5 doctors weighed in:

U/s tech said i was 17wks&4 days based on lmp, but then said i was 18 weeks once she started the ultrasound. Why did that change? What did she go by?

5 doctors weighed in
Dr. Nikolaos Zacharias
Obstetrics & Gynecology - Maternal Fetal Medicine
1 doctor agrees

In brief: No change.

Prenatal ultrasound is not that accurate at 18 weeks(+/-7-10 days).
Your menstrual dates should be used if the difference is within that range of confidence.

In brief: No change.

Prenatal ultrasound is not that accurate at 18 weeks(+/-7-10 days).
Your menstrual dates should be used if the difference is within that range of confidence.
Dr. Nikolaos Zacharias
Dr. Nikolaos Zacharias
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Dr. Andrew Doe
Radiology - Interventional

In brief: See my other answer

It is hard to tell.
There are numerous measurements involved. (head circumference, abdominal circumference, femur length, humeral length, biparietal diameter, etc etc....).

In brief: See my other answer

It is hard to tell.
There are numerous measurements involved. (head circumference, abdominal circumference, femur length, humeral length, biparietal diameter, etc etc....).
Dr. Andrew Doe
Dr. Andrew Doe
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Dr. Pouya Shafipour
Family Medicine

In brief: Measurement

When she measured your baby the age of the baby most likely changed since the ultrasound measurement was larger than your date based on lmp.
This is normal.

In brief: Measurement

When she measured your baby the age of the baby most likely changed since the ultrasound measurement was larger than your date based on lmp.
This is normal.
Dr. Pouya Shafipour
Dr. Pouya Shafipour
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Dr. Joseph Mele
Surgery - Plastics

In brief: Educated guess

It is not unusual to get two different answers when using two different methods to determine gestation.
Neither is exact, they are guesses based on history and what your technologist is seeing. Please discuss this with your ob/gyn as they have more information with which to make the determination. Due dates often change, and in the end, it's mostly the baby that determines when it is time.

In brief: Educated guess

It is not unusual to get two different answers when using two different methods to determine gestation.
Neither is exact, they are guesses based on history and what your technologist is seeing. Please discuss this with your ob/gyn as they have more information with which to make the determination. Due dates often change, and in the end, it's mostly the baby that determines when it is time.
Dr. Joseph Mele
Dr. Joseph Mele
Thank
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