U.S. doctors online nowAsk doctors free
A 33-year-old female asked:

If ultrasounds have margin of error, how do u know when you're within the range of when the nt scan should be done?does fetus have to be certain size?

1 doctor answer2 doctors weighed in
Dr. Jane Van Dis
Obstetrics and Gynecology 20 years experience
Best estimate : The margin of error for ultrasound dating is the smallest in the first trimester, which is when the nuchal translucency scans are performed. Yes the fetus does have to be a certain size and between certain dates in order for the information to be accurate.
Created for people with ongoing healthcare needs but benefits everyone.
Last updated Jan 6, 2015


Content on HealthTap (including answers) should not be used for medical advice, diagnosis, or treatment, and interactions on HealthTap do not create a doctor-patient relationship. Never disregard or delay professional medical advice in person because of anything on HealthTap. Call your doctor or 911 if you think you may have a medical emergency.