Pregnancy ultrasound

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Pregnancy ultrasound
Pregnancy ultrasound

An ultrasound exam is a procedure that uses sound waves to scan a woman’s abdomen creating a picture (sonogram) of the baby and placenta

Are ultrasounds safe? There’s no evidence that scans are harmful, if used according to clinical guidelines. Ultrasound scans have been used in pregnancy for decades. The person carrying out the scans (Radiologist) will follow clinical guidelines to ensure that you and your baby are safe.

How can I be sure it's performed safely? Medical professionals do this by using low levels of ultrasound wherever possible, and performing each scan as quickly as possible. Doctors know that:




  • Doppler, particularly with a vaginal probe, should not be used in the early weeks, when your baby is still developing.
  • Bone heats up much more quickly than soft tissue. Your baby’s bones start to form at about 12 weeks. In late pregnancy your baby's skull is a particularly sensitive area.
  • The probe should not be held still for a long time.
  • The scan should be very brief if you have a fever, as you'll already have a raised temperature. Most experts agree that it's extremely unlikely that scans can cause any harm, if used according to clinical guidelines.

What types of ultrasound are there? There are basically seven different ultrasound exams, but the principle process is the same.

The different types of procedures include:

  • Transvaginal Scans: Specially designed probe transducers are used inside the vagina to generate sonogram images. Most often used during early pregnancy.
  • Standard Ultrasound: Traditional ultrasound exam which uses a transducer over the abdomen to generate 2-D images of the developing foetus.
  • Doppler Ultrasound: This imaging procedure measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells.
  • 3-D Ultrasound: Uses specially designed probes and software to generate 3-D images of the developing foetus.
  • 4-D or Dynamic 3-D Ultrasound: Uses specially designed scanners to look at the face and movements of the baby prior to delivery.
  • Foetal Echocardiography: Uses ultrasound waves to assess the baby’s heart anatomy and function. This is used to help assess suspected congenital heart defects.

How is an ultrasound performed? The traditional ultrasound procedure involves placing gel on your abdomen to work as a conductor for the sound waves.

When are ultrasounds performed? Ultrasounds may be performed at any point during pregnancy, there is not a recommended number of ultrasounds that should be performed. Additional ultrasounds might be ordered separately if your healthcare provider suspects a complication or problem related to your pregnancy.

What does the ultrasound look for? Ultrasounds are diagnostic procedures that detect or aid in the detection of abnormalities and conditions related to pregnancy. An ultrasound exam is medically indicated throughout pregnancy for the following reasons:

First Trimester:

  • Confirm viable pregnancy
  • Confirm heartbeat
  • Measure the gestational age
  • Assess abnormal gestation

Second Trimester:

  • Diagnose foetal malformation
  • Weeks 12-14 for characteristics of potential Down syndrome
  • Weeks 18-22 for congenital malformations
  • Structural abnormalities
  • Confirm multiples pregnancy
  • Verify dates and growth
  • Measure excessive or reduced levels of amniotic fluid (liquid around the foetus)
  • Evaluation of foetal well-being

 Third Trimester:

  • Identify placental location
  • Observe foetal presentation
  • Observe foetal movements
  • Identify uterine and pelvic abnormalities of the mother.

When can an ultrasound determine the sex of the baby? You may have an ultrasound between 18 to 22 weeks to evaluate the baby. It may also be possible to determine the gender of your baby during this ultrasound. Several factors, such as the stage of pregnancy and position of foetus, will influence the accuracy of the gender prediction.

Are ultrasounds a necessary part of prenatal care? Ultrasounds enable your healthcare provider to evaluate the baby’s well-being as well as diagnose potential problems.


Dr. Heba Osama El Sayed Ali Specialist Radiology