What is an OB Ultrasound?

An obstetric ultrasound also called an OB ultrasound, is a medical test that produces pictures of a pregnant woman’s baby, uterus, and ovaries. This procedure is usually performed for all pregnant women at 20 weeks gestation to check that your baby is growing properly in your uterus. It is also performed for many other reasons, including checking the baby’s position in the womb, identifying the number of babies in the womb, first-trimester screening for chromosomal abnormalities, determining the gender of the baby, and more. This procedure is completely painless and non-surgical and is an important part of monitoring your pregnancy.

“I highly recommend Dr. Tepper!He is highly professional, experienced, and calming. My pregnancy and birth were such a positive experience thanks to him and his lovely staff at the clinic.”


The OB Ultrasound Procedure

Before your ultrasound appointment, you may be asked to drink 4-6 glasses of water to fill up your bladder. This helps Dr. Tepper to see the baby better on the ultrasound. During your test, you will lie down on a comfortable exam table, and a water-soluble gel will be applied to your abdomen. A device called a transducer will then be used to send high-frequency sound waves into your body, which will bounce off internal structures, including your baby. These sound waves will then be received by the transducer and changed into pictures for you and your doctor to view.

In most instances, the ultrasound will be performed on the surface of the skin, though a transvaginal ultrasound may be required in some cases. In these instances, a probe will be inserted into the vaginal canal to produce more detailed images of the uterus and ovaries. This option may be used early on in pregnancy to determine how far along you are in your pregnancy or to diagnose a suspected problem.

Once the OB ultrasound is completed, the gel will be removed from your skin and you will be able to use the restroom. The test generally takes about 30 minutes to complete.


Welcome to my practice. Let me introduce myself and my practice philosophy. I am a board certified OB/GYN in practice for over 20 years and have been a solo-practitioner on the Upper East Side of Manhattan since 2000. All deliveries are performed at The Mount Sinai Medical Center where I went to medical school and at Lenox Hill Hospital.

When Should I Get an OB Ultrasound?

If you are pregnant and are not sure when you should receive an OB ultrasound, be sure to speak with your OBGYN. In general, women usually undergo ultrasounds following this schedule:

  • Early pregnancy: The first ultrasound of your pregnancy may be performed around 6-8 weeks. During this ultrasound, your doctor will listen for your baby’s heartbeat, will determine a more accurate due date, tell you if you are pregnant with multiples, and will determine if an ectopic pregnancy is present.
  • Dating ultrasound: If you did not receive an early pregnancy ultrasound, this may be your first ultrasound appointment, which is around 10-13 weeks of pregnancy. During this test, Dr. Tepper can predict your due date, reveal the number of babies in the womb, check for your baby’s heartbeat, and examine the baby’s basic anatomy.
  • Anatomical survey: This OB ultrasound is performed between 18-20 weeks. During this test, your doctor will examine the anatomy of your baby, take measurements of the baby, and look for physical characteristics that may indicate any abnormalities.


Whether you are a new or returning patient, Dr. Tepper can assess your concerns and discuss your options to find the most comfortable and convenient care for you. To get started, call our office to set up an appointment.


Contact Us to Learn More

For more information about what to expect during your OB ultrasound, or to schedule an appointment with Dr. Tepper, contact our New York office today at (212) 828-0900.

Frequently Asked Questions

Can birth defects be seen on ultrasound?

Many birth defects and obstetrical issues can be detected with ultrasounds. The anatomical and level 2 sonograms are performed by our maternal fetal medicine associates. If issues arise, follow up scans, consults and monitoring are performed with our maternal fetal medicine team to insure a successful outcome for both mom and baby.

Can having too many ultrasounds hurt the baby?

Modern sonography does not hurt the baby and is actually a vital tool in maximizing fetal well being.

Do obstetricians do ultrasounds?

yes and certain scans are performed by the maternal fetal medicine specialists

How do I prepare for an ultrasound?

a full bladder always makes the scan easier to perform.

How early can fetal abnormalities be detected?

complicated question but certain issues can be detected as early as 4 wks from conception

How long does a prenatal ultrasound take?

routine growth scans and viability checks can be as quick as 10 minutes while a full anatomical survey can take much longer

Is an ultrasound considered routine prenatal care?

We consider a sonogram an essential component of quality prenatal care and employ a sonogram at every visit

Is an ultrasound the same as a sonogram?

Yes but there are different types of scans performed depending on the gestational age and clinical scenario.

What abnormalities can be detected on an ultrasound?

Twin gestations and incorrect dating are two of the more common benign issues that can be detected via ultrasound. More complicated issues such placenta previa , fetal growth restriction, macrosomia and structural anomalies are some of the more complex issues that can be detected with sonograms.

What are signs of abnormal pregnancy?

While bleeding can often be due to a benign reason, it is always a reason to contact your physician .

What is the purpose of prenatal ultrasound?

To maximize the opportunity for a positive outcome

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