as how many fingers per hand).

Some abnormalities present at birth are not detectable during routine ultrasound (such as newborn hearing deficits). We do our best to detect what is there to be detected, but there is still the remote possibility that our ultrasound may fail to detect a condition that is then discovered after the baby is born.