Obstetrical Ultrasound

Pregnancy Dating/Fetal viability

In the first trimester of pregnancy, women come for an ultrasound to determine their due date and to confirm that the pregnancy is alive and well and located within the uterus. Viability is demonstrated by documenting the fetal heart rate. The due date is determined by measuring the size of the embryo.

 

Evaluation for Ectopic Pregnancy

Occasionally, a pregnancy can start to develop in places other than the uterus. This is called an ectopic pregnancy. Women who have an ectopic pregnancy may have vaginal bleeding or pain in the early part of pregnancy. It is important to confirm that your pregnancy is in the right place if these symptoms occur. The only way to make sure that your pregnancy is growing in the uterus is with ultrasound.

 

Fetal nuchal translucency screen is performed between 10 and 14 weeks of gestation.

 

Nuchal Translucency Screen

Fetal nuchal translucency screen is performed between 10 and 14 weeks of gestation. It is a screening test for Down syndrome (also called trisomy 21), Edward syndrome (trisomy 18) and Patau syndrome (trisomy 13). These 3 conditions are all associated with developmental delay, and sometimes malformations in the newborn, therefore many parents want to know if these problems exist as early as possible. If your fetus is too big or too small, the test cannot be performed and will have to be rescheduled, so timing is very important. 

The test has two parts. First, an ultrasound is performed which may be across the abdomen or across the vagina, or both, depending on the position of the fetus. The fetus is measured to make sure it is the right size and examined with the ultrasound. We check to make sure everything looks like it is developing normally. As the fetus is only about 5-7 cm (the size of a large shelled peanut), not every problem can be seen. Dr. Minior will make sure there are 2 arms and two legs, 2 hands and 2 feet, and development of the face, brain, chest, and abdomen looks normal. The nuchal translucency, which is a fluid space in the back of the neck of the fetus, is then measured. A normal nuchal translucency is less than 3 mm. If an abnormality is detected, Dr. Minior will review this information and its implications with you. 

When the ultrasound part of the test is concluded, your blood will be drawn. The information from the ultrasound part of the test and the blood get sent to the lab, and after a week or so, a report will be faxed back to your referring doctor. The doctor will review the results with you in the office. The results are reported in the form of an odds that the fetus is affected with Down syndrome, such as 1:5 or 1:10,000. These odds can help you decide if you want to undergo any further testing in your pregnancy.

The nuchal translucency screen is about 98% sensitive to detect Down syndrome. This means that it picks up 98% of cases and misses 2%.  It is 95% sensitive to pick up trisomy 13 or 18. This test can now also tell you the gender of the fetus (this is 95% accurate). The added advantage of the nuchal screen is that it provides a very early assessment of the fetus for major defects in the body structure (anomalies or malformations), some of which may be lethal at birth.

Early Fetal Anatomic Survey

 

At 15-16 weeks gestation, the fetus is developed enough to see the majority of the parts of the body. If the parents desire, the fetus can be evaluated at this point to make sure it has normal anatomy. Early anatomy scan is also performed if there is an indication associated with an increased risk for abnormalities in the fetus such as advanced maternal age, an abnormal screening test, identical twins or a previous baby with a malformation.  Early anatomy scan is also suggested if there are conditions that make it difficult to see the fetus well, such as maternal obesity, fibroids, or a multiple gestation. At this test, many different body parts of the fetus are examined (see list below), the fetus is measured, and the position of the placenta and length of the cervix is evaluated. Transabdominal and transvaginal ultrasound is performed. 

Women that have an early anatomic survey should come back for a late anatomic survey (at 20-22 weeks) because some important parts of the body develop later (such as the corpus callosum in the brain) or are better evaluated after 20 weeks (such as the heart). After the scan, Dr. Minior will talk to you and discuss the results. If any abnormalities are detected, these will also be reviewed. Sometimes, it is not clear if there is a problem. In this case, Dr. Minior may ask you to return in 1 week. Occasionally, an abnormality is detected at 20-22 weeks that was not seen at the early anatomic survey because some anomalies develop later, the fetus is bigger or is in a better position to see that part of the body.

Parts of the fetal body that can be evaluated at 16 weeks include:

  • The face: nose and lips, profile (or side view of the face) and lenses of the eyes

  • The brain: the lateral ventricles, cerebrum, cerebellum, cisterna magna,
    choroid plexus, thalamus, falx cerebri

  • The heart and great blood vessels leaving the heart

  • The spine

  • The lungs and diaphragm

  • The stomach, bladder, kidneys, intestines, umbilical cord

  • The arms and legs, ankles, hands and feet, fingers and toes

  • Measurements of the fetus

  • The placenta and placental cord insertion

It is important to note that unfortunately, it is not possible to detect with ultrasound EVERY abnormality that can exist in a fetus. However, about 90-95% of abnormalities can be detected. 

ankle

feet

 

Late Fetal Anatomic Survey (also called Level II Ultrasound)

The late anatomic survey is performed between 20-22 weeks. This is the standard time to evaluate the anatomy of the fetus because it is easiest to see most of the body parts that have developed and there is still lots of fluid around the baby (which allows the doctor to see the parts of the body well). All of the same things that are evaluated at the early anatomy scan are examined again because the fetus is bigger, and it is easier to see if there are any problems. In addition, several important brain parts have now developed such as the corpus callosum and the cavum septum pellucidum, so these are also examined. The fetus is again measured and the uterine cervix and placental location are evaluated. Dr. Minior will talk to you after the scan and review the results. If there are any problems, these will be discussed and plans will be made for follow-up visits in pregnancy, if necessary.

In years past, the anatomy scan was referred to as the “Genetic survey” when the mother had risk factors for genetic problems. We now know that genetic or structural abnormalities can happen to any fetus, with or without risk factors in the mom. In Dr. Minior’s office, all women have the same type of late anatomic scan. Every fetus is examined for structural abnormalities as well as genetic “markers” that may be associated with an increased risk for a genetic abnormality. Every abnormality or marker that is detected is discussed with you so you can make informed decisions about how to proceed in your pregnancy. Often times, genetic “markers” are not very meaningful because you have already done several genetic screening tests that show that your fetus is most likely normal. Having an early anatomic survey in addition to a late anatomic survey, allows you to see if there are any problems early on as well as providing the most accurate assessment possible by re-evaluation at 20 weeks.

 

3D 4D Ultrasound Technology

The ultrasound equipment we use allows you to visualize what the fetus, or parts of the fetus look like in 3 dimensions. If an abnormality is detected in the fetus, it may be helpful for the doctor or the parents to understand what the defect looks like. It is also useful when looking for malformations of the uterus, such as a bicornuate or didelphic uterus. Most commonly, it is used to allow parents to see what their baby’s face will look like for the first time. 

 

Fetal Growth and Biophysical Profile (BPP)

A biophysical profile is performed after 24 weeks’ gestation. During this ultrasound test, different fetal behaviors are examined to make sure that the fetus is healthy and receiving plenty of oxygen. The fluid surrounding the fetus is evaluated. The weight of the fetus is estimated by measuring the head, abdomen and thigh bone. The weight is then calculated using a mathematical formula. The non-stress (NST) test is performed at your doctor’s request or if more information is necessary after performing the biophysical profile. During an NST the fetal heart rate is monitored for about 20 minutes while you relax in a reclining chair. Dr. Minior will talk to you after these tests and tell you how your baby is doing, and indicate if follow-up is required.

 

Doppler Evaluation

Fetal Doppler refers to an ultrasound test where blood flow is evaluated in a structure, most commonly the umbilical cord of the fetus. This test is an invaluable tool for determining how healthy the placenta is and how well it is functioning. Persistent Doppler abnormalities in the umbilical cord may predict when the fetus is not growing well or precede the development of pre-eclampsia. Sometimes Doppler abnormalities are detected when nothing else is wrong. In these cases, the Doppler is re-evaluated later just to make sure that all is well with the fetus.

Doppler is also used to evaluate a fetus when a low blood count (anemia) is suspected. In this case, a blood vessel in the fetal brain called the middle cerebral artery (MCA) is evaluated and the speed of flow in this vessel is compared to a reference range to determine if the fetus is likely to have a low blood count. 

This test is an invaluable tool for determining how healthy the placenta is and how well it is functioning.
 

Cervical Length Surveillance

Women who have had a previous preterm birth are sometimes at increased risk for this occurring again.  Monitoring cervical length can give more information on how likely that is to occur and Dr. Minior will suggest some treatment options if a short cervical length is detected.

 

Placental Location

Sometimes (about 20% of the time) the placenta is noted to be low in the uterus, near the cervix, at the 20-week anatomy scan.  In these cases, women are asked to return to the office at 28 weeks to re-evaluate the placental location.  About 95% of the time, the placenta “moves up” and out of the way as the baby and uterus grow. When the placenta is persistently low, this is called placenta previa. If the placenta is still low at 28 weeks, some precautions may be suggested and the patient is asked to return in 4-8 weeks for re-evaluation. If the placenta persists within 2 cm of the cervix near term, the fetus is delivered by cesarean section. If low placenta is seen in pregnancy, Dr. Minior will discuss this with you and review the plan going forward. 

 

Zika (or other virus) Screening

Sometimes when a woman is infected with the Zika virus during pregnancy, the virus can cause fetal brain and head abnormalities as well as impaired fetal growth. Signs of these conditions can be detected prenatally with careful surveillance of the fetal brain, head and body size.  Adverse effects due to other infectious diseases such as toxoplasmosis or cytomegalovirus can also be detected through ultrasound surveillance of the fetus. If a maternal infection with one of these conditions occurs before or during pregnancy, your doctor would refer you for surveillance of the fetus every few weeks throughout pregnancy.

 

Twin to Twin Transfusion Syndrome Screening

Women who are pregnant with identical twins (called monochorionic, diamiotic twins) are at risk for the development of twin-twin transfusion syndrome. In this type of twinning, the two fetuses share a single placenta. In rare cases, an imbalance can occur between how much blood is in one fetus vs. the other due to abnormal blood vessels in the placenta. This can be dangerous for the twins and can lead to neurologic injury or death. Fortunately, using ultrasound, signs of this condition can be detected using frequent surveillance of the pregnancy. Dr. Minior will look for an imbalance in the amniotic fluid between the twins, with one fetus becoming large and the other small. Doppler is used to look for anemia in the small twin and to evaluate blood flow to the placenta. If signs of the condition are detected, Dr. Minior will refer the patient for specialized treatment.

 

Additional Services & Specialties

DIABETES TREATMENT CENTER

Advanced expertise in education, management and treatment of diabetes in pregnancy including diabetic counseling & surveillance and Nutrition counseling

GYNECOLOGIC ULTRASOUND

From routine to complicated cases, we provide gynecologic ultrasound with careful attention to your personal comfort.  You will receive results from Dr. Minior on the day you are seen.

CENTER FOR TREATMENT OF DIABETES IN PREGNANCY

PRENATAL SCREENING & TESTING
MATERNAL-FETAL MEDICINE 

A full range of state-of-the-art prenatal screening and testing modalities that provide important information about factors that may affect your baby’s health.

A sub-specialty of obstetrics that focuses on the diagnosis and treatment of expectant mothers and their babies as well as care of pregnancies complicated by high risk conditions. 

Phone/Fax  646.453.4240

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Next Generation Women's Imaging and Maternal-Fetal Medicine   © Copyright 2019