QuestionHi I have a couple of questions regarding a pregnancy ultrasound.
1. I have an ultrasound which is giving me 2 different time frames for the same ultrasound. GA 6w 4d and 7w 6d. which one would i consider as to where the pregnancy is at.
2. There is also a reading of GS 28.8mm +/- 10.5mm could you please explain these to me.
3. When does the baby show a heart rate. On one of the ultrasounds it is showing FHR 141 bpm 2."
AnswerSee the two dates you mentioned must have been from two different readings. In USG dates are estimated by taking measurements of key structures. At your stage of pregnancy the commonest measurement taken include the crown rump length which is useful till 13 weeks. Therefore it is entirely possible for you to have an USG which mentions two dates as these are based on measurement of two different structures. I know that this is difficult to understand, but this is because of the sampling errors sampling. To know which date you should consider as accurate look at your report and take the date measure by crown rump length. This is more accurate. In USG it is denoted as CRL.
The word GS means the size of the gestational sac. Since the sac is a fluid filled body the actual size is quite difficult to estimate by USG. Therefore a range is given. So when it says GS 28mm +/- 10.5 mm, it means that the gestational sac is between 17.5 to 38.5 mm in size. Although this is a huge variation, the gestational sac is actually around 28 mm or so, but once again these formula are used to correct for the sampling errors.
The baby's heart can be seen from six weeks and a HR f 141 is normal.
