8 weeks?

i had my first ultrasound today and my baby was measured at 8 weeks. i am just confused on measurement and age of fetus.i want to be accurate on date of conception since i dont really know the date of my last menstrual cycle but i know possible conception dates. does that mean i am really 8 weeks or does that mean 6 weeks since conception?

[Kevin Pho, MD]

The accuracy of ultrasound for dating a pregnancy depends on at what point during the pregnancy the ultrasound is taken. Pregnancy dating is most accurate during the first eighteen weeks of pregnancy. Measurement of the sac at five to seven weeks is not accurate. Measuring the crown-rump length gives an accuracy of plus or minus three days at seven weeks; this test can be used from the seventh to the fourteenth week. Between fourteen and twenty-six weeks, measurements of the biparietal diameter, the femur length and abdominal circumference are generally used. The accuracy is plus or minus seven to ten days. The accuracy further declines with advancing gestation age.

8 weeks suggests the age from conception.

Followup with your personal physician is essential.

This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.

Kevin, M.D.
kevinmd_b

[plexusnexus]

I am a health care provider in the South Central US.  Ultrasound reports that I receive give the gestational age of the baby.  So, here, we are given the age from the start of the last period. Conception tends to occur 2 weeks later (depending on the length of your cycle).  Also, from my experience whenever you are told that you are XX weeks along by professionals they are telling you dates from the last menstrual period.

Dr. Pho is accurate in his information.  But, you may just need to ask your doctor or midwife this question.  It may vary from hospital to hospital or office to office how ultrasound reports are reported.  And, in some situations, it can be very important to a patient when exactly conception occured.

[JAMY]

so 8 weeks transvaginal is + or - 7 to 10 days possibly from conception?

[JAMY]

is it 3 to five days of i dont understand