Early Pregnancy Scan

The early pregnancy scans are performed before 12 weeks gestation.

Reasons for scan:

·         Dating (irregular menstrual cycle or unknown last period)
·         History of previous miscarriage
·         History of ectopic pregnancy
·         Bleeding/ pain in early pregnancy
·         Excessive nausea (hyperemesis)
·         Suboptimal or excessive BHCG (pregnancy hormone) levels

Early Ultrasound benefits:

·         Confirm viable pregnancy and location (heartbeat seen from approximately 6 weeks)
·         May exclude ectopic pregnancy
·         Assess dates
·         Presence of ovarian cysts or uterine fibroid

How scan is performed:

At 8 weeks of pregnancy an embryo can often be seen well by assessing the lower abdomen with a full bladder (transabdominal scan).
Earlier than 8 weeks or if not well visualised an internal (transvaginal) scan may be performed to achieve optimal visualisation.

Timing of scan:

The timing of TVS scan will depend on the reason it is being performed. Patients with pain or bleeding will be seen urgently. If reassurance is required 7 to 8 weeks is ideal as more information can be obtained from the scan.

Ultrasound Visualisation:

·         5 weeks – pregnancy sac
·         6 weeks – embryo
·         Fetal heart, usually visualised when embryo 4 mm

Dating accuracy:

Dating is most accurately performed between 7 and 11 weeks. Measurement of the embryo (crown-rump length) is accurate to 3 days.