How Far Along Are You?
Obtain the most accurate dating of your pregnancy with an early pregnancy ultrasound
OMNI will accurately date your pregnancy (check your gestational age) and confirm your estimated date of delivery (EDD). Gestational age is usually considered to be the age of an embryo or foetus from the first day of the woman’s last menstrual period (LMP) to the current date. A transvaginal ultrasound in early pregnancy can accurately calculate how pregnant the woman is and in turn determine the EDD. During the early pregnancy scan, several measurements are taken including the crown rump length (CRL) and the fetal heart rate. The CRL is the distance from the top of baby’s head to the bottom of the spine. Based on this measurement, we can calculate the age of the pregnancy.
Determination of gestational age is important, because it provides valuable information for your Obstetrician regarding expected or potential problems and directly affects the medical treatment plan for the baby. In about 20% of all women who have an early pregnancy scan, prediction of the time of delivery is altered according to the ultrasound examination. Ultrasound is a better predictor of the time of delivery than the LMP.
The gestational age should not be confused with the fertilisation age of an embryo or fetus; the fertilisation age is always counted from fertilisation, and the gestational age is usually greater by about two weeks. The gestational age of children conceived by in vitro fertilisation (IVF) is known to the hour.
Are you having twins?
OMNI will confirm or exclude the presence of twins using high resolution ultrasound evaluation of the pregnancy. Multiple births include twins and higher order multiples (e.g. triplets, quadruplets). An early pregnancy scan can determine the number of fetuses (singleton or multiple) present.
The prevalence of multiple births has been increasing because of more widespread use of assisted reproductive technologies (ARTs) to treat infertility. The use of fertility drugs such as clompihene and other ARTS such as IVF or GIFT has contributed to the increasing number of higher order pregnancies.
Having diagnosed a twin pregnancy at the 1st trimester scan, it is important to determine if the fetuses have separate placentas or share the same placenta. This is referred to as the chorionicity and ultrasound gives us the answer. If the fetuses have separate placentas, then this is known as dichorionic (DC) twins. If however the babies share the same placenta, then this is known as monochorionic (MC) twins.
Why is it important to determine the number of placentas or chorionicity? Twin to Twin Transfusion Syndrome (TTTS) occurs in twins that share the same placenta (MC twins) and not in DC twins. TTTS is a condition in pregnancy that exists when blood passes disproportionately between twins with a shared placenta. This causes one twin to receive less than normal amounts of blood supply during pregnancy while the other receives too much. There are degrees to the severity of the syndrome, and it can be life-threatening due to the fact that it can worsen at any time during pregnancy. Therefore it is important to distinguish between MC and DC twins in the first trimester at an early ultrasound examination. The earlier the scan is performed in pregnancy, the easier this can be achieved. Once the chorionicity is known, then your Obstetrician can plan your pregnancy, frequency of interval scans and follow up accordingly.