How ultrasound works:

A high pitched sound is transmitted through a probe. When this sound wave enters the body, it reflects the sound back from any structure it encounters. The ultrasound machine recognizes the sound reflection and creates images based on what type of structure it is hitting. Liquid is reflected as black; bone is reflected as white; and most other tissues are various shades of grey.

Purpose of an Ultrasound:

• Early pregnancy scan: 
  – Fetal measurements are taken to estimate gestational age (until about 13-14 weeks for accuracy)
  – Fetal placement is checked to verify that the fetus is inside the uterus
  – Twins and multiples can be examined
  –  Severe abnormalities can be detected
  – One marker of Down syndrome can be screened for
  – Any suspicious bleeding, pain, or other problem can be examined
  
  
• 18-22 week fetal anatomy screening:
  – Head-to-toe scan of fetal parts are examined for any abnormalities. (About 50% of significant abnormalities can be identified at this time)
  – Gender is identifiable if the parents choose to receive this information
  – Twins and multiple gestation can be examined
  
  
• Late pregnancy scan (usually done for a specific reason):
  – Fetal well-being: if there are questionable fetal heart rate patterns or other concerns
  – Fetal growth: if the fetus is having questionable growth patterns
  – Placental function: If the pregnancy is going longer than expected, then using ultrasound to check the placenta’s functioning and fetal-well being may be suggested as a part of care.
  – To verify fetal position if unsure

Potential benefits of ultrasound:

• Early ultrasounds can accurately date the fetus when the gestational age is unknown
• Bleeding, pain, or other unusual problems can be identified
• Some fetal anomalies can be identified and appropriate care can be provided
• Problems during pregnancy can be monitored more closely; for example, IUGR
• In some cases, maternal reassurance of fetal well-being is a benefit
• Visual opportunity to bond with unborn baby

Potential risks of ultrasound:

• There is little research on the effects of ultrasound, but frequent obstetrical use shows low or not an obvious risk.
• Slight tissue heating within the first 40 seconds of exposure
• Possible association with low birth weight
• Possible association with dyslexia
• Possible associate with non right-handedness
• Missed fetal anomaly that may have changed the course of care
• Misdiagnosed fetal anomalies
• Anxiety and stress that may not be necessary; possibly due to finding an anomaly that doesn’t affect the fetus.

Testing associated with ultrasound:

• Early gestational age assessment
• 18-20 fetal anomaly screen
• Bio-physical profile
• Amniotic fluid estimation
  
  
  
  
  
  

***This is general information. Please speak to your health care provider about your unique health needs.