Dating ultrasound too early
5 ½ weeks gestation means 5 ½ weeks from the first day of the last menstrual period, which is usually about 3 ½ weeks from the date of conception (confusing, isn’t it!) the fetus is clearly seen on trans-vaginal ultrasound and the heart beat can be seen at this early stage (90 to 110 beats per minute under 6 to 7 weeks, then 110 to 200 beats per minute as the baby matures).For these reasons, each woman is likely to see or hear her baby’s heartbeat at different stages in her pregnancy. Some women will have early ultrasounds to confirm pregnancy, or to check the location of the pregnancy if there’s any concern (e.g. Some scans can detect a gestational sac around 4-5 weeks of pregnancy, but that’s still too early to detect a heartbeat.Your pregnancy is dated from the first day of your last menstrual cycle.Early Pregnancy Scans are not routinely offered on the NHS but you may have one privately without affecting your NHS entitlement.
One question many mothers have is when can they see their baby’s heartbeat on ultrasound.Early Pregnancy Scans are normally performed trans-abdominally (through your tummy) however an internal (vaginal) scan may be required at earlier gestations ie 6-7 weeks to see all the necessary detail, or if your womb tilts backwards (retroverted).We will always try to scan trans-abdominally first but if we need to do an internal scan then this will not be harmful in any way to the baby and would be discussed prior to having the scan.This is the period of time which provides the most accurate assessment.Generally, ultrasounds which are performed in the first trimester are within 3-5 days of being accurate in terms of assessing gestational age.
At around seven weeks of pregnancy, it’s reasonably common for women to have their first ultrasound.