EARLY PREGNANCY ULTRASOUND
What the ultrasound between 7 and 11 weeks can tell us
This scan is important for women who have had pain or bleeding in pregnancy, and useful for those with a history of ectopic pregnancy, those who are unsure of the date of their last period, those with a history of miscarriage, or those who simply want to be sure that the pregnancy is progressing normally.
The early pregnancy scan provides important information.
Whether the pregnancy is inside the uterine cavity (to exclude an ectopic pregnancy); whether it is a multiple pregnancy, and the chorionicity if it is
Assessment of the fetal heart activity and of the viability of the pregnancy.
Establishing or correcting the gestational age (in cases of irregular or abnormal cycles, anovulatory cycles and so on).
Very early diagnosis of major fetal anatomical abnormalities that bear directly on the viability of this pregnancy; and gynecological conditions (cysts, fibroids) that may affect the pregnancy
What can you expect to see at this early stage of your pregnancy?
5 weeks pregnant: a small gestational sac in the uterus, measuring about 3–4 millimetres.
6 weeks pregnant: inside the uterus a small gestational sac and perhaps the yolk sac (the future placenta). By about 7 weeks, the fetal pole — as the embryo is called at this stage — which measures only a few millimetres (the size of a grain of rice); with a fetal heartbeat present, the chance of a successful pregnancy is 78%.
7 weeks pregnant: the embryo usually measures 10–20 mm, with cardiac activity present.
8 weeks pregnant: the embryo now measures 20–30 mm. The chance of a successful pregnancy is 98%.
10 weeks pregnant: the embryo now measures 35–40 millimetres and, if cardiac activity is present and the measurements match the gestational age, the chance of a successful pregnancy is 99.4%.
11 weeks pregnant and beyond: the fetus now measures about 45 millimetres and clearly has a distinct head, body, arms and legs. We can see the heart beating in the chest, the stomach and the bladder. From this point on the baby simply has to grow.
The procedure — the scan is done transabdominally or transvaginally and is, in either case, completely safe. The transvaginal approach is superior at this early stage, however, since it gives a clearer image thanks to the short distance between the probe and the uterus. The examination takes about 15 minutes.