Such measurements form the cornerstone in the assessment of gestational age, size and growth in the fetus.
For example, if ultrasound scan demonstrates a 7mm embryo but cannot demonstrable a clearcut heartbeat, a missed abortion may be diagnosed.
In such cases, it is reasonable to repeat the ultrasound scan in 7-10 days to avoid any error.
Normal heart rate at 6 weeks is around 90-110 beats per minute (bpm) and at 9 weeks is 140-170 bpm.
At 5-8 weeks a bradycardia (less than 90 bpm) is associated with a high risk of miscarriage.
Ultrasound can also very importantly confirm the site of the pregnancy is within the cavity of the uterus. A visible heartbeat could be seen and detectable by pulsed doppler ultrasound by about 6 weeks and is usually clearly depictable by 7 weeks.
If this is observed, the probability of a continued pregnancy is better than 95 percent.
There may be some discomfort from pressure on the full bladder.
The conducting gel is non-staining but may feel slightly cold and wet.
Ultrasound scan is currently considered to be a safe, non-invasive, accurate and cost-effective investigation in the fetus. The gestational sac can be visualized as early as four and a half weeks of gestation and the yolk sac at about five weeks.
It has progressively become an indispensible obstetric tool and plays an important role in the care of every pregnant woman. The embryo can be observed and measured by about five and a half weeks. The viability of the fetus can be documented in the presence of vaginal bleeding in early pregnancy.
Many women do not ovulate at around day 14, so findings after a single scan should always be interpreted with caution.