Dating ultrasound measurements
3-D Ultrasound – Uses specially designed probes and software to generate 3-D images of the developing fetus.
Fetal growth assessment, either clinically or by ultrasound evaluation, also relies on accurate assessment of gestational age.Gestational age, synonymous with menstrual age, is defined in weeks beginning from the first day of the last menstrual period (LMP) prior to conception.Accurate determination of gestational age is fundamental to obstetric care and is important in a variety of situations.An ultrasound exam is a procedure that uses high-frequency sound waves to scan a woman’s abdomen and pelvic cavity, creating a picture (sonogram) of the baby and placenta.Although the terms ultrasound and sonogram are technically different, they are used interchangeably and reference the same exam.Crown/rump length and gestational age are closely compared with each other until around the end of the first trimester.
The ideal time for a sonographer to assess the gestational age in the first trimester is between 7-10 weeks of pregnancy.
At around seven weeks of pregnancy, it’s reasonably common for women to have their first ultrasound.
This can be for many reasons but the most common is to confirm pregnancy and to check that the embryo is viable and “everything’s ok”.
You may need to have a full bladder for this scan, as this makes the ultrasound image clearer.
You can ask your midwife or doctor before the scan if this is the case. Find out more about what happens during a pregnancy ultrasound scan.
Similarly, the magnitude of increased optical density above baseline at 450 nm (delta OD 450) by amniotic fluid spectrophotometric measurement is used to predict the severity of fetal hemolytic disease in pregnancies complicated by rhesus isoimmunization.